diff --git a/server/.pylintrc b/server/.pylintrc
new file mode 100644
index 00000000..e8f00489
--- /dev/null
+++ b/server/.pylintrc
@@ -0,0 +1,14 @@
+[basic]
+method-rgx=[a-z_][a-z0-9_]{2,30}$|^test_
+
+[variables]
+dummy-variables-rgx=_|dummy
+
+[format]
+max-line-length=90
+
+[messages control]
+disable=missing-docstring,no-self-use,too-few-public-methods
+
+[typecheck]
+generated-members=add|add_all
diff --git a/server/szurubooru/api/base_api.py b/server/szurubooru/api/base_api.py
index f8249a6c..6170d47c 100644
--- a/server/szurubooru/api/base_api.py
+++ b/server/szurubooru/api/base_api.py
@@ -1,12 +1,10 @@
-''' Exports BaseApi. '''
-
 import types
 
 def _bind_method(target, desired_method_name):
     actual_method = getattr(target, desired_method_name)
-    def _wrapper_method(self, request, response, *args, **kwargs):
+    def _wrapper_method(_self, request, _response, *args, **kwargs):
         request.context.result = actual_method(
-            request, request.context, *args, **kwargs)
+            request.context, *args, **kwargs)
     return types.MethodType(_wrapper_method, target)
 
 class BaseApi(object):
diff --git a/server/szurubooru/api/password_reminder_api.py b/server/szurubooru/api/password_reminder_api.py
index 2fc012a6..659355aa 100644
--- a/server/szurubooru/api/password_reminder_api.py
+++ b/server/szurubooru/api/password_reminder_api.py
@@ -1,47 +1,47 @@
-''' Exports PasswordReminderApi. '''
-
 import hashlib
+from szurubooru import errors
 from szurubooru.api.base_api import BaseApi
-from szurubooru.errors import ValidationError, NotFoundError
+
+MAIL_SUBJECT = 'Password reset for {name}'
+MAIL_BODY = \
+    'You (or someone else) requested to reset your password on {name}.\n' \
+    'If you wish to proceed, click this link: {url}\n' \
+    'Otherwise, please ignore this email.'
 
 class PasswordReminderApi(BaseApi):
-    ''' API for password reminders. '''
     def __init__(self, config, mailer, user_service):
         super().__init__()
         self._config = config
         self._mailer = mailer
         self._user_service = user_service
 
-    def get(self, request, context, user_name):
+    def get(self, context, user_name):
         user = self._user_service.get_by_name(context.session, user_name)
         if not user:
-            raise NotFoundError('User %r not found.' % user_name)
+            raise errors.NotFoundError('User %r not found.' % user_name)
         if not user.email:
-            raise ValidationError(
+            raise errors.ValidationError(
                 'User %r hasn\'t supplied email. Cannot reset password.' % user_name)
         token = self._generate_authentication_token(user)
+        url = '%s/password-reset/%s' % (
+            self._config['basic']['base_url'].rstrip('/'), token)
         self._mailer.send(
             'noreply@%s' % self._config['basic']['name'],
             user.email,
-            'Password reset for %s' % self._config['basic']['name'],
-            'You (or someone else) requested to reset your password on %s.\n'
-            'If you wish to proceed, click this link: %s/password-reset/%s\n'
-            'Otherwise, please ignore this email.' %
-                (self._config['basic']['name'],
-                self._config['basic']['base_url'].rstrip('/'),
-                token))
+            MAIL_SUBJECT.format(name=self._config['basic']['name']),
+            MAIL_BODY.format(name=self._config['basic']['name'], url=url))
         return {}
 
-    def post(self, request, context, user_name):
+    def post(self, context, user_name):
         user = self._user_service.get_by_name(context.session, user_name)
         if not user:
-            raise NotFoundError('User %r not found.' % user_name)
+            raise errors.NotFoundError('User %r not found.' % user_name)
         good_token = self._generate_authentication_token(user)
         if not 'token' in context.request:
-            raise ValidationError('Missing password reset token.')
+            raise errors.ValidationError('Missing password reset token.')
         token = context.request['token']
         if token != good_token:
-            raise ValidationError('Invalid password reset token.')
+            raise errors.ValidationError('Invalid password reset token.')
         new_password = self._user_service.reset_password(user)
         context.session.commit()
         return {'password': new_password}
diff --git a/server/szurubooru/api/user_api.py b/server/szurubooru/api/user_api.py
index e4134c63..946c4133 100644
--- a/server/szurubooru/api/user_api.py
+++ b/server/szurubooru/api/user_api.py
@@ -1,11 +1,9 @@
-''' Exports UserListApi and UserDetailApi. '''
-
 import re
 import sqlalchemy
+from szurubooru import errors
+from szurubooru import util
 from szurubooru.api.base_api import BaseApi
-from szurubooru.errors import IntegrityError, ValidationError, NotFoundError, AuthError
-from szurubooru.services.search import UserSearchConfig, SearchExecutor
-from szurubooru.util import is_valid_email
+from szurubooru.services import search
 
 def _serialize_user(authenticated_user, user):
     ret = {
@@ -22,17 +20,18 @@ def _serialize_user(authenticated_user, user):
 
 class UserListApi(BaseApi):
     ''' API for lists of users. '''
+
     def __init__(self, auth_service, user_service):
         super().__init__()
         self._auth_service = auth_service
         self._user_service = user_service
-        self._search_executor = SearchExecutor(UserSearchConfig())
+        self._search_executor = search.SearchExecutor(search.UserSearchConfig())
 
-    def get(self, request, context):
+    def get(self, context):
         ''' Retrieves a list of users. '''
         self._auth_service.verify_privilege(context.user, 'users:list')
-        query = request.get_param_as_string('query')
-        page = request.get_param_as_int('page', 1)
+        query = context.get_param_as_string('query')
+        page = context.get_param_as_int('page', 1)
         count, users = self._search_executor.execute(context.session, query, page)
         return {
             'query': query,
@@ -42,7 +41,7 @@ class UserListApi(BaseApi):
             'users': [_serialize_user(context.user, user) for user in users],
         }
 
-    def post(self, request, context):
+    def post(self, context):
         ''' Creates a new user. '''
         self._auth_service.verify_privilege(context.user, 'users:create')
 
@@ -51,18 +50,19 @@ class UserListApi(BaseApi):
             password = context.request['password']
             email = context.request['email'].strip()
         except KeyError as ex:
-            raise ValidationError('Field %r not found.' % ex.args[0])
+            raise errors.ValidationError('Field %r not found.' % ex.args[0])
 
         user = self._user_service.create_user(
             context.session, name, password, email)
         try:
             context.session.commit()
         except sqlalchemy.exc.IntegrityError:
-            raise IntegrityError('User %r already exists.' % name)
+            raise errors.IntegrityError('User %r already exists.' % name)
         return {'user': _serialize_user(context.user, user)}
 
 class UserDetailApi(BaseApi):
     ''' API for individual users. '''
+
     def __init__(self, config, auth_service, password_service, user_service):
         super().__init__()
         self._available_access_ranks = config['service']['user_ranks']
@@ -72,19 +72,19 @@ class UserDetailApi(BaseApi):
         self._auth_service = auth_service
         self._user_service = user_service
 
-    def get(self, request, context, user_name):
+    def get(self, context, user_name):
         ''' Retrieves an user. '''
         self._auth_service.verify_privilege(context.user, 'users:view')
         user = self._user_service.get_by_name(context.session, user_name)
         if not user:
-            raise NotFoundError('User %r not found.' % user_name)
+            raise errors.NotFoundError('User %r not found.' % user_name)
         return {'user': _serialize_user(context.user, user)}
 
-    def put(self, request, context, user_name):
+    def put(self, context, user_name):
         ''' Updates an existing user. '''
         user = self._user_service.get_by_name(context.session, user_name)
         if not user:
-            raise NotFoundError('User %r not found.' % user_name)
+            raise errors.NotFoundError('User %r not found.' % user_name)
 
         if context.user.user_id == user.user_id:
             infix = 'self'
@@ -96,7 +96,7 @@ class UserDetailApi(BaseApi):
                 context.user, 'users:edit:%s:name' % infix)
             name = context.request['name'].strip()
             if not re.match(self._name_regex, name):
-                raise ValidationError(
+                raise errors.ValidationError(
                     'Name must satisfy regex %r.' % self._name_regex)
             user.name = name
 
@@ -105,7 +105,7 @@ class UserDetailApi(BaseApi):
             self._auth_service.verify_privilege(
                 context.user, 'users:edit:%s:pass' % infix)
             if not re.match(self._password_regex, password):
-                raise ValidationError(
+                raise errors.ValidationError(
                     'Password must satisfy regex %r.' % self._password_regex)
             user.password_salt = self._password_service.create_password()
             user.password_hash = self._password_service.get_password_hash(
@@ -114,12 +114,10 @@ class UserDetailApi(BaseApi):
         if 'email' in context.request:
             self._auth_service.verify_privilege(
                 context.user, 'users:edit:%s:email' % infix)
-            email = context.request['email'].strip()
-            if not is_valid_email(email):
-                raise ValidationError('%r is not a vaild email address.' % email)
-            # prefer nulls to empty strings in the DB
-            if not email:
-                email = None
+            email = context.request['email'].strip() or None
+            if not util.is_valid_email(email):
+                raise errors.ValidationError(
+                    '%r is not a vaild email address.' % email)
             user.email = email
 
         if 'accessRank' in context.request:
@@ -127,12 +125,12 @@ class UserDetailApi(BaseApi):
                 context.user, 'users:edit:%s:rank' % infix)
             rank = context.request['accessRank'].strip()
             if not rank in self._available_access_ranks:
-                raise ValidationError(
+                raise errors.ValidationError(
                     'Bad access rank. Valid access ranks: %r' \
                         % self._available_access_ranks)
             if self._available_access_ranks.index(context.user.access_rank) \
                     < self._available_access_ranks.index(rank):
-                raise AuthError(
+                raise errors.AuthError(
                     'Trying to set higher access rank than one has')
             user.access_rank = rank
 
@@ -141,6 +139,6 @@ class UserDetailApi(BaseApi):
         try:
             context.session.commit()
         except sqlalchemy.exc.IntegrityError:
-            raise IntegrityError('User %r already exists.' % name)
+            raise errors.IntegrityError('User %r already exists.' % name)
 
         return {'user': _serialize_user(context.user, user)}
diff --git a/server/szurubooru/app.py b/server/szurubooru/app.py
index 08739e54..e23cdb50 100644
--- a/server/szurubooru/app.py
+++ b/server/szurubooru/app.py
@@ -1,16 +1,15 @@
 ''' Exports create_app. '''
 
-import os
 import falcon
 import sqlalchemy
 import sqlalchemy.orm
 import szurubooru.api
 import szurubooru.config
+import szurubooru.errors
 import szurubooru.middleware
 import szurubooru.services
 import szurubooru.services.search
 import szurubooru.util
-from szurubooru.errors import *
 
 class _CustomRequest(falcon.Request):
     context_type = szurubooru.util.dotdict
@@ -28,28 +27,26 @@ class _CustomRequest(falcon.Request):
             return default
         raise falcon.HTTPMissingParam(name)
 
-def _on_auth_error(ex, request, response, params):
+def _on_auth_error(ex, _request, _response, _params):
     raise falcon.HTTPForbidden(
         title='Authentication error', description=str(ex))
 
-def _on_validation_error(ex, request, response, params):
+def _on_validation_error(ex, _request, _response, _params):
     raise falcon.HTTPBadRequest(title='Validation error', description=str(ex))
 
-def _on_search_error(ex, request, response, params):
+def _on_search_error(ex, _request, _response, _params):
     raise falcon.HTTPBadRequest(title='Search error', description=str(ex))
 
-def _on_integrity_error(ex, request, response, params):
+def _on_integrity_error(ex, _request, _response, _params):
     raise falcon.HTTPConflict(
         title='Integrity violation', description=ex.args[0])
 
-def _on_not_found_error(ex, request, response, params):
+def _on_not_found_error(ex, _request, _response, _params):
     raise falcon.HTTPNotFound(title='Not found', description=str(ex))
 
 def create_app():
     ''' Creates a WSGI compatible App object. '''
     config = szurubooru.config.Config()
-    root_dir = os.path.dirname(__file__)
-    static_dir = os.path.join(root_dir, os.pardir, 'static')
 
     engine = sqlalchemy.create_engine(
         '{schema}://{user}:{password}@{host}:{port}/{name}'.format(
@@ -77,9 +74,10 @@ def create_app():
     app = falcon.API(
         request_type=_CustomRequest,
         middleware=[
+            szurubooru.middleware.ImbueContext(),
             szurubooru.middleware.RequireJson(),
             szurubooru.middleware.JsonTranslator(),
-            szurubooru.middleware.DbSession(session_maker),
+            szurubooru.middleware.DbSession(scoped_session),
             szurubooru.middleware.Authenticator(auth_service, user_service),
         ])
 
diff --git a/server/szurubooru/config.py b/server/szurubooru/config.py
index 3681ddbf..d5bb065e 100644
--- a/server/szurubooru/config.py
+++ b/server/szurubooru/config.py
@@ -1,11 +1,6 @@
-''' Exports Config. '''
-
 import os
 import configobj
-
-class ConfigurationError(RuntimeError):
-    ''' A problem with config.ini file. '''
-    pass
+import szurubooru.errors
 
 class Config(object):
     ''' INI config parser and container. '''
@@ -26,13 +21,14 @@ class Config(object):
         all_ranks = self['service']['user_ranks']
         for privilege, rank in self['privileges'].items():
             if rank not in all_ranks:
-                raise ConfigurationError(
+                raise szurubooru.errors.ConfigError(
                     'Rank %r for privilege %r is missing from user_ranks' % (
                         rank, privilege))
         for rank in ['anonymous', 'admin', 'nobody']:
             if rank not in all_ranks:
-                raise ConfigurationError('Fixed rank %r is missing from user_ranks' % rank)
+                raise szurubooru.errors.ConfigError(
+                    'Fixed rank %r is missing from user_ranks' % rank)
         if self['service']['default_user_rank'] not in all_ranks:
-            raise ConfigurationError(
+            raise szurubooru.errors.ConfigError(
                 'Default rank %r is missing from user_ranks' % (
                     self['service']['default_user_rank']))
diff --git a/server/szurubooru/errors.py b/server/szurubooru/errors.py
index fa42ab25..90b8c656 100644
--- a/server/szurubooru/errors.py
+++ b/server/szurubooru/errors.py
@@ -1,4 +1,5 @@
-''' Exports custom errors. '''
+class ConfigError(RuntimeError):
+    ''' A problem with config.ini file. '''
 
 class AuthError(RuntimeError):
     ''' Generic authentication error '''
diff --git a/server/szurubooru/middleware/__init__.py b/server/szurubooru/middleware/__init__.py
index a2ba328d..e958790f 100644
--- a/server/szurubooru/middleware/__init__.py
+++ b/server/szurubooru/middleware/__init__.py
@@ -4,3 +4,4 @@ from szurubooru.middleware.authenticator import Authenticator
 from szurubooru.middleware.json_translator import JsonTranslator
 from szurubooru.middleware.require_json import RequireJson
 from szurubooru.middleware.db_session import DbSession
+from szurubooru.middleware.imbue_context import ImbueContext
diff --git a/server/szurubooru/middleware/authenticator.py b/server/szurubooru/middleware/authenticator.py
index 37f743d0..58ed3572 100644
--- a/server/szurubooru/middleware/authenticator.py
+++ b/server/szurubooru/middleware/authenticator.py
@@ -1,9 +1,7 @@
-''' Exports Authenticator. '''
-
 import base64
 import falcon
-from szurubooru.model.user import User
-from szurubooru.errors import AuthError
+from szurubooru import errors
+from szurubooru import model
 
 class Authenticator(object):
     '''
@@ -15,7 +13,7 @@ class Authenticator(object):
         self._auth_service = auth_service
         self._user_service = user_service
 
-    def process_request(self, request, response):
+    def process_request(self, request, _response):
         ''' Executed before passing the request to the API. '''
         request.context.user = self._get_user(request)
         if request.get_param_as_bool('bump-login') \
@@ -51,13 +49,13 @@ class Authenticator(object):
         ''' Tries to authenticate user. Throws AuthError for invalid users. '''
         user = self._user_service.get_by_name(session, username)
         if not user:
-            raise AuthError('No such user.')
+            raise errors.AuthError('No such user.')
         if not self._auth_service.is_valid_password(user, password):
-            raise AuthError('Invalid password.')
+            raise errors.AuthError('Invalid password.')
         return user
 
     def _create_anonymous_user(self):
-        user = User()
+        user = model.User()
         user.name = None
         user.access_rank = 'anonymous'
         user.password = None
diff --git a/server/szurubooru/middleware/db_session.py b/server/szurubooru/middleware/db_session.py
index dff317e8..12bbad7d 100644
--- a/server/szurubooru/middleware/db_session.py
+++ b/server/szurubooru/middleware/db_session.py
@@ -1,16 +1,14 @@
-''' Exports DbSession. '''
-
 class DbSession(object):
     ''' Attaches database session to the context of every request. '''
 
     def __init__(self, session_factory):
         self._session_factory = session_factory
 
-    def process_request(self, request, response):
+    def process_request(self, request, _response):
         ''' Executed before passing the request to the API. '''
         request.context.session = self._session_factory()
 
-    def process_response(self, request, response, resource):
+    def process_response(self, request, _response, _resource):
         '''
         Executed before passing the response to falcon.
         Any commits to database need to happen explicitly in the API layer.
diff --git a/server/szurubooru/middleware/imbue_context.py b/server/szurubooru/middleware/imbue_context.py
new file mode 100644
index 00000000..da1a91da
--- /dev/null
+++ b/server/szurubooru/middleware/imbue_context.py
@@ -0,0 +1,8 @@
+class ImbueContext(object):
+    ''' Decorates context with methods from falcon's request. '''
+
+    def process_request(self, request, _response):
+        request.context.get_param_as_string = request.get_param_as_string
+        request.context.get_param_as_bool = request.get_param_as_bool
+        request.context.get_param_as_int = request.get_param_as_int
+        request.context.get_param_as_list = request.get_param_as_list
diff --git a/server/szurubooru/middleware/json_translator.py b/server/szurubooru/middleware/json_translator.py
index bed51720..cc42bf4c 100644
--- a/server/szurubooru/middleware/json_translator.py
+++ b/server/szurubooru/middleware/json_translator.py
@@ -1,12 +1,10 @@
-''' Exports JsonTranslator. '''
-
+import datetime
 import json
-from datetime import datetime
 import falcon
 
 def json_serial(obj):
     ''' JSON serializer for objects not serializable by default JSON code '''
-    if isinstance(obj, datetime):
+    if isinstance(obj, datetime.datetime):
         serial = obj.isoformat()
         return serial
     raise TypeError('Type not serializable')
@@ -17,7 +15,7 @@ class JsonTranslator(object):
     context.
     '''
 
-    def process_request(self, request, response):
+    def process_request(self, request, _response):
         ''' Executed before passing the request to the API. '''
         if request.content_length in (None, 0):
             return
@@ -37,7 +35,7 @@ class JsonTranslator(object):
                 'Could not decode the request body. The '
                 'JSON was incorrect or not encoded as UTF-8.')
 
-    def process_response(self, request, response, resource):
+    def process_response(self, request, response, _resource):
         ''' Executed before passing the response to falcon. '''
         if 'result' not in request.context:
             return
diff --git a/server/szurubooru/middleware/require_json.py b/server/szurubooru/middleware/require_json.py
index c5934267..ef901ca5 100644
--- a/server/szurubooru/middleware/require_json.py
+++ b/server/szurubooru/middleware/require_json.py
@@ -1,12 +1,10 @@
-''' Exports RequireJson. '''
-
 import falcon
 
 class RequireJson(object):
     ''' Sanitizes requests so that only JSON is accepted. '''
 
-    def process_request(self, req, resp):
+    def process_request(self, request, _response):
         ''' Executed before passing the request to the API. '''
-        if not req.client_accepts_json:
+        if not request.client_accepts_json:
             raise falcon.HTTPNotAcceptable(
                 'This API only supports responses encoded as JSON.')
diff --git a/server/szurubooru/model/user.py b/server/szurubooru/model/user.py
index f611a523..f5f5ecde 100644
--- a/server/szurubooru/model/user.py
+++ b/server/szurubooru/model/user.py
@@ -1,12 +1,9 @@
 # pylint: disable=too-many-instance-attributes,too-few-public-methods
 
-''' Exports User. '''
-
 import sqlalchemy as sa
 from szurubooru.model.base import Base
 
 class User(Base):
-    ''' Database representation of an user. '''
     __tablename__ = 'user'
 
     AVATAR_GRAVATAR = 1
diff --git a/server/szurubooru/services/auth_service.py b/server/szurubooru/services/auth_service.py
index f24dc9eb..1f4a4127 100644
--- a/server/szurubooru/services/auth_service.py
+++ b/server/szurubooru/services/auth_service.py
@@ -1,10 +1,6 @@
-''' Exports AuthService. '''
-
-from szurubooru.errors import AuthError
+from szurubooru import errors
 
 class AuthService(object):
-    ''' Services related to user authentication '''
-
     def __init__(self, config, password_service):
         self._config = config
         self._password_service = password_service
@@ -29,4 +25,4 @@ class AuthService(object):
         minimal_rank = self._config['privileges'][privilege_name]
         good_ranks = all_ranks[all_ranks.index(minimal_rank):]
         if user.access_rank not in good_ranks:
-            raise AuthError('Insufficient privileges to do this.')
+            raise errors.AuthError('Insufficient privileges to do this.')
diff --git a/server/szurubooru/services/mailer.py b/server/szurubooru/services/mailer.py
index 06e107a1..7e5d3b3a 100644
--- a/server/szurubooru/services/mailer.py
+++ b/server/szurubooru/services/mailer.py
@@ -1,12 +1,12 @@
 import smtplib
-from email.mime.text import MIMEText
+import email.mime.text
 
 class Mailer(object):
     def __init__(self, config):
         self._config = config
 
     def send(self, sender, recipient, subject, body):
-        msg = MIMEText(body)
+        msg = email.mime.text.MIMEText(body)
         msg['Subject'] = subject
         msg['From'] = sender
         msg['To'] = recipient
diff --git a/server/szurubooru/services/password_service.py b/server/szurubooru/services/password_service.py
index d330dd9c..f13da942 100644
--- a/server/szurubooru/services/password_service.py
+++ b/server/szurubooru/services/password_service.py
@@ -1,5 +1,3 @@
-''' Exports PasswordService. '''
-
 import hashlib
 import random
 
diff --git a/server/szurubooru/services/search/base_search_config.py b/server/szurubooru/services/search/base_search_config.py
index df2793fe..7aba690f 100644
--- a/server/szurubooru/services/search/base_search_config.py
+++ b/server/szurubooru/services/search/base_search_config.py
@@ -1,34 +1,32 @@
-''' Exports BaseSearchConfig. '''
-
 import sqlalchemy
-from szurubooru.errors import SearchError
-from szurubooru.services.search.criteria import *
-from szurubooru.util import parse_time_range
+import szurubooru.errors
+from szurubooru import util
+from szurubooru.services.search import criteria
 
 def _apply_criterion_to_column(
-    column, query, criterion, allow_composite=True, allow_ranged=True):
+        column, query, criterion, allow_composite=True, allow_ranged=True):
     ''' Decorates SQLAlchemy filter on given column using supplied criterion. '''
-    if isinstance(criterion, StringSearchCriterion):
-        filter = column == criterion.value
+    if isinstance(criterion, criteria.StringSearchCriterion):
+        expr = column == criterion.value
         if criterion.negated:
-            filter = ~filter
-        return query.filter(filter)
-    elif isinstance(criterion, ArraySearchCriterion):
+            expr = ~expr
+        return query.filter(expr)
+    elif isinstance(criterion, criteria.ArraySearchCriterion):
         if not allow_composite:
-            raise SearchError(
+            raise szurubooru.errors.SearchError(
                 'Composite token %r is invalid in this context.' % (criterion,))
-        filter = column.in_(criterion.values)
+        expr = column.in_(criterion.values)
         if criterion.negated:
-            filter = ~filter
-        return query.filter(filter)
-    elif isinstance(criterion, RangedSearchCriterion):
+            expr = ~expr
+        return query.filter(expr)
+    elif isinstance(criterion, criteria.RangedSearchCriterion):
         if not allow_ranged:
-            raise SearchError(
+            raise szurubooru.errors.SearchError(
                 'Ranged token %r is invalid in this context.' % (criterion,))
-        filter = column.between(criterion.min_value, criterion.max_value)
+        expr = column.between(criterion.min_value, criterion.max_value)
         if criterion.negated:
-            filter = ~filter
-        return query.filter(filter)
+            expr = ~expr
+        return query.filter(expr)
     else:
         raise RuntimeError('Invalid search type: %r.' % (criterion,))
 
@@ -37,36 +35,35 @@ def _apply_date_criterion_to_column(column, query, criterion):
     Decorates SQLAlchemy filter on given column using supplied criterion.
     Parses the datetime inside the criterion.
     '''
-    if isinstance(criterion, StringSearchCriterion):
-        min_date, max_date = parse_time_range(criterion.value)
-        filter = column.between(min_date, max_date)
+    if isinstance(criterion, criteria.StringSearchCriterion):
+        min_date, max_date = util.parse_time_range(criterion.value)
+        expr = column.between(min_date, max_date)
         if criterion.negated:
-            filter = ~filter
-        return query.filter(filter)
-    elif isinstance(criterion, ArraySearchCriterion):
-        result = query
-        filter = sqlalchemy.sql.false()
+            expr = ~expr
+        return query.filter(expr)
+    elif isinstance(criterion, criteria.ArraySearchCriterion):
+        expr = sqlalchemy.sql.false()
         for value in criterion.values:
-            min_date, max_date = parse_time_range(value)
-            filter = filter | column.between(min_date, max_date)
+            min_date, max_date = util.parse_time_range(value)
+            expr = expr | column.between(min_date, max_date)
         if criterion.negated:
-            filter = ~filter
-        return query.filter(filter)
-    elif isinstance(criterion, RangedSearchCriterion):
+            expr = ~expr
+        return query.filter(expr)
+    elif isinstance(criterion, criteria.RangedSearchCriterion):
         assert criterion.min_value or criterion.max_value
         if criterion.min_value and criterion.max_value:
-            min_date = parse_time_range(criterion.min_value)[0]
-            max_date = parse_time_range(criterion.max_value)[1]
-            filter = column.between(min_date, max_date)
+            min_date = util.parse_time_range(criterion.min_value)[0]
+            max_date = util.parse_time_range(criterion.max_value)[1]
+            expr = column.between(min_date, max_date)
         elif criterion.min_value:
-            min_date = parse_time_range(criterion.min_value)[0]
-            filter = column >= min_date
+            min_date = util.parse_time_range(criterion.min_value)[0]
+            expr = column >= min_date
         elif criterion.max_value:
-            max_date = parse_time_range(criterion.max_value)[1]
-            filter = column <= max_date
+            max_date = util.parse_time_range(criterion.max_value)[1]
+            expr = column <= max_date
         if criterion.negated:
-            filter = ~filter
-        return query.filter(filter)
+            expr = ~expr
+        return query.filter(expr)
 
 class BaseSearchConfig(object):
     def create_query(self, session):
diff --git a/server/szurubooru/services/search/criteria.py b/server/szurubooru/services/search/criteria.py
index 467cbfde..b7d47d84 100644
--- a/server/szurubooru/services/search/criteria.py
+++ b/server/szurubooru/services/search/criteria.py
@@ -1,4 +1,4 @@
-class BaseSearchCriterion(object):
+class _BaseSearchCriterion(object):
     def __init__(self, original_text, negated):
         self.original_text = original_text
         self.negated = negated
@@ -6,18 +6,18 @@ class BaseSearchCriterion(object):
     def __repr__(self):
         return self.original_text
 
-class RangedSearchCriterion(BaseSearchCriterion):
+class RangedSearchCriterion(_BaseSearchCriterion):
     def __init__(self, original_text, negated, min_value, max_value):
         super().__init__(original_text, negated)
         self.min_value = min_value
         self.max_value = max_value
 
-class StringSearchCriterion(BaseSearchCriterion):
+class StringSearchCriterion(_BaseSearchCriterion):
     def __init__(self, original_text, negated, value):
         super().__init__(original_text, negated)
         self.value = value
 
-class ArraySearchCriterion(BaseSearchCriterion):
+class ArraySearchCriterion(_BaseSearchCriterion):
     def __init__(self, original_text, negated, values):
         super().__init__(original_text, negated)
         self.values = values
diff --git a/server/szurubooru/services/search/search_executor.py b/server/szurubooru/services/search/search_executor.py
index 6d6a630f..f12b5398 100644
--- a/server/szurubooru/services/search/search_executor.py
+++ b/server/szurubooru/services/search/search_executor.py
@@ -2,8 +2,8 @@
 
 import re
 import sqlalchemy
-from szurubooru.errors import SearchError
-from szurubooru.services.search.criteria import *
+from szurubooru import errors
+from szurubooru.services.search import criteria
 
 class SearchExecutor(object):
     ORDER_DESC = 1
@@ -62,9 +62,11 @@ class SearchExecutor(object):
                 elif order_str == 'desc':
                     order = self.ORDER_DESC
                 else:
-                    raise SearchError('Unknown search direction: %r.' % order_str)
+                    raise errors.SearchError(
+                        'Unknown search direction: %r.' % order_str)
             else:
-                raise SearchError('Too many commas in order search token.')
+                raise errors.SearchError(
+                    'Too many commas in order search token.')
             if negated:
                 if order == self.ORDER_DESC:
                     order = self.ORDER_ASC
@@ -79,21 +81,22 @@ class SearchExecutor(object):
 
     def _handle_anonymous(self, query, criterion):
         if not self._search_config.anonymous_filter:
-            raise SearchError(
+            raise errors.SearchError(
                 'Anonymous tokens are not valid in this context.')
         return self._search_config.anonymous_filter(query, criterion)
 
     def _handle_named(self, query, key, criterion):
         if key in self._search_config.named_filters:
             return self._search_config.named_filters[key](query, criterion)
-        raise SearchError(
+        raise errors.SearchError(
             'Unknown named token: %r. Available named tokens: %r.' % (
                 key, list(self._search_config.named_filters.keys())))
 
     def _handle_special(self, query, value, negated):
         if value in self._search_config.special_filters:
-            return self._search_config.special_filters[value](query, criterion)
-        raise SearchError(
+            return self._search_config.special_filters[value](
+                query, value, negated)
+        raise errors.SearchError(
             'Unknown special token: %r. Available special tokens: %r.' % (
                 value, list(self._search_config.special_filters.keys())))
 
@@ -105,7 +108,7 @@ class SearchExecutor(object):
             else:
                 column = column.desc()
             return query.order_by(column)
-        raise SearchError(
+        raise errors.SearchError(
             'Unknown search order: %r. Available search orders: %r.' % (
                 value, list(self._search_config.order_columns.keys())))
 
@@ -113,8 +116,9 @@ class SearchExecutor(object):
         if '..' in value:
             low, high = value.split('..')
             if not low and not high:
-                raise SearchError('Empty ranged value')
-            return RangedSearchCriterion(value, negated, low, high)
+                raise errors.SearchError('Empty ranged value')
+            return criteria.RangedSearchCriterion(value, negated, low, high)
         if ',' in value:
-            return ArraySearchCriterion(value, negated, value.split(','))
-        return StringSearchCriterion(value, negated, value)
+            return criteria.ArraySearchCriterion(
+                value, negated, value.split(','))
+        return criteria.StringSearchCriterion(value, negated, value)
diff --git a/server/szurubooru/services/search/user_search_config.py b/server/szurubooru/services/search/user_search_config.py
index a9602d25..bd95ec6b 100644
--- a/server/szurubooru/services/search/user_search_config.py
+++ b/server/szurubooru/services/search/user_search_config.py
@@ -1,7 +1,6 @@
 ''' Exports UserSearchConfig. '''
 
 from sqlalchemy.sql.expression import func
-from szurubooru.errors import SearchError
 from szurubooru.model import User
 from szurubooru.services.search.base_search_config import BaseSearchConfig
 
diff --git a/server/szurubooru/services/user_service.py b/server/szurubooru/services/user_service.py
index 17812ddf..ca4f2214 100644
--- a/server/szurubooru/services/user_service.py
+++ b/server/szurubooru/services/user_service.py
@@ -1,10 +1,8 @@
-''' Exports UserService. '''
-
 import re
 from datetime import datetime
-from szurubooru.errors import ValidationError
-from szurubooru.model.user import User
-from szurubooru.util import is_valid_email
+from szurubooru import errors
+from szurubooru import model
+from szurubooru import util
 
 class UserService(object):
     ''' User management '''
@@ -19,29 +17,26 @@ class UserService(object):
         ''' Creates an user with given parameters and returns it. '''
 
         if not re.match(self._name_regex, name):
-            raise ValidationError(
+            raise errors.ValidationError(
                 'Name must satisfy regex %r.' % self._name_regex)
 
         if not re.match(self._password_regex, password):
-            raise ValidationError(
+            raise errors.ValidationError(
                 'Password must satisfy regex %r.' % self._password_regex)
 
-        if not is_valid_email(email):
-            raise ValidationError('%r is not a vaild email address.' % email)
+        if not util.is_valid_email(email):
+            raise errors.ValidationError(
+                '%r is not a vaild email address.' % email)
 
-        # prefer nulls to empty strings in the DB
-        if not email:
-            email = None
-
-        user = User()
+        user = model.User()
         user.name = name
         user.password_salt = self._password_service.create_password()
         user.password_hash = self._password_service.get_password_hash(
             user.password_salt, password)
-        user.email = email
+        user.email = email or None
         user.access_rank = self._config['service']['default_user_rank']
         user.creation_time = datetime.now()
-        user.avatar_style = User.AVATAR_GRAVATAR
+        user.avatar_style = model.User.AVATAR_GRAVATAR
 
         session.add(user)
         return user
@@ -58,4 +53,4 @@ class UserService(object):
 
     def get_by_name(self, session, name):
         ''' Retrieves an user by its name. '''
-        return session.query(User).filter_by(name=name).first()
+        return session.query(model.User).filter_by(name=name).first()
diff --git a/server/szurubooru/tests/api/test_updating_user.py b/server/szurubooru/tests/api/test_updating_user.py
index 1079865f..6ffa09ab 100644
--- a/server/szurubooru/tests/api/test_updating_user.py
+++ b/server/szurubooru/tests/api/test_updating_user.py
@@ -39,8 +39,6 @@ class TestUserDetailApi(DatabaseTestCase):
         self.context = dotdict()
         self.context.session = self.session
         self.context.request = {}
-        self.request = dotdict()
-        self.request.context = self.context
 
     def _create_user(self, name, rank='admin'):
         user = User()
@@ -58,7 +56,7 @@ class TestUserDetailApi(DatabaseTestCase):
         admin_user = self._create_user('u1', 'admin')
         self.session.add(admin_user)
         self.context.user = admin_user
-        self.api.put(self.request, self.context, 'u1')
+        self.api.put(self.context, 'u1')
         admin_user = self.session.query(User).filter_by(name='u1').one()
         self.assertEqual(admin_user.name, 'u1')
         self.assertEqual(admin_user.email, 'dummy')
@@ -74,7 +72,7 @@ class TestUserDetailApi(DatabaseTestCase):
             'password': 'valid',
             'accessRank': 'mod',
         }
-        self.api.put(self.request, self.context, 'u1')
+        self.api.put(self.context, 'u1')
         admin_user = self.session.query(User).filter_by(name='chewie').one()
         self.assertEqual(admin_user.name, 'chewie')
         self.assertEqual(admin_user.email, 'asd@asd.asd')
@@ -87,7 +85,7 @@ class TestUserDetailApi(DatabaseTestCase):
         self.session.add(admin_user)
         self.context.user = admin_user
         self.context.request = {'email': ''}
-        self.api.put(self.request, self.context, 'u1')
+        self.api.put(self.context, 'u1')
         admin_user = self.session.query(User).filter_by(name='u1').one()
         self.assertEqual(admin_user.email, None)
 
@@ -97,16 +95,16 @@ class TestUserDetailApi(DatabaseTestCase):
         self.context.user = admin_user
         self.context.request = {'name': '.'}
         self.assertRaises(
-            ValidationError, self.api.put, self.request, self.context, 'u1')
+            ValidationError, self.api.put, self.context, 'u1')
         self.context.request = {'password': '.'}
         self.assertRaises(
-            ValidationError, self.api.put, self.request, self.context, 'u1')
+            ValidationError, self.api.put, self.context, 'u1')
         self.context.request = {'accessRank': '.'}
         self.assertRaises(
-            ValidationError, self.api.put, self.request, self.context, 'u1')
+            ValidationError, self.api.put, self.context, 'u1')
         self.context.request = {'email': '.'}
         self.assertRaises(
-            ValidationError, self.api.put, self.request, self.context, 'u1')
+            ValidationError, self.api.put, self.context, 'u1')
 
     def test_user_trying_to_update_someone_else(self):
         user1 = self._create_user('u1', 'regular_user')
@@ -120,7 +118,7 @@ class TestUserDetailApi(DatabaseTestCase):
                 {'password': 'whatever'}]:
             self.context.request = request
             self.assertRaises(
-                AuthError, self.api.put, self.request, self.context, user2.name)
+                AuthError, self.api.put, self.context, user2.name)
 
     def test_user_trying_to_become_someone_else(self):
         user1 = self._create_user('u1', 'regular_user')
@@ -129,7 +127,7 @@ class TestUserDetailApi(DatabaseTestCase):
         self.context.user = user1
         self.context.request = {'name': 'u2'}
         self.assertRaises(
-            ValidationError, self.api.put, self.request, self.context, 'u1')
+            ValidationError, self.api.put, self.context, 'u1')
 
     def test_mods_trying_to_become_admin(self):
         user1 = self._create_user('u1', 'mod')
@@ -138,6 +136,6 @@ class TestUserDetailApi(DatabaseTestCase):
         self.context.user = user1
         self.context.request = {'accessRank': 'admin'}
         self.assertRaises(
-            AuthError, self.api.put, self.request, self.context, user1.name)
+            AuthError, self.api.put, self.context, user1.name)
         self.assertRaises(
-            AuthError, self.api.put, self.request, self.context, user2.name)
+            AuthError, self.api.put, self.context, user2.name)
diff --git a/server/szurubooru/tests/services/search/test_user_search_config.py b/server/szurubooru/tests/services/search/test_user_search_config.py
index c3cae960..148f79eb 100644
--- a/server/szurubooru/tests/services/search/test_user_search_config.py
+++ b/server/szurubooru/tests/services/search/test_user_search_config.py
@@ -1,18 +1,17 @@
 from datetime import datetime
-from szurubooru.errors import SearchError
-from szurubooru.model.user import User
-from szurubooru.services.search.search_executor import SearchExecutor
-from szurubooru.services.search.user_search_config import UserSearchConfig
+from szurubooru import errors
+from szurubooru import model
+from szurubooru.services import search
 from szurubooru.tests.database_test_case import DatabaseTestCase
 
 class TestUserSearchExecutor(DatabaseTestCase):
     def setUp(self):
         super().setUp()
-        self.search_config = UserSearchConfig()
-        self.executor = SearchExecutor(self.search_config)
+        self.search_config = search.UserSearchConfig()
+        self.executor = search.SearchExecutor(self.search_config)
 
     def _create_user(self, name):
-        user = User()
+        user = model.User()
         user.name = name
         user.password = 'dummy'
         user.password_salt = 'dummy'
@@ -20,7 +19,7 @@ class TestUserSearchExecutor(DatabaseTestCase):
         user.email = 'dummy'
         user.access_rank = 'dummy'
         user.creation_time = datetime.now()
-        user.avatar_style = User.AVATAR_GRAVATAR
+        user.avatar_style = model.User.AVATAR_GRAVATAR
         return user
 
     def _test(self, query, page, expected_count, expected_user_names):
@@ -60,7 +59,7 @@ class TestUserSearchExecutor(DatabaseTestCase):
             self._test('%s:2014-06..' % alias, 1, 2, ['u2', 'u3'])
             self._test('%s:..2014-06' % alias, 1, 2, ['u1', 'u2'])
             self.assertRaises(
-                SearchError, self.executor.execute, self.session, '%s:..', 1)
+                errors.SearchError, self.executor.execute, self.session, '%s:..', 1)
 
     def test_filter_by_negated_ranged_creation_time(self):
         user1 = self._create_user('u1')
@@ -116,7 +115,7 @@ class TestUserSearchExecutor(DatabaseTestCase):
 
     def test_filter_by_ranged_name(self):
         self.assertRaises(
-            SearchError, self.executor.execute, self.session, 'name:u1..u2', 1)
+            errors.SearchError, self.executor.execute, self.session, 'name:u1..u2', 1)
 
     def test_paging(self):
         self.executor.page_size = 1
@@ -161,4 +160,4 @@ class TestUserSearchExecutor(DatabaseTestCase):
 
     def test_special(self):
         self.assertRaises(
-            SearchError, self.executor.execute, self.session, 'special:-', 1)
+            errors.SearchError, self.executor.execute, self.session, 'special:-', 1)
diff --git a/server/szurubooru/tests/test_util.py b/server/szurubooru/tests/test_util.py
index bfa5218f..526b97c8 100644
--- a/server/szurubooru/tests/test_util.py
+++ b/server/szurubooru/tests/test_util.py
@@ -5,6 +5,7 @@ from szurubooru.util import parse_time_range
 from szurubooru.errors import ValidationError
 
 class FakeDatetime(datetime):
+    @staticmethod
     def now(tz=None):
         return datetime(1997, 1, 2, 3, 4, 5, tzinfo=tz)
 
@@ -15,28 +16,28 @@ class TestParseTime(unittest.TestCase):
     def test_today(self):
         szurubooru.util.datetime.datetime = FakeDatetime
         date_min, date_max = parse_time_range('today')
-        self.assertEquals(date_min, datetime(1997, 1, 2, 0, 0, 0))
-        self.assertEquals(date_max, datetime(1997, 1, 2, 23, 59, 59))
+        self.assertEqual(date_min, datetime(1997, 1, 2, 0, 0, 0))
+        self.assertEqual(date_max, datetime(1997, 1, 2, 23, 59, 59))
 
     def test_yesterday(self):
         szurubooru.util.datetime.datetime = FakeDatetime
         date_min, date_max = parse_time_range('yesterday')
-        self.assertEquals(date_min, datetime(1997, 1, 1, 0, 0, 0))
-        self.assertEquals(date_max, datetime(1997, 1, 1, 23, 59, 59))
+        self.assertEqual(date_min, datetime(1997, 1, 1, 0, 0, 0))
+        self.assertEqual(date_max, datetime(1997, 1, 1, 23, 59, 59))
 
     def test_year(self):
         date_min, date_max = parse_time_range('1999')
-        self.assertEquals(date_min, datetime(1999, 1, 1, 0, 0, 0))
-        self.assertEquals(date_max, datetime(1999, 12, 31, 23, 59, 59))
+        self.assertEqual(date_min, datetime(1999, 1, 1, 0, 0, 0))
+        self.assertEqual(date_max, datetime(1999, 12, 31, 23, 59, 59))
 
     def test_month(self):
         for text in ['1999-2', '1999-02']:
             date_min, date_max = parse_time_range(text)
-            self.assertEquals(date_min, datetime(1999, 2, 1, 0, 0, 0))
-            self.assertEquals(date_max, datetime(1999, 2, 28, 23, 59, 59))
+            self.assertEqual(date_min, datetime(1999, 2, 1, 0, 0, 0))
+            self.assertEqual(date_max, datetime(1999, 2, 28, 23, 59, 59))
 
     def test_day(self):
         for text in ['1999-2-6', '1999-02-6', '1999-2-06', '1999-02-06']:
             date_min, date_max = parse_time_range(text)
-            self.assertEquals(date_min, datetime(1999, 2, 6, 0, 0, 0))
-            self.assertEquals(date_max, datetime(1999, 2, 6, 23, 59, 59))
+            self.assertEqual(date_min, datetime(1999, 2, 6, 0, 0, 0))
+            self.assertEqual(date_max, datetime(1999, 2, 6, 23, 59, 59))
diff --git a/server/szurubooru/util.py b/server/szurubooru/util.py
index dee024f0..9407d37a 100644
--- a/server/szurubooru/util.py
+++ b/server/szurubooru/util.py
@@ -1,12 +1,10 @@
-''' Exports miscellaneous functions and data structures. '''
-
 import datetime
 import re
 from szurubooru.errors import ValidationError
 
 def is_valid_email(email):
     ''' Validates given email address. '''
-    return not email or re.match('^[^@]*@[^@]*\.[^@]*$', email)
+    return not email or re.match(r'^[^@]*@[^@]*\.[^@]*$', email)
 
 class dotdict(dict): # pylint: disable=invalid-name
     ''' dot.notation access to dictionary attributes. '''
@@ -28,24 +26,24 @@ def parse_time_range(value, timezone=datetime.timezone(datetime.timedelta())):
         now = datetime.datetime.now(tz=timezone)
         return (
             datetime.datetime(now.year, now.month, now.day, 0, 0, 0),
-            datetime.datetime(now.year, now.month, now.day, 0, 0, 0)
+            datetime.datetime(now.year, now.month, now.day, 0, 0, 0) \
                 + one_day - one_second)
 
     if value == 'yesterday':
         now = datetime.datetime.now(tz=timezone)
         return (
             datetime.datetime(now.year, now.month, now.day, 0, 0, 0) - one_day,
-            datetime.datetime(now.year, now.month, now.day, 0, 0, 0)
+            datetime.datetime(now.year, now.month, now.day, 0, 0, 0) \
                 - one_second)
 
-    match = re.match('^(\d{4})$', value)
+    match = re.match(r'^(\d{4})$', value)
     if match:
         year = int(match.group(1))
         return (
             datetime.datetime(year, 1, 1),
             datetime.datetime(year + 1, 1, 1) - one_second)
 
-    match = re.match('^(\d{4})-(\d{1,2})$', value)
+    match = re.match(r'^(\d{4})-(\d{1,2})$', value)
     if match:
         year = int(match.group(1))
         month = int(match.group(2))
@@ -53,7 +51,7 @@ def parse_time_range(value, timezone=datetime.timezone(datetime.timedelta())):
             datetime.datetime(year, month, 1),
             datetime.datetime(year, month + 1, 1) - one_second)
 
-    match = re.match('^(\d{4})-(\d{1,2})-(\d{1,2})$', value)
+    match = re.match(r'^(\d{4})-(\d{1,2})-(\d{1,2})$', value)
     if match:
         year = int(match.group(1))
         month = int(match.group(2))