server: added basic date taken functionality

- [server] created basic utility for resolving date taken @ `func/metadata.py`
- [server] utilize `func/metadata.py` in `func/posts.py`
- [server] created Alembic migration that adds `date_taken` column to `post`
- [server] updated `model/post.py:Post` to have new column

server/szurubooru/func/metadata.py

@@ -0,0 +1,12 @@
+from datetime import datetime
+from typing import Optional
+
+from exif import Image
+
+
+def resolve_date_taken(content: bytes) -> Optional[datetime]:
+    img = Image(content)
+
+    if img.has_exif and "datetime" in img.list_all():
+        return datetime.strptime(img.datetime, "%Y:%m:%d %H:%M:%S")
+    return None

server/szurubooru/func/posts.py

@@ -11,6 +11,7 @@ from szurubooru.func import (
     files,
     image_hash,
     images,
+    metadata,
     mime,
     pools,
     scores,
@@ -199,6 +200,7 @@ class PostSerializer(serialization.BaseSerializer):
             "notes": self.serialize_notes,
             "comments": self.serialize_comments,
             "pools": self.serialize_pools,
+            "dateTaken": self.serialize_date_taken,
         }
 
     def serialize_id(self) -> Any:
@@ -344,6 +346,9 @@ class PostSerializer(serialization.BaseSerializer):
             )
         ]
 
+    def serialize_date_taken(self) -> Any:
+        return self.post.date_taken
+
 
 def serialize_post(
     post: Optional[model.Post], auth_user: model.User, options: List[str] = []
@@ -669,6 +674,11 @@ def update_post_content(post: model.Post, content: Optional[bytes]) -> None:
             post.canvas_height = None
     setattr(post, "__content", content)
 
+    if post.type in [model.Post.TYPE_IMAGE, model.Post.TYPE_VIDEO]:
+        post.date_taken = metadata.resolve_date_taken(content)
+    else:
+        post.date_taken = None
+
 
 def update_post_thumbnail(
     post: model.Post, content: Optional[bytes] = None

server/szurubooru/migrations/versions/57aafb3bf9f0_add_date_taken.py

@@ -0,0 +1,24 @@
+"""
+add_date_taken
+
+Revision ID: 57aafb3bf9f0
+Created at: 2021-11-26 21:00:19.698012
+"""
+
+import sqlalchemy as sa
+from alembic import op
+
+revision = "57aafb3bf9f0"
+down_revision = "adcd63ff76a2"
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    op.add_column(
+        "post", sa.Column("date_taken", sa.DateTime(), nullable=True)
+    )
+
+
+def downgrade():
+    op.drop_column("post", "date_taken")

server/szurubooru/model/post.py

@@ -223,6 +223,9 @@ class Post(Base):
     canvas_height = sa.Column("image_height", sa.Integer)
     mime_type = sa.Column("mime-type", sa.Unicode(32), nullable=False)
 
+    # EXIF things
+    date_taken = sa.Column("date_taken", sa.DateTime, nullable=True)
+
     # foreign tables
     user = sa.orm.relationship("User")
     tags = sa.orm.relationship("Tag", backref="posts", secondary="post_tag")