Implement proper Alembic migration

server/szurubooru/migrations/versions/336a76ec1338_create_post_tables.py

@@ -20,7 +20,6 @@ def upgrade():
         sa.Column("id", sa.Integer(), nullable=False),
         sa.Column("user_id", sa.Integer(), nullable=True),
         sa.Column("creation_time", sa.DateTime(), nullable=False),
-        sa.Column("file_last_modified_time", sa.DateTime(), nullable=False),
         sa.Column("last_edit_time", sa.DateTime(), nullable=True),
         sa.Column("safety", sa.Unicode(length=32), nullable=False),
         sa.Column("type", sa.Unicode(length=32), nullable=False),

server/szurubooru/migrations/versions/46c358b0ca93_add_file_last_modified_time.py

@@ -1,22 +1,55 @@
-'''
+"""
 Add file last modified time
 
 Revision ID: 46c358b0ca93
 Created at: 2020-08-26 17:08:17.845827
-'''
+"""
 
 import sqlalchemy as sa
 from alembic import op
 
-
-
-revision = '46c358b0ca93'
-down_revision = '54de8acc6cef'
+revision = "46c358b0ca93"
+down_revision = "54de8acc6cef"
 branch_labels = None
 depends_on = None
 
+
 def upgrade():
-    pass
+    op.add_column(
+        "post",
+        sa.Column("file_last_modified_time", sa.DateTime(), nullable=True),
+    )
+
+    op.execute(
+        """
+        DO
+        $do$
+        DECLARE creation_time_candidate TIMESTAMP;
+        BEGIN
+        WHILE EXISTS (
+            SELECT creation_time from "post"
+            WHERE file_last_modified_time IS NULL
+        ) LOOP
+            FOR creation_time_candidate IN (
+                SELECT creation_time FROM "post"
+                WHERE file_last_modified_time IS NULL
+            ) LOOP
+                UPDATE "post"
+                SET file_last_modified_time = creation_time
+                WHERE
+                    NOT EXISTS (
+                        SELECT creation_time FROM "post"
+                        WHERE file_last_modified_time = creation_time_candidate
+                );
+            END LOOP;
+        END LOOP;
+        END
+        $do$
+        """
+    )
+
+    op.alter_column("post", "file_last_modified_time", nullable=False)
+
 
 def downgrade():
-    pass
+    op.drop_column("post", "file_last_modified_time")