Downgrades the 'all files only on disk' migration

tracim/migration/versions/f3852e1349c4_all_files_only_on_disk.py

 
 """
 
+from alembic import context
 from alembic import op
+from depot.fields.sqlalchemy import UploadedFileField
+from depot.manager import DepotManager
 import sqlalchemy as sa
+from sqlalchemy.sql.expression import func
 
 # revision identifiers, used by Alembic.
 revision = 'f3852e1349c4'
 down_revision = '913efdf409e5'
 
 
+def configure_depot():
+    """Configure Depot."""
+    depot_storage_name = context.config.get_main_option('depot_storage_name')
+    depot_storage_path = context.config.get_main_option('depot_storage_dir')
+    depot_storage_settings = {'depot.storage_path': depot_storage_path}
+    DepotManager.configure(
+        depot_storage_name,
+        depot_storage_settings,
+    )
+
+
+revision_helper = sa.Table(
+    'content_revisions',
+    sa.MetaData(),
+    sa.Column('revision_id', sa.Integer, primary_key=True),
+    sa.Column('label', sa.String(1024), nullable=False),
+    sa.Column('file_extension', sa.String(255), nullable=False),
+    sa.Column('file_mimetype', sa.String(255), nullable=False),
+    sa.Column('file_content', sa.LargeBinary),
+    sa.Column('depot_file', UploadedFileField, nullable=True),
+    sa.Column('type', sa.String(32), nullable=False),
+)
+
+
 def upgrade():
     """Drops the file content from revision."""
     with op.batch_alter_table('content_revisions') as batch_op:
     """Adds the file content in revision."""
     with op.batch_alter_table('content_revisions') as batch_op:
         batch_op.add_column(sa.Column('file_content', sa.LargeBinary))
+
+    configure_depot()
+    depot = DepotManager.get()
+    connection = op.get_bind()
+    select_query = revision_helper.select() \
+        .where(revision_helper.c.type == 'file') \
+        .where(revision_helper.c.depot_file.isnot(None)) \
+        .where(func.length(revision_helper.c.depot_file) > 0)
+    files = connection.execute(select_query).fetchall()
+    for file in files:
+        depot_file_content = depot.get(file.depot_file)
+        update_query = revision_helper.update() \
+            .where(revision_helper.c.revision_id == file.revision_id) \
+            .values(file_content=depot_file_content)
+        connection.execute(update_query)