Add downloads column to Package

Fixes #200

migrations/versions/c141a63b2487_.py

@@ -0,0 +1,38 @@
+"""empty message
+
+Revision ID: c141a63b2487
+Revises: cb6ab141c522
+Create Date: 2020-07-09 00:05:39.845465
+
+"""
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy import orm, func
+from app.models import Package, PackageRelease
+
+
+# revision identifiers, used by Alembic.
+revision = 'c141a63b2487'
+down_revision = 'cb6ab141c522'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+	op.add_column('package', sa.Column('downloads', sa.Integer(), nullable=False, server_default="0"))
+
+	bind = op.get_bind()
+	session = orm.Session(bind=bind)
+
+	for package in session.query(Package).all():
+		downloads_result = session.query(func.sum(PackageRelease.downloads)).filter_by(package_id=package.id).one_or_none()
+		downloads = 0 if not downloads_result or not downloads_result[0] else downloads_result[0]
+		package.downloads = downloads
+
+	session.commit()
+
+
+def downgrade():
+	# ### commands auto generated by Alembic - please adjust! ###
+	op.drop_column('package', 'downloads')
+	# ### end Alembic commands ###