alembic

tangsel/base/scripts/alembic/README

+Generic single-database configuration.
\ No newline at end of file

tangsel/base/scripts/alembic/env.py

+"""Pyramid bootstrap environment. """
+import logging
+import os
+import importlib.machinery
+from alembic import context
+from pyramid.paster import (
+    get_appsettings,
+    setup_logging,
+)
+from sqlalchemy import engine_from_config
+from opensipkd.base.models.meta import Base
+
+config = context.config
+
+setup_logging(config.config_file_name)
+
+settings = get_appsettings(config.config_file_name)
+logging.info(settings)
+target_metadata = Base.metadata
+
+current_dir = os.path.split(__file__)[0]
+helper_file = os.path.join(current_dir, 'helpers.py')
+loader = importlib.machinery.SourceFileLoader('alembic_helpers', helper_file)
+helpers = loader.load_module()
+
+version_table = 'alembic_models'
+version_table_schema = 'public'
+
+
+def run_migrations_offline():
+    """Run migrations in 'offline' mode.
+
+    This configures the context with just a URL
+    and not an Engine, though an Engine is acceptable
+    here as well.  By skipping the Engine creation
+    we don't even need a DBAPI to be available.
+
+    Calls to context.execute() here emit the given string to the
+    script output.
+
+    """
+    context.configure(url=settings['sqlalchemy.url'],
+                      version_table=version_table)
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online():
+    """Run migrations in 'online' mode.
+
+    In this scenario we need to create an Engine
+    and associate a connection with the context.
+
+    """
+    engine = engine_from_config(settings, prefix='sqlalchemy.')
+
+    connection = engine.connect()
+    context.configure(
+        connection=connection,
+        target_metadata=target_metadata,
+        helpers=helpers,
+        version_table=version_table,
+        version_table_schema=version_table_schema
+    )
+    try:
+        with context.begin_transaction():
+            context.run_migrations()
+    finally:
+        connection.close()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()
\ No newline at end of file

tangsel/base/scripts/alembic/helpers.py

+# http://www.derstappen-it.de/tech-blog/sqlalchemie-alembic-check-if-table-has-column
+
+from alembic import op
+from sqlalchemy.engine import reflection
+import sqlalchemy as sa
+
+def has_table(table, schema=None, insp=None):
+    if not insp:
+        engine = op.get_bind()
+        insp = reflection.Inspector.from_engine(engine)
+    return insp.has_table(table, schema=schema)
+
+
+def table_has_column(table, column, schema=None):
+    engine = op.get_bind()
+    insp = reflection.Inspector.from_engine(engine)
+    has_column = False
+
+    if has_table(table, schema, insp):
+        for col in insp.get_columns(table, schema=schema):
+            if column != col['name']:
+                continue
+            has_column = True
+    return has_column
+
+
+def fields_update(table, field, typ, schema="public"):
+    context = op.get_context()
+    helpers = context.opts['helpers']
+    if not helpers.table_has_column(table, field, schema):
+        op.add_column(table,
+                      sa.Column(field, typ), schema=schema)
\ No newline at end of file

tangsel/base/scripts/alembic/script.py.mako

+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = ${repr(up_revision)}
+down_revision = ${repr(down_revision)}
+branch_labels = ${repr(branch_labels)}
+depends_on = ${repr(depends_on)}
+
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+def upgrade():
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade():
+    ${downgrades if downgrades else "pass"}