first commit

db/env.py

@@ -0,0 +1,142 @@
+from __future__ import with_statement
+import os
+from alembic import context
+from sqlalchemy import engine_from_config, pool
+from logging.config import fileConfig
+import logging
+import re
+
+USE_TWOPHASE = False
+
+# this is the Alembic Config object, which provides
+# access to the values within the .ini file in use.
+config = context.config
+
+# Interpret the config file for Python logging.
+# This line sets up loggers basically.
+fileConfig(config.config_file_name)
+logger = logging.getLogger('alembic.env')
+
+# gather section names referring to different
+# databases.  These are named "engine1", "engine2"
+# in the sample .ini file.
+db_names = config.get_main_option('databases')
+
+# add your model's MetaData objects here
+# for 'autogenerate' support.  These must be set
+# up to hold just those tables targeting a
+# particular database. table.tometadata() may be
+# helpful here in case a "copy" of
+# a MetaData is needed.
+# from myapp import mymodel
+# target_metadata = {
+#       'engine1':mymodel.metadata1,
+#       'engine2':mymodel.metadata2
+#}
+target_metadata = {}
+
+# other values from the config, defined by the needs of env.py,
+# can be acquired:
+# my_important_option = config.get_main_option("my_important_option")
+# ... etc.
+
+
+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.
+
+    """
+    # for the --sql use case, run migrations for each URL into
+    # individual files.
+
+    engines = {}
+    db_url = os.getenv('DATABASE_URL')
+    if db_url:
+        engines['heroku'] = {'url': db_url}
+    else:
+        for name in re.split(r',\s*', db_names):
+            engines[name] = rec = {}
+            rec['url'] = context.config.get_section_option(name,
+                                                "sqlalchemy.url")
+
+    for name, rec in engines.items():
+        logger.info("Migrating database %s" % name)
+        file_ = "%s.sql" % name
+        logger.info("Writing output to %s" % file_)
+        with open(file_, 'w') as buffer:
+            context.configure(url=rec['url'], output_buffer=buffer)
+            with context.begin_transaction():
+                context.run_migrations(engine_name=name)
+
+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.
+
+    """
+
+    # for the direct-to-DB use case, start a transaction on all
+    # engines, then run all migrations, then commit all transactions.
+
+    engines = {}
+    db_url = os.getenv('DATABASE_URL')
+    if db_url:
+        engines['heroku'] = rec = {}
+        rec['engine'] = engine_from_config(
+                                    {'sqlalchemy.url': db_url},
+                                    poolclass=pool.NullPool)
+    else:
+        for name in re.split(r',\s*', db_names):
+            engines[name] = rec = {}
+            rec['engine'] = engine_from_config(
+                                        context.config.get_section(name),
+                                        prefix='sqlalchemy.',
+                                        poolclass=pool.NullPool)
+
+    for name, rec in engines.items():
+        engine = rec['engine']
+        rec['connection'] = conn = engine.connect()
+
+        if USE_TWOPHASE:
+            rec['transaction'] = conn.begin_twophase()
+        else:
+            rec['transaction'] = conn.begin()
+
+    try:
+        for name, rec in engines.items():
+            logger.info("Migrating database %s" % name)
+            context.configure(
+                        connection=rec['connection'],
+                        upgrade_token="%s_upgrades" % name,
+                        downgrade_token="%s_downgrades" % name,
+                        target_metadata=target_metadata.get(name)
+                    )
+            context.run_migrations()
+
+        if USE_TWOPHASE:
+            for rec in engines.values():
+                rec['transaction'].prepare()
+
+        for rec in engines.values():
+            rec['transaction'].commit()
+    except:
+        for rec in engines.values():
+            rec['transaction'].rollback()
+        raise
+    finally:
+        for rec in engines.values():
+            rec['connection'].close()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()