Alembic-Migrationen, wenn einige Tabellen vorhanden sind

Question

Ich habe einige Migrationen in Alembic, und versuchen, alembic upgrade head auf meine aktuelle Datenbank für die Revision laufen, aber in einigen Fällen habe ich Tabellen, die bereits existiert, so habe ich einen Fehler:

alembic upgrade head 
INFO [alembic.runtime.migration] Context impl PostgresqlImpl. 
INFO [alembic.runtime.migration] Will assume transactional DDL. 
INFO [alembic.runtime.migration] Running upgrade -> 3137cf88d8c6, create tables 
Traceback (most recent call last): 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/sqlalchemy/engine/base.py", line 1182, in _execute_context 
    context) 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/sqlalchemy/engine/default.py", line 470, in do_execute 
    cursor.execute(statement, parameters) 
psycopg2.ProgrammingError: relation "City" already exists 


The above exception was the direct cause of the following exception: 

Traceback (most recent call last): 
    File "/home/toweya/.virtualenvs/numus3/bin/alembic", line 11, in <module> 
    sys.exit(main()) 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/alembic/config.py", line 479, in main 
    CommandLine(prog=prog).main(argv=argv) 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/alembic/config.py", line 473, in main 
    self.run_cmd(cfg, options) 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/alembic/config.py", line 456, in run_cmd 
    **dict((k, getattr(options, k, None)) for k in kwarg) 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/alembic/command.py", line 254, in upgrade 
    script.run_env() 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/alembic/script/base.py", line 416, in run_env 
    util.load_python_file(self.dir, 'env.py') 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/alembic/util/pyfiles.py", line 93, in load_python_file 
    module = load_module_py(module_id, path) 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/alembic/util/compat.py", line 64, in load_module_py 
    module_id, path).load_module(module_id) 
    File "<frozen importlib._bootstrap_external>", line 388, in _check_name_wrapper 
    File "<frozen importlib._bootstrap_external>", line 809, in load_module 
    File "<frozen importlib._bootstrap_external>", line 668, in load_module 
    File "<frozen importlib._bootstrap>", line 268, in _load_module_shim 
    File "<frozen importlib._bootstrap>", line 693, in _load 
    File "<frozen importlib._bootstrap>", line 673, in _load_unlocked 
    File "<frozen importlib._bootstrap_external>", line 665, in exec_module 
    File "<frozen importlib._bootstrap>", line 222, in _call_with_frames_removed 
    File "numus/env.py", line 68, in <module> 
    run_migrations_online() 
    File "numus/env.py", line 63, in run_migrations_online 
    context.run_migrations() 
    File "<string>", line 8, in run_migrations 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/alembic/runtime/environment.py", line 817, in run_migrations 
    self.get_context().run_migrations(**kw) 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/alembic/runtime/migration.py", line 323, in run_migrations 
    step.migration_fn(**kw) 
    File "/home/toweya/PycharmProjects/NumusPortal/portal/db_manage/numus/versions/3137cf88d8c6_create_tables.py", line 30, in upgrade 
    sa.Column('name', sa.String(64), nullable=False), 
    File "<string>", line 8, in create_table 
    File "<string>", line 3, in create_table 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/alembic/operations/ops.py", line 1106, in create_table 
    return operations.invoke(op) 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/alembic/operations/base.py", line 318, in invoke 
    return fn(self, operation) 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/alembic/operations/toimpl.py", line 101, in create_table 
    operations.impl.create_table(table) 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/alembic/ddl/impl.py", line 194, in create_table 
    self._exec(schema.CreateTable(table)) 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/alembic/ddl/impl.py", line 118, in _exec 
    return conn.execute(construct, *multiparams, **params) 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/sqlalchemy/engine/base.py", line 945, in execute 
    return meth(self, multiparams, params) 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/sqlalchemy/sql/ddl.py", line 68, in _execute_on_connection 
    return connection._execute_ddl(self, multiparams, params) 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/sqlalchemy/engine/base.py", line 1002, in _execute_ddl 
    compiled 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/sqlalchemy/engine/base.py", line 1189, in _execute_context 
    context) 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/sqlalchemy/engine/base.py", line 1393, in _handle_dbapi_exception 
    exc_info 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/sqlalchemy/util/compat.py", line 203, in raise_from_cause 
    reraise(type(exception), exception, tb=exc_tb, cause=cause) 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/sqlalchemy/util/compat.py", line 186, in reraise 
    raise value.with_traceback(tb) 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/sqlalchemy/engine/base.py", line 1182, in _execute_context 
    context) 
    File "/home/toweya/.virtualenvs/numus3/lib/python3.5/site-packages/sqlalchemy/engine/default.py", line 470, in do_execute 
    cursor.execute(statement, parameters) 
sqlalchemy.exc.ProgrammingError: (psycopg2.ProgrammingError) relation "City" already exists 
[SQL: '\nCREATE TABLE "City" (\n\tid SERIAL NOT NULL, \n\tgeoid INTEGER NOT NULL, \n\tname VARCHAR(64) NOT NULL, \n\tPRIMARY KEY (id), \n\tUNIQUE (geoid)\n)\n\n'] 

Wie kann ich vorhandene Tabellen ignorieren?
Das bedeutet soviel wie: wenn Tabelle vorhanden - fortsetzen, aber abbrechen nicht

Answer 1

Sie müssen Ihre Migration/Version floder oder für alembic gehen:

/path/to/prooject/alembic/versions/3137cf88d8c6.py 

und bearbeiten Sie die letzte Migration Skript durch das Skript zu entfernen um die Tabelle in der Upgrade-Funktion zu erstellen und die umgekehrte Aufgabe in der Downgrade-Funktion im selben Skript zu entfernen.

Wie gesagt in flask migrate:

The migration script needs to be reviewed and edited

Und ich zitiere dies aus alembic:

We review and modify these by hand as needed, then proceed normally.