SQLAlchemy - Getting a list of tables

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青春惊慌失措
青春惊慌失措 2020-12-08 03:40

I couldn\'t find any information about this in the documentation, but how can I get a list of tables created in SQLAlchemy?

I used the class method to create the tab

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  • 2020-12-08 04:18

    There is a method in engine object to fetch the list of tables name. engine.table_names()

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  • 2020-12-08 04:18

    Reflecting All Tables at Once allows you to retrieve hidden table names too. I created some temporary tables and they showed up with

    meta = MetaData()
    meta.reflect(bind=myengine)
    for table in reversed(meta.sorted_tables):
        print table
    

    Reference http://docs.sqlalchemy.org/en/latest/core/reflection.html

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  • 2020-12-08 04:21

    All of the tables are collected in the tables attribute of the SQLAlchemy MetaData object. To get a list of the names of those tables:

    >>> metadata.tables.keys()
    ['posts', 'comments', 'users']
    

    If you're using the declarative extension, then you probably aren't managing the metadata yourself. Fortunately, the metadata is still present on the baseclass,

    >>> Base = sqlalchemy.ext.declarative.declarative_base()
    >>> Base.metadata
    MetaData(None)
    

    If you are trying to figure out what tables are present in your database, even among the ones you haven't even told SQLAlchemy about yet, then you can use table reflection. SQLAlchemy will then inspect the database and update the metadata with all of the missing tables.

    >>> metadata.reflect(engine)
    

    For Postgres, if you have multiple schemas, you'll need to loop thru all the schemas in the engine:

    from sqlalchemy import inspect
    inspector = inspect(engine)
    schemas = inspector.get_schema_names()
    
    for schema in schemas:
        print("schema: %s" % schema)
        for table_name in inspector.get_table_names(schema=schema):
            for column in inspector.get_columns(table_name, schema=schema):
                print("Column: %s" % column)
    
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