sql.py 文件源码

def custom_sql_for_model(model, style, connection):
    opts = model._meta
    app_dirs = []
    app_dir = apps.get_app_config(model._meta.app_label).path
    app_dirs.append(os.path.normpath(os.path.join(app_dir, 'sql')))

    # Deprecated location -- remove in Django 1.9
    old_app_dir = os.path.normpath(os.path.join(app_dir, 'models/sql'))
    if os.path.exists(old_app_dir):
        warnings.warn("Custom SQL location '<app_label>/models/sql' is "
                      "deprecated, use '<app_label>/sql' instead.",
                      RemovedInDjango19Warning)
        app_dirs.append(old_app_dir)

    output = []

    # Post-creation SQL should come before any initial SQL data is loaded.
    # However, this should not be done for models that are unmanaged or
    # for fields that are part of a parent model (via model inheritance).
    if opts.managed:
        post_sql_fields = [f for f in opts.local_fields if hasattr(f, 'post_create_sql')]
        for f in post_sql_fields:
            output.extend(f.post_create_sql(style, model._meta.db_table))

    # Find custom SQL, if it's available.
    backend_name = connection.settings_dict['ENGINE'].split('.')[-1]
    sql_files = []
    for app_dir in app_dirs:
        sql_files.append(os.path.join(app_dir, "%s.%s.sql" % (opts.model_name, backend_name)))
        sql_files.append(os.path.join(app_dir, "%s.sql" % opts.model_name))
    for sql_file in sql_files:
        if os.path.exists(sql_file):
            with io.open(sql_file, encoding=settings.FILE_CHARSET) as fp:
                output.extend(connection.ops.prepare_sql_script(fp.read(), _allow_fallback=True))
    return output