验证BigQuery表是否存在

Question

我有一个简单的函数来确定表是否存在:

def check_users_usersmetadata_existence():
    """
    Checks if the table Prod_UserUserMetadata exists
    """
    app_id = get_app_id()
    bigquery_client = bigquery.Client(project=app_id)
    dataset_ref = bigquery_client.dataset('Backup')
    table_ref = dataset_ref.table('Prod_UserUserMetadata')
    try:
        table = bigquery_client.get_table(table_ref)
        if table:
            print('Table {}\'s existence sucessfully proved!'.format(table_ref))
            return True
    except HttpError as error:
        raise
        print('Whoops! Table {} doesn\'t exist here! Ref: {}'.format(table_ref, error.resp.status))
        return False

问题是,它在这一行上抛出404,这table = bigquery_client.get_table(table_ref)是好的,因为该表不应该存在.但它不会继续处理脚本的其余部分.我试图在try except包装器中解析它,但它不起作用.我该怎么解析这个？

Answer 1

您的脚本没有输入异常子句,因为它引发了NotFound错误,而不是a HttpError.

这应该工作:

from google.cloud.exceptions import NotFound
def check_users_usersmetadata_existence():
    # (...)
    try:
        table = bigquery_client.get_table(table_ref)
        if table:
            print('Table {}\'s existence sucessfully proved!'.format(table_ref))
            return True
    except NotFound as error:
        # ...do some processing ...
        print('Whoops! Table {} doesn\'t exist here! Ref: {}'.format(table_ref, error.resp.status))
        return False