驗證 BigQuery 表是否存在

Question

我有一個簡單的函數來確定表是否存在：

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

問題是，它會在此行table = bigquery_client.get_table(table_ref)上拋出 404，這是可以的，因為該表不應該存在。 但它不會繼續處理腳本的其余部分。 我試圖在try except解析它， try except包裝器，但它不起作用。 我將如何解析這個？

Answer 1

您的腳本沒有輸入異常子句，因為它引發了NotFound錯誤而不是HttpError 。

這應該有效：

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

Answer 2

參見BigQuery Python客戶端官方文檔中的示例： https : //googleapis.dev/python/bigquery/latest/usage/tables.html#getting-a-table

摘抄：

from google.cloud import bigquery
from google.cloud.exceptions import NotFound

client = bigquery.Client()
# table_id = "your-project.your_dataset.your_table"

try:
    client.get_table(table_id)  # Make an API request.
    print("Table {} already exists.".format(table_id))
except NotFound:
    print("Table {} is not found.".format(table_id))

Answer 3

嘗試使用除了 NotFound NotFound 定義在https://github.com/googleapis/google-cloud-python/blob/release-core-1.3.0/api_core/google/api_core/exceptions.py#L219