串流疊代器

呼叫 GoogleAdsService.search_stream 時，系統會傳回串流回應疊代器。使用這個迭代器時，應與 GoogleAdsService 用戶端保持在相同範圍，以免資料流中斷或發生區隔錯誤。這是因為開啟的 GoogleAdsService 物件超出範圍後，gRPC Channel 物件就會遭到垃圾收集。如果 GoogleAdsService 物件在 search_stream 結果上發生疊代時已不在範圍內，則 Channel 物件可能已遭破壞，導致疊代器嘗試擷取下一個值時發生未定義的行為。

下列程式碼示範錯誤的串流迭代器用法：

def stream_response(client, customer_id, query):
    return client.get_service("GoogleAdsService", version="v21").search_stream(customer_id, query=query)

def main(client, customer_id):
    query = "SELECT campaign.name FROM campaign LIMIT 10"
    response = stream_response(client, customer_id, query=query)
    # Access the iterator in a different scope from where the service object was created.
    try:
        for batch in response:
            # Iterate through response, expect undefined behavior.

在上述程式碼中，GoogleAdsService 物件是在與存取迭代器不同的範圍內建立。因此，迭代器可能會在耗用整個回應前，就將 Channel 物件毀損。

相反地，串流迭代器應與 GoogleAdsService 用戶端保持在相同範圍內，只要使用該迭代器即可：

def main(client, customer_id):
    ga_service = client.get_service("GoogleAdsService", version="v21")
    query = "SELECT campaign.name FROM campaign LIMIT 10"
    response = ga_service.search_stream(customer_id=customer_id, query=query)
    # Access the iterator in the same scope as where the service object was created.
    try:
        for batch in response:
            # Successfully iterate through response.