欄位遮罩

在 Google Ads API 中，系統會使用欄位遮罩來更新資料。欄位遮罩會列出您要隨更新變更的所有欄位，並且忽略任何不在欄位遮罩中的指定欄位，即使傳送至伺服器也一樣。您可以手動建立欄位遮罩，方法是建立 Google\Protobuf\FieldMask，將您要變更的所有欄位名稱填入陣列，然後將該陣列指派給欄位遮罩的路徑欄位。

您也可以使用我們的內建欄位遮罩公用程式 (FieldMasks)，該公用程式會隱藏許多特定詳細資料，並藉由監控實體欄位的變更來自動產生欄位遮罩。

以下舉例說明如何更新廣告活動：

    $campaign = new Campaign([
        'resource_name' => ResourceNames::forCampaign($customerId, $campaignId),
        'status' => CampaignStatus::PAUSED
    ]);

    $campaignOperation = new CampaignOperation();
    $campaignOperation->setUpdate($campaign);
    $campaignOperation->setUpdateMask(FieldMasks::allSetFieldsOf($campaign));

此程式碼會先建立 Campaign 物件，然後使用 ResourceNames 設定其資源名稱，讓 API 知道要更新哪一個廣告活動。status 也設為 PAUSED。

接著，程式碼會建立 CampaignOperation 物件，並將先前建立的廣告活動設為該物件。之後，系統會運用 FieldMasks::allSetFieldsOf() 並使用所有已變更的欄位，為廣告活動建立欄位遮罩。最後，它會將傳回的遮罩傳遞至廣告活動作業物件。

請注意，對 FieldMasks::compare() 來說，FieldMasks::allSetFieldsOf 是簡便的方法。它會將傳遞的物件與相同類別的空白物件進行比較。例如，在先前的程式碼中，您可以使用 FieldMasks::compare(new Campaign(), $campaign) 而非 allSetFieldsOf()。

更新訊息欄位及其子欄位

MESSAGE 欄位可以有子欄位 (例如 MaximizeConversions，其中包含三個：target_cpa_micros、cpc_bid_ceiling_micros 和 cpc_bid_floor_micros)，也可以全部設為任何子欄位 (例如 ManualCpm)。

未定義子欄位的訊息欄位

更新未以任何子欄位定義的 MESSAGE 欄位時，請使用 FieldMasks 產生欄位遮罩，如上所述。

具有已定義子欄位的訊息欄位

更新透過子欄位定義的 MESSAGE 欄位時，如果未明確設定該訊息中的任何子欄位，您必須手動將每個「可變動」MESSAGE 子欄位新增至 FieldMask，類似之前建立欄位遮罩的範例。

更新廣告活動出價策略的常見例子之一，就是沒有為新出價策略設定任何欄位。以下程式碼示範如何將廣告活動改為使用 MaximizeConversions 出價策略，而不在出價策略上設定任何子欄位。

在這種情況下，使用 FieldMasks 的 allSetFieldsOf() 和 compare() 方法無法達成預期目標。

以下程式碼會產生包含 maximize_conversions 的欄位遮罩。但 Google Ads API 不允許這個行為，以免意外清除欄位並產生 FieldMaskError.FIELD_HAS_SUBFIELDS 錯誤。

// Creates a campaign with the proper resource name and an empty
// MaximizeConversions field.
$campaign = new Campaign([
    'resource_name' => ResourceNames::forCampaign($customerId, $campaignId),
    'maximize_conversions' => new MaximizeConversions()
]);

// Constructs an operation, using the FieldMasks' allSetFieldsOf utility to
// derive the update mask. The field mask will include 'maximize_conversions`,
// which will produce a FieldMaskError.FIELD_HAS_SUBFIELDS error.
$campaignOperation = new CampaignOperation();
$campaignOperation->setUpdate($campaign);
$campaignOperation->setUpdateMask(FieldMasks::allSetFieldsOf($campaign));

// Sends the operation in a mutate request that will result in a
// FieldMaskError.FIELD_HAS_SUBFIELDS error because empty MESSAGE fields cannot
// be included in a field mask.
$campaignServiceClient = $googleAdsClient->getCampaignServiceClient();
$response = $campaignServiceClient->mutateCampaigns($customerId, [$campaignOperation]);

以下程式碼示範如何正確更新廣告活動，以便在不設定任何子欄位的情況下，使用 MaximizeConversions 出價策略。

// Creates a Campaign object with the proper resource name.
$campaign = new Campaign([
    'resource_name' => ResourceNames::forCampaign($customerId, $campaignId)
]);

// Creates a field mask from the existing campaign and adds all of the mutable
// fields (only one in this case) on the MaximizeConversions bidding strategy to
// the field mask. Because this field is included in the field mask but
// excluded from the campaign object, the Google Ads API will set the campaign's
// bidding strategy to a MaximizeConversions object without any of its subfields
// set.
fieldMask = FieldMasks::allSetFieldsOf($campaign);
// Only include 'maximize_conversions.target_cpa_micros' in the field mask
// as it is the only mutable subfield on MaximizeConversions when used as a
// standard bidding strategy.
//
// Learn more about standard and portfolio bidding strategies here:
// https://developers.google.com/google-ads/api/docs/campaigns/bidding/assign-strategies
$fieldMask->setPaths(array_merge(
    iterator_to_array($fieldMask->getPaths()->getIterator()),
    ['maximize_conversions.target_cpa_micros']
));

// Creates an operation to update the campaign with the specified fields.
$campaignOperation = new CampaignOperation();
$campaignOperation->setUpdate($campaign);
$campaignOperation->setUpdateMask($fieldMask);

正在清除欄位

部分欄位可明確清除。與前述範例類似，您必須明確將這些欄位新增至欄位遮罩。舉例來說，假設您的廣告活動採用 MaximizeConversions 出價策略，且 target_cpa_micros 欄位設定的值大於 0。

系統會執行下列程式碼，但 maximize_conversions.target_cpa_micros 不會新增至欄位遮罩，因此 target_cpa_micros 欄位不會有任何變更：

// Creates a campaign with the proper resource name and a MaximizeConversions
// object with target_cpa_micros set to 0.
$campaign = new Campaign([
    'resource_name' => ResourceNames::forCampaign($customerId, $campaignId),
    'maximize_conversions' => new MaximizeConversions(['target_cpa' => 0]),
    'status' => CampaignStatus::PAUSED
]);

// Constructs an operation, using the FieldMasks' allSetFieldsOf utility to
// derive the update mask. However, the field mask will NOT include
// 'maximize_conversions.target_cpa_micros'.
$campaignOperation = new CampaignOperation();
$campaignOperation->setUpdate($campaign);
$campaignOperation->setUpdateMask(FieldMasks::allSetFieldsOf($campaign));

// Sends the operation in a mutate request that will succeed but will NOT update
// the 'target_cpa_micros' field because
// 'maximize_conversions.target_cpa_micros' was not included in the field mask.
$campaignServiceClient = $googleAdsClient->getCampaignServiceClient();
$response = $campaignServiceClient->mutateCampaigns($customerId, [$campaignOperation]);

以下程式碼示範如何正確清除 MaximizeConversions 出價策略中的 target_cpa_micros 欄位。

// Creates a Campaign object with the proper resource name.
$campaign = new Campaign([
    'resource_name' => ResourceNames::forCampaign($customerId, $campaignId)
]);

// Constructs a field mask from the existing campaign and adds the
// 'maximize_conversions.target_cpa_micros' field to the field mask, which will
// clear this field from the bidding strategy without impacting any other fields
// on the bidding strategy.
$fieldMask = FieldMasks::allSetFieldsOf($campaign);
$fieldMask->setPaths(array_merge(
    iterator_to_array($fieldMask->getPaths()->getIterator()),
    ['maximize_conversions.target_cpa_micros']
));

// Creates an operation to update the campaign with the specified field.
$campaignOperation = new CampaignOperation();
$campaignOperation->setUpdate($campaign);
$campaignOperation->setUpdateMask($fieldMask);

請注意，「錯誤」程式碼適用於在 Google Ads API protocol buffers 中定義為 optional 的欄位。但由於 target_cpa_micros 不是 optional 欄位，因此「錯誤」程式碼「不會」更新出價策略來清除 target_cpa 欄位。