在 Google Ads API 中，更新作業是透過欄位遮罩完成。欄位遮罩會列出您打算透過更新作業變更的所有欄位，即使指定欄位傳送至伺服器，系統也會忽略不在欄位遮罩中的欄位。您可以手動建立欄位遮罩，方法是建立 FieldMask (Google\Protobuf\FieldMask)，建立包含所有要變更欄位名稱的陣列，然後將該陣列指派給欄位遮罩的 paths 欄位。
您也可以使用內建的欄位遮罩公用程式 (FieldMasks)，隱藏許多特定詳細資料，並檢查您對實體欄位所做的變更，自動產生欄位遮罩。
以下是更新廣告活動的範例：
$campaign = new Campaign([
'resource_name' => ResourceNames::forCampaign($customerId, $campaignId),
'status' => CampaignStatusEnum\CampaignStatus::PAUSED
]);
$campaignOperation = new CampaignOperation();
$campaignOperation->setUpdate($campaign);
$campaignOperation->setUpdateMask(FieldMasks::allSetFieldsOf($campaign));
這段程式碼會先建立 Campaign 物件，然後使用 ResourceNames 設定資源名稱，讓 API 知道要更新哪個廣告活動。status 也會設為 CampaignStatus::PAUSED。
接著，程式碼會建立 CampaignOperation 物件，並在該物件上設定先前建立的廣告活動。接著，它會使用 FieldMasks::allSetFieldsOf() 列舉所有已修改的欄位，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，FieldMasks::allSetFieldsOf() 是 FieldMasks::compare() 的便利方法。這個方法會將您傳遞的物件與相同類別的空白物件進行比較。舉例來說，在先前的程式碼中，您可以使用 FieldMasks::compare(new Campaign(), $campaign)，而非 FieldMasks::allSetFieldsOf($campaign)。
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 target_cpa_micros、cpc_bid_ceiling_micros 和 cpc_bid_floor_micros 等子欄位)，也可以完全沒有子欄位 (例如 ManualCpm)。
沒有定義子欄位的訊息欄位
更新未定義任何子欄位的 MESSAGE 欄位時，請使用 FieldMasks 產生欄位遮罩，如先前所述。
定義子欄位的訊息欄位
更新以子欄位定義的 MESSAGE 欄位時，如未明確設定該訊息的任何子欄位，您必須手動將每個可變動的 MESSAGE 子欄位新增至 FieldMask，類似於先前從頭建立欄位遮罩的範例。
常見的例子是更新廣告活動的出價策略，但未在新出價策略中設定任何欄位。下列程式碼示範如何更新廣告活動，以使用 MaximizeConversions 出價策略，而不設定出價策略的任何子欄位。
在這種情況下，使用 FieldMasks 的 allSetFieldsOf() 和 compare() 方法無法達成預期目標。
下列程式碼會產生包含 maximize_conversions 的欄位遮罩。不過，為避免不小心清除欄位，Google Ads API 不允許這種行為，並會產生 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 includes 'maximize_conversions',
// which produces 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 results in a
// FieldMaskError.FIELD_HAS_SUBFIELDS error because empty MESSAGE fields cannot
// be included in a field mask.
$campaignServiceClient = $googleAdsClient->getCampaignServiceClient();
$response = $campaignServiceClient->mutateCampaigns(
MutateCampaignsRequest::build($customerId, [$campaignOperation])
);
下列程式碼示範如何正確更新廣告活動，以使用 MaximizeConversions 出價策略，而不設定任何子欄位。
// 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 the mutable
// subfield 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 sets 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:
// https://developers.google.com/google-ads/api/docs/campaigns/bidding/assign-strategies
$fieldMask->getPaths()[] = '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);
清除欄位
部分欄位可明確清除。與先前的範例類似，您必須明確將這些欄位新增至欄位遮罩，因為 FieldMasks 會忽略設為預設值的 Proto3 純量欄位 (例如 0、false 或 "")。舉例來說，假設您有一個廣告活動採用 MaximizeConversions 出價策略，且 target_cpa_micros 欄位設為大於 0 的值。
下列程式碼會執行，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_micros' => 0
]),
'status' => CampaignStatusEnum\CampaignStatus::PAUSED
]);
// Constructs an operation, using the FieldMasks' allSetFieldsOf utility to
// derive the update mask. However, the field mask does 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 succeeds, but does NOT update
// the 'target_cpa_micros' field because
// 'maximize_conversions.target_cpa_micros' was not included in the field mask.
$campaignServiceClient = $googleAdsClient->getCampaignServiceClient();
$response = $campaignServiceClient->mutateCampaigns(
MutateCampaignsRequest::build($customerId, [$campaignOperation])
);
下列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
// clears this field from the bidding strategy without impacting any other
// fields on the bidding strategy.
$fieldMask = FieldMasks::allSetFieldsOf($campaign);
$fieldMask->getPaths()[] = '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，如果欄位在 Google Ads API 通訊協定緩衝區中定義為 optional，設定預設值會如預期運作。不過，由於 target_cpa_micros 不是 optional 欄位，因此將其設為 0，但未明確將路徑新增至欄位遮罩，不會更新出價策略來清除 target_cpa_micros。