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以更新變更的所有欄位，即使傳送至伺服器遮罩，系統仍會忽略任何不在欄位遮罩中的指定欄位。

FieldMaskUtil

產生欄位遮罩的建議做法是使用內建的欄位遮罩公用程式，也就是說，您可以使用已修改的物件產生欄位遮罩，而非從頭開始建構遮罩。

以下舉例說明如何更新廣告活動：

// Creates a Campaign object with the proper resource name and any other changes.
Campaign campaign =
    Campaign.newBuilder()
        .setResourceName(ResourceNames.campaign(customerId, campaignId))
        .setStatus(CampaignStatus.PAUSED)
        .build();

// Constructs an operation that will update the campaign, using the FieldMasks'
// allSetFieldsOf utility to derive the update mask. This mask tells the Google
// Ads API which attributes of the campaign you want to change.
CampaignOperation operation =
    CampaignOperation.newBuilder()
        .setUpdate(campaign)
        .setUpdateMask(FieldMasks.allSetFieldsOf(campaign))
        .build();

// Sends the operation in a mutate request.
MutateCampaignsResponse response =
    campaignServiceClient.mutateCampaigns(
        customerId.toString(), Collections.singletonList(operation));

此範例會先建立空白的 Campaign 物件，然後設定其資源名稱，讓 API 知道要更新哪個廣告活動。

此範例會在廣告活動使用 FieldMasks.allSetFieldsOf() 方法，自動產生用來列舉所有集合欄位的欄位遮罩。然後再將傳回的遮罩直接傳遞至更新呼叫。

如果您需要使用現有物件更新幾個欄位，可以按照下列步驟修改程式碼：

Campaign existingCampaign;

// Obtains existingCampaign from elsewhere.
...

// Creates a new campaign based off the existing campaign and updates the
// campaign by setting its status to paused.
Campaign campaignToUpdate =
    existingCampaign.toBuilder()
        .setStatus(CampaignStatus.PAUSED)
        .build();

// Constructs an operation that will update the campaign, using the FieldMasks'
// compare utility to derive the update mask. This mask tells the Google Ads API
// which attributes of the campaign you want to change.
CampaignOperation operation =
    CampaignOperation.newBuilder()
        .setUpdate(campaignToUpdate)
        .setUpdateMask(FieldMasks.compare(existingCampaign, campaignToUpdate))
        .build();

// Sends the operation in a mutate request.
MutateCampaignsResponse response =
    campaignServiceClient.mutateCampaigns(
        customerId.toString(), Collections.singletonList(operation));

如要從頭開始建立欄位遮罩，請先建立 FieldMask 物件，然後逐一為要變更物件的各個欄位新增名稱。

FieldMask fieldMask =
    FieldMask.newBuilder()
        .addPaths("status")
        .addPaths("name")
        .build();

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

如果更新未以任何子欄位定義的 MESSAGE 欄位，請使用 FieldMaskUtil 來產生欄位遮罩，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，類似上方用於從頭開始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。以下範例說明如何更新廣告活動，以便使用 MaximizeConversions 出價策略，但無須在出價策略中設定任何子欄位。

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

以下範例會產生包含 maximize_conversions 的欄位遮罩。不過，Google Ads API 不允許執行這個行為，以免意外清除欄位並產生 FieldMaskError.FIELD_HAS_SUBFIELDS 錯誤。

警告： 下列程式碼會產生錯誤。

// Creates a campaign with the proper resource name and an empty
// MaximizeConversions field.
Campaign campaign = Campaign.newBuilder()
    .setResourceName(ResourceNames.campaign(customerId, campaignId))
    .setMaximizeConversions(MaximizeConversions.newBuilder().build())
    .build();

// 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 operation =
    CampaignOperation.newBuilder()
        .setUpdate(campaign)
        .setUpdateMask(FieldMasks.allSetFieldsOf(campaign))
        .build();

// 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.
MutateCampaignsResponse response =
    campaignServiceClient.mutateCampaigns(
        customerId.toString(), Collections.singletonList(operation));

以下範例說明如何正確更新廣告活動，以便使用 MaximizeConversions 出價策略，而無須設定任何子欄位。

成功： 下方程式碼能成功更新廣告活動出價策略。

// Creates a Campaign object with the proper resource name.
Campaign campaign = Campaign.newBuilder()
    .setResourceName(ResourceNames.campaign(customerId, campaignId))
    .build();

// 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 fieldMask = FieldMasks.allSetFieldsOf(campaign)
    .toBuilder()
    // 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
    .addPaths("maximize_conversions.target_cpa_micros")
    .build();

// Creates an operation to update the campaign with the specified fields.
CampaignOperation operation =
    CampaignOperation.newBuilder()
        .setUpdate(campaign)
        .setUpdateMask(fieldMask)
        .build();

清除欄位

部分欄位可明確清除。與上述範例類似，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：

警告： 這個程式碼不會產生錯誤，但 MaximizeConversions 出價策略的 target_cpa_micros 不會清除。

// Creates a campaign with the proper resource name and a MaximizeConversions
// object with target_cpa_micros set to 0.
Campaign campaign =
    Campaign.newBuilder()
        .setResourceName(ResourceNames.campaign(customerId, campaignId))
        .setMaximizeConversions(
            MaximizeConversions.newBuilder().setTargetCpa(0).build())
        .setStatus(CampaignStatus.PAUSED)
        .build();

// 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 operation =
    CampaignOperation.newBuilder()
        .setUpdate(campaign)
        .setUpdateMask(FieldMasks.allSetFieldsOf(campaign))
        .build();

// 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.
MutateCampaignsResponse response =
    campaignServiceClient.mutateCampaigns(
        customerId.toString(), Collections.singletonList(operation));

下一個範例說明如何正確清除 MaximizeConversions 出價策略中的 target_cpa_micros 欄位。

成功： 下列程式碼會清除 target_cpa_micros。

// Creates a Campaign object with the proper resource name.
Campaign campaign = Campaign.newBuilder()
    .setResourceName(ResourceNames.campaign(customerId, campaignId))
    .build();

// 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 fieldMask = FieldMasks.allSetFieldsOf(campaign)
    .toBuilder()
    .addPaths("maximize_conversions.target_cpa_micros")
    .build();

// Creates an operation to update the campaign with the specified field.
CampaignOperation operation =
    CampaignOperation.newBuilder()
        .setUpdate(campaign)
        .setUpdateMask(fieldMask))
        .build();

請注意，上述「錯誤」範例適用於在 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」範例「不會」更新出價策略來清除 target_cpa 欄位。

重點： 如果您的目標是清除某個欄位，最安全的做法就是將該欄位明確新增至欄位遮罩中。