欄位遮罩

在 Google Ads API 中，更新作業會使用欄位遮罩完成。欄位遮罩會列出您要隨更新變更的所有欄位，而不在欄位遮罩中的指定欄位也會遭到忽略，即使已傳送至伺服器也是如此。

FieldMaskUtil

如要產生欄位遮罩，建議您使用內建的欄位遮罩公用程式，透過修改的物件產生欄位遮罩，而不必從頭開始建構。

以下是更新廣告活動的範例：

// 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));

這個範例首先會建立空白的 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。

這個範例會使用廣告活動的 FieldMasks.allSetFieldsOf() 方法，自動產生列舉所有組合欄位的欄位遮罩，接著，您可以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來更新幾個欄位，可以按照下列方式修改程式碼：

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));

如要從頭建立欄位遮罩，您必須先建立 FieldMask 物件，然後新增要變更為物件的各個欄位名稱。

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)，或者也可以完全沒有子欄位 (例如 ManualCpm)。

未定義子欄位的訊息欄位

更新未在任何子欄位中定義的 MESSAGE 欄位時，請使用 FieldMaskUtil 產生欄位遮罩，如上所述。

含有已定義子欄位的訊息欄位

更新使用子欄位定義的 MESSAGE 欄位時，並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，與上述從頭開始建立欄位遮罩的範例類似。

其中一個常見例子是在不設定新出價策略的任何欄位的情況下，更新廣告活動的出價策略。以下範例說明如何將廣告活動更新為使用 MaximizeConversions 出價策略，而不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。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。

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));

下例示範如何在不設定任何子欄位的情況下，正確更新廣告活動來使用 MaximizeConversions 出價策略。

成效： 下方程式碼已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

部分欄位可以明確清除。與上述範例類似，您必須明確將這些欄位新增至欄位遮罩中。舉例來說，假設您有廣告活動採用 MaximizeConversions 出價策略，且 target_cpa_micros 欄位的值大於 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，因此對 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，但系統不會清除 MaximizeConversions 出價策略的 target_cpa_micros。

// 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」範例對 Google Ads API protocol buffers 中定義為 optional 的欄位有效。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，藉此清除 target_cpa 欄位。

重點： 如果您的目的是清除某個欄位，最安全的方法就是將該欄位明確新增至欄位遮罩中。