欄位遮罩

在 Google Ads API 中，欄位遮罩用於提供 API 要求應更新的欄位清單。即使傳送至伺服器，系統也會忽略欄位遮罩中未指定的任何欄位。

FieldMaskUtil 類別

建議使用內建的 FieldMaskUtil 類別產生欄位遮罩，這樣就能從修改過的物件產生欄位遮罩，不必從頭建構。

以下範例說明如何更新廣告活動，並使用 FieldMasks.AllSetFieldsOf 方法產生列舉所有已設定欄位的欄位遮罩。接著，您可以將產生的欄位遮罩直接傳遞至更新呼叫。

// Update campaign by setting its status to paused, and "Search network" to false.
Campaign campaignToUpdate = new Campaign()
{
    ResourceName = ResourceNames.Campaign(customerId, campaignId),
    Status = CampaignStatus.Paused,
    NetworkSettings = new NetworkSettings()
    {
        TargetSearchNetwork = false
    }
};

// Create the operation.
CampaignOperation operation = new CampaignOperation()
{
    Update = campaignToUpdate,
    UpdateMask = FieldMasks.AllSetFieldsOf(campaignToUpdate)
};

// Update the campaign.
MutateCampaignsResponse response = campaignService.MutateCampaigns(
    customerId.ToString(), new CampaignOperation[] { operation });

有時您可能需要使用現有物件，並更新幾個欄位。在這種情況下，您會修改程式碼，改用 FieldMasks.FromChanges 方法。這個方法會產生代表兩個物件差異的欄位遮罩。

Campaign existingCampaign;

// Obtain existingCampaign from elsewhere.
...

// Create a new campaign based off the existing campaign for update.
Campaign campaignToUpdate = new Campaign(existingCampaign);

// Update campaign by setting its status to paused, and "Search network" to
// false.
campaignToUpdate.Status = CampaignStatus.Paused;
campaignToUpdate.NetworkSettings = new NetworkSettings()
{
    TargetSearchNetwork = false
}

// Create the operation.
CampaignOperation operation = new CampaignOperation()
{
    Update = campaignToUpdate,
    UpdateMask = FieldMasks.FromChanges(existingCampaign, campaignToUpdate)
};

如何處理 FieldMaskError.FIELD_HAS_SUBFIELDS 錯誤

在極少數情況下，您可能需要設定欄位，但不必更新該類型的任何子欄位。請參考以下範例：

// Creates a campaign with the proper resource name and an empty
// MaximizeConversions field.
Campaign campaign = new Campaign()
{
    ResourceName = ResourceNames.Campaign(customerId, campaignId),
    MaximizeConversions = new MaximizeConversions()
};

CampaignOperation operation = new CampaignOperation()
{
    Update = campaign,
    UpdateMask = FieldMasks.AllSetFieldsOf(campaign)
};

MutateCampaignsResponse response = campaignService.MutateCampaigns(
    customerId.ToString(), new CampaignOperation[] { operation });

這項 API 呼叫會失敗，並顯示 FieldMaskError.FIELD_HAS_SUBFIELDS 錯誤。 由於 MaximizeConversions 有三個子欄位，Google Ads API 伺服器會預期要求中存在這些欄位的欄位遮罩。不過，由於要求未設定這些欄位，因此 FieldMaskUtil 無法在這種情況下正確產生欄位遮罩。

在這種情況下，您可以手動編輯欄位遮罩，方法如下：

// Creates a Campaign object with the proper resource name.
Campaign campaign = new Campaign()
{
    ResourceName = ResourceNames.Campaign(customerId, campaignId),
};

FieldMask 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.Paths.AddRange(new string[] {
    "maximize_conversions.target_cpa_micros",
});

// Creates an operation to update the campaign with the specified fields.
CampaignOperation operation = new CampaignOperation()
{
    Update = campaign,
    UpdateMask = fieldMask
};

如何清除欄位

Google Ads API 支援清除部分欄位值。如要清除欄位，必須手動設定該欄位的欄位遮罩。將欄位設為預設值 (例如 int64 欄位的零) 不會清除欄位。

以下程式碼範例說明如何清除 MaximizeConversions 出價策略的 target_cpa_micros 欄位。

正確代碼

由於我們在欄位遮罩中設定 maximize_conversions.target_cpa_micros，但未設定 campaign.MaximizeConversions.TargetCpaMicros 欄位，因此下列程式碼會清除 target_cpa_micros 欄位。

// Creates a Campaign object with the proper resource name.
Campaign campaign = new Campaign()
{
    ResourceName = ResourceNames.Campaign(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 fieldMask = FieldMasks.AllSetFieldsOf(campaign);
fieldMask.Paths.AddRange(new string[] {
    "maximize_conversions.target_cpa_micros",
});

// Creates an operation to update the campaign with the specified field.
CampaignOperation operation = new CampaignOperation()
{
    Update = campaign,
    UpdateMask = fieldMask
};

驗證碼有誤

下列程式碼不會清除 target_cpa_micros 欄位，因為我們將這個欄位設為零。FieldMaskUtils 和 Google Ads API 伺服器都會忽略這個值。此外，由於伺服器會忽略該值，因此您可能不會收到錯誤訊息。

// Creates a campaign with the proper resource name and a MaximizeConversions
// object. Attempt to clear the target_cpa_micros field by setting it to 0.
Campaign campaign = new Campaign()
{
    ResourceName = ResourceNames.Campaign(customerId, campaignId),
    MaximizeConversions = new MaximizeConversions()
    {
        TargetCpaMicros = 0
    }
};

// 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 = new CampaignOperation()
{
    Update = campaign,
    UpdateMask = 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.
MutateCampaignsResponse response = campaignService.MutateCampaigns(
    customerId.ToString(), new CampaignOperation[] { operation });