在 Google Ads API 中，更新作業會使用欄位遮罩。欄位遮罩會列出您打算透過更新變更的所有欄位，而任何不在欄位遮罩中的指定欄位都會遭到忽略，即使已傳送至伺服器也不例外。
FieldMaskUtil
產生欄位遮罩的建議方式是使用內建的欄位遮罩公用程式，您可以從修改過的物件產生欄位遮罩，而不需要從頭建構。
以下是更新廣告活動的範例：
// 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 });
首先，我們建立空白的 Campaign 物件。接著，我們會設定資源名稱，讓 API 明確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，自動產生欄位遮罩，列舉所有已設定的欄位。接著，您可以將傳回的遮罩直接傳遞至更新呼叫。
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，您可以修改程式碼，如下所示：
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)
};
如要從頭建立欄位遮罩，請先建立 FieldMask 物件，然後建立陣列，並在其中填入您要變更的所有欄位名稱，最後將陣列內容附加到欄位遮罩的 Path 欄位。
FieldMask fieldMask = new FieldMask();
fieldMask.Paths.AddRange(new string[] { "status", "name" });
更新訊息欄位及其子欄位
MESSAGE 欄位可以有子欄位 (例如 MaximizeConversions，其中有三個：target_cpa_micros、cpc_bid_ceiling_micros 和 cpc_bid_floor_micros)，也可以完全沒有子欄位 (例如 ManualCpm)。
未定義子欄位的訊息欄位
更新未使用任何子欄位定義的 MESSAGE 欄位時，請使用 FieldMasks 產生欄位遮罩，如上所述。
訊息欄位及其定義的子欄位
更新使用子欄位定義的 MESSAGE 欄位時，如果未明確設定該訊息的任何子欄位，您必須手動將每個可變更的 MESSAGE 子欄位新增至 FieldMask，類似於上述範例中從頭建立欄位遮罩。
一個常見的例子是更新廣告活動的出價策略，但未在新的出價策略中設定任何欄位。以下範例說明如何更新廣告活動，以便使用 MaximizeConversions 出價策略，且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 FromChanges() 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 不允許這項行為，以免誤刪欄位並產生 FieldMaskError.FIELD_HAS_SUBFIELDS 錯誤。
// Creates a campaign with the proper resource name and an empty
// MaximizeConversions field.
Campaign campaign = new Campaign()
{
ResourceName = ResourceNames.Campaign(customerId, campaignId),
MaximizeConversions = 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 operation = new CampaignOperation()
{
Update = campaign,
UpdateMask = 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.
MutateCampaignsResponse response = campaignService.MutateCampaigns(
customerId.ToString(), new CampaignOperation[] { 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，但不設定任何子欄位。
// Creates a Campaign object with the proper resource name.
Campaign campaign = new Campaign()
{
ResourceName = ResourceNames.Campaign(customerId, campaignId),
};
// Creates a field mask from the existing campaign and adds all of the fields
// on the MaximizeConversions bidding strategy to the field mask. Because these
// fields are 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 with none of its subfields set.
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
};
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，假設您有一個使用 MaximizeConversions 出價策略的廣告活動，且 target_cpa_micros 欄位已設為大於 0 的值。
以下程式碼會執行，但 maximize_conversions.target_cpa_micros 不會新增至欄位遮罩，因此不會變更 target_cpa_micros 欄位：
// Creates a campaign with the proper resource name and a MaximizeConversions
// object with target_cpa_micros set 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 });
以下範例說明如何正確清除 MaximizeConversions 出價策略的 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
};
請注意，對於在 Google Ads API protocol buffers 中定義為 optional 的欄位，上述「不正確」的範例確實能正常運作。不過，由於 target_cpa_micros 並非 optional 欄位，因此「不正確」範例不會更新出價策略來清除 target_cpa 欄位。