在 Google Ads API 中，更新是使用字段掩码完成的。字段掩码会列出您打算通过更新更改的所有字段，并且系统会忽略字段掩码中未包含的任何指定字段，即使这些字段已发送到服务器也是如此。您可以通过创建 Google\Protobuf\FieldMask、创建一个用您要更改的所有字段的名称填充的数组，然后将该数组分配给字段掩码的路径字段，手动创建字段掩码。
您还可以使用我们的内置字段掩码实用程序 (FieldMasks)，该实用程序会隐藏许多具体详细信息，并允许您通过监控对实体字段所做的更改来自动生成字段掩码。
下面是一个更新广告系列的示例：
$campaign = new Campaign([
'resource_name' => ResourceNames::forCampaign($customerId, $campaignId),
'status' => CampaignStatus::PAUSED
]);
$campaignOperation = new CampaignOperation();
$campaignOperation->setUpdate($campaign);
$campaignOperation->setUpdateMask(FieldMasks::allSetFieldsOf($campaign));
此代码会先创建一个 Campaign 对象，然后使用 ResourceNames 设置其资源名称，以便 API 知道要更新哪个广告系列。status 也设置为 PAUSED。
然后，该代码会创建一个 CampaignOperation 对象，并将之前创建的广告系列设置为该对象。然后，它会使用 FieldMasks::allSetFieldsOf() 使用所有更改后的字段为广告系列创建字段掩码。最后，它会将返回的掩码传递给广告系列操作对象。
请注意，FieldMasks::allSetFieldsOf 是 FieldMasks::compare() 的便捷方法。它会将传递的对象与同一类的空对象进行比较。例如，在前面的代码中，您可以使用 FieldMasks::compare(new
Campaign(), $campaign) 而非 allSetFieldsOf()。
更新消息字段及其子字段
MESSAGE 字段可以有子字段（例如 MaximizeConversions 有三个子字段：target_cpa_micros、cpc_bid_ceiling_micros 和 cpc_bid_floor_micros），也可以没有子字段（例如 ManualCpm）。
未定义子字段的消息字段
更新未使用任何子字段定义的 MESSAGE 字段时，请使用 FieldMasks 生成字段掩码，如前所述。
包含已定义子字段的消息字段
更新使用子字段定义的 MESSAGE 字段时，如果未在该消息上明确设置任何子字段，则必须手动将每个可变 MESSAGE 子字段添加到 FieldMask，这与从头创建字段掩码的上一个示例类似。
一个常见的示例是，更新广告系列的出价策略，但未在新的出价策略中设置任何字段。以下代码演示了如何更新广告系列以使用 MaximizeConversions 出价策略，而无需为出价策略设置任何子字段。
在这种情况下，使用 FieldMasks 的 allSetFieldsOf() 和 compare() 方法无法实现预期目标。
以下代码会生成包含 maximize_conversions 的字段掩码。不过，Google Ads API 不允许这种行为，以免意外清除字段并生成 FieldMaskError.FIELD_HAS_SUBFIELDS 错误。
// 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 will include 'maximize_conversions`,
// which will produce 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 will result in a
// FieldMaskError.FIELD_HAS_SUBFIELDS error because empty MESSAGE fields cannot
// be included in a field mask.
$campaignServiceClient = $googleAdsClient->getCampaignServiceClient();
$response = $campaignServiceClient->mutateCampaigns($customerId, [$campaignOperation]);
以下代码演示了如何正确更新广告系列以使用 MaximizeConversions 出价策略，而无需设置其任何子字段。
// Creates a Campaign object with the proper resource name.
$campaign = new Campaign([
'resource_name' => ResourceNames::forCampaign($customerId, $campaignId)
]);
// Creates a field mask from the existing campaign and adds all of the mutable
// fields (only one in this case) on the MaximizeConversions bidding strategy to
// the field mask. Because this field is included in the field mask but
// excluded from the campaign object, the Google Ads API will set the campaign's
// bidding strategy to a MaximizeConversions object without any of its subfields
// set.
fieldMask = FieldMasks::allSetFieldsOf($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
$fieldMask->setPaths(array_merge(
iterator_to_array($fieldMask->getPaths()->getIterator()),
['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);
清除字段
某些字段可以明确清除。与前面的示例类似，您必须将这些字段明确添加到字段遮罩中。例如，假设您的广告系列使用的是 MaximizeConversions 出价策略，并且 target_cpa_micros 字段的值设为大于 0 的值。
以下代码会运行；不过，系统不会将 maximize_conversions.target_cpa_micros 添加到字段掩码，因此不会对 target_cpa_micros 字段进行任何更改：
// 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' => 0]),
'status' => CampaignStatus::PAUSED
]);
// 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 = new CampaignOperation();
$campaignOperation->setUpdate($campaign);
$campaignOperation->setUpdateMask(FieldMasks::allSetFieldsOf($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.
$campaignServiceClient = $googleAdsClient->getCampaignServiceClient();
$response = $campaignServiceClient->mutateCampaigns($customerId, [$campaignOperation]);
以下代码演示了如何正确清除 MaximizeConversions 出价策略的 target_cpa_micros 字段。
// 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 will
// clear this field from the bidding strategy without impacting any other fields
// on the bidding strategy.
$fieldMask = FieldMasks::allSetFieldsOf($campaign);
$fieldMask->setPaths(array_merge(
iterator_to_array($fieldMask->getPaths()->getIterator()),
['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);
请注意，“错误”代码在 Google Ads API protocol buffers 中定义为 optional 的字段中确实能按预期运行。但是，由于 target_cpa_micros 不是 optional 字段，因此“错误”代码不会更新出价策略以清除 target_cpa 字段。