字段掩码

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在更新后更改的所有字段，并且字段掩码中未包含的任何指定字段都将被忽略，即使发送到服务器也是如此。您可以手动创建字段掩码，方法是创建 Google\Protobuf\FieldMask，使用要更改的所有字段的名称填充数组，然后将其分配给字段掩码的路径字段。

此外，您还可以使用我们的内置字段掩码实用程序 (FieldMasks)，它可以隐藏许多特定细节，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。

以下是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));

此代码首先会创建一个广告系列对象，然后使用 ResourceNames 设置其资源名称，以便 API 知道正在更新哪个广告系列。status 也设置为 PAUSED。

然后，该代码会创建一个 CampaignOperation 对象，并将之前制作的广告系列设置为该对象。然后，它会使用 FieldMasks::allSetFieldsOf() 为所有已更改的字段创建字段掩码。最后，它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() 的一种便捷方法。它会将您传递的对象与同一类的空对象进行比较。例如，在之前的代码中，您可以使用 FieldMasks::compare(new Campaign(), $campaign) 来代替 allSetFieldsOf()。

更新消息字段及其子字段

MESSAGE 字段可以有子字段（例如 MaximizeConversions，它有三个：target_cpa_micros、cpc_bid_ceiling_micros 和 cpc_bid_floor_micros），也可以根本没有子字段（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，如前所述，请使用 FieldMasks 生成字段掩码。

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，如果未为该消息明确设置任何子字段，则必须手动将每个可变的 MESSAGE 子字段添加到 FieldMask，这与上一个从头开始创建字段掩码的示例类似。

一个常见的示例是，在未针对新出价策略设置任何字段的情况下更新广告系列的出价策略。以下代码演示了如何将广告系列更新为使用 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。但是，为防止意外清除字段并产生 FieldMaskError.FIELD_HAS_SUBFIELDS 错误，Google Ads API 不允许这种行为。

// 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，而无需设置广告系列的任何子字段。

// 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);

正在清除字段

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掩码中。例如，假设您有一个使用 MaximizeConversions 出价策略的广告系列，并且 target_cpa_micros 字段的值设置为大于 0 的值。

运行以下代码；不过，由于系统不会将 maximize_conversions.target_cpa_micros 添加到字段掩码中，因此也未对 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”代码确实适用于在 Google Ads API protocol buffers 中定义为 optional 的字段。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。