In the Google Ads API, updates are done using a field mask. The field mask lists all the fields you intend to change with the update, and any specified fields that are not in the field mask will be ignored, even if sent to the server.
Field mask helper
The recommended way to generate field masks is using the field_mask
helper
function included in the google.api_core
package. It accepts two protobuf
objects and returns a field mask object with a list
field that contains all
of the fields that are different between the two objects.
If None
is passed as the first parameter then the field mask list will just
contain all of the fields on the second protobuf object that are not set to
their default value.
Once constructed the field mask object should be copied onto the operation object that will be send to the server:
Here's an example for updating a campaign:
from google.api_core import protobuf_helpers
from google.ads.googleads.client import GoogleAdsClient
# Retrieve a GoogleAdsClient instance.
client = GoogleAdsClient.load_from_storage()
# Create a new campaign operation.
campaign_operation = client.get_type('CampaignOperation')
# Retrieve a new campaign object from its update field.
campaign = campaign_operation.update
# Mutate the campaign.
campaign.network_settings.target_search_network.value = False
# Create a field mask using the updated campaign.
# The field_mask helper is only compatible with raw protobuf message
# instances, which we can access using the ._pb attribute.
field_mask = protobuf_helpers.field_mask(None, campaign._pb)
# Copy the field_mask onto the operation's update_mask field.
client.copy_from(campaign_operation.update_mask, field_mask)
First, we create an empty CampaignOperation object. Then, we set retrieve an
empty Campaign object from it. We then update that campaign object and create
a new field mask, comparing it to None
, which will generate a field mask list
that only contains the network_settings.target_search_network
field that was
changed.
Here's an example updating an existing campaign. Here we assume the script has
been provided a resource_name
parameter that is a valid resource name for a
campaign and a valid customer_id
:
import proto
from google.api_core import protobuf_helpers
from google.ads.googleads.client import GoogleAdsClient
# Retrieve a GoogleAdsClient instance.
client = GoogleAdsClient.load_from_storage()
# Retrieve an instance of the GoogleAdsService.
googleads_service = client.get_service('GoogleAdsService')
# Search query to retrieve campaign.
query = f"""
SELECT
campaign.network_settings.target_search_network,
campaign.resource_name
FROM campaign
WHERE campaign.resource_name = {resource_name}"""
# Submit a query to retrieve a campaign instance.
response = googleads_service.search_stream(customer_id=customer_id, query=query)
# Iterate over results to retrieve the campaign.
for batch in response:
for row in batch.results:
initial_campaign = row.campaign
# Create a new campaign operation.
campaign_operation = client.get_type('CampaignOperation')
# Set the copied campaign object to a variable for easy reference.
updated_campaign = campaign_operation.update
# Copy the retrieved campaign into the new campaign.
# Here we use the proto.Message.copy_from method because of its simple
# compatibility with the protobuf message instances, which are wrapped
# by the proto-plus library.
proto.Message.copy_from(updated_campaign, initial_campaign)
# Mutate the new campaign.
updated_campaign.network_settings.target_search_network = False
# Create a field mask using the updated campaign.
field_mask = protobuf_helpers.field_mask(
initial_campaign._pb, updated_campaign._pb
)
# Copy the field mask onto the operation's update_mask field.
# Note that the client's copy_from method is designed to work with both native
# messages and messages wrapped by proto-plus, so it works here for the
# update_mask, even though it's an instance of the native message class
# google.protobuf.field_mask_pb2.FieldMask.
client.copy_from(campaign_operation.update_mask, field_mask)
With this strategy, the updated_campaign
will share all the same fields as the
initial_campaign
that was retrieved from the API, namely the resource name.
The generated field mask will tell the API that only the
network_settings.target_search_network
field needs to be changed.