Overriding bidding strategies
A bid strategy can only be set at the campaign level. So for example, if a
campaign has already been assigned a TARGET_ROAS strategy, setting
TARGET_CPA fields in one of its ad groups will have no effect.
Overriding Target ROAS at the ad group level
The target_roas
field of a standard TARGET_ROAS strategy's
TargetRoas
bidding scheme can be overridden at the ad group level by setting the
target_roas
field of the ad group itself. The other fields of the bidding scheme cannot be
overridden.
To remove an override, unset target_roas of the ad group by sending a
mutate request with an empty field value but still supplying the path in a
field mask (e.g., PHP).
Attempting to override the target_roas of a TargetRoas scheme associated to
a portfolio strategy will result in an error.
You can retrieve the effective target_roas value of an ad group with the
effective_target_roas
field and its source with the effective_target_roas_source
field.
Overriding Target CPA at the ad group level
The target_cpa_micros
field of a TARGET_CPA strategy's
TargetCpa
bidding scheme can be overridden at the ad group level by setting the
target_cpa_micros
field of the ad group itself. The other fields of the bidding scheme cannot be
overridden.
To remove an override, unset target_cpa_micros of the ad group by sending a
mutate request with an empty field value but still supplying the path in a
field mask (e.g., PHP).
You can retrieve the effective value of target_cpa_micros for an ad group from the
effective_target_cpa_micros
field and its source from the effective_target_cpa_source
field.