> [!CAUTION]
> **Caution:** This documentation is for Google Ads API **v23** . The latest active version is [**v26**](https://developers.google.com/google-ads/api/fields/latest/topic_constant).

[<button style="margin-top:15px">Help me build a query</button>](https://developers.google.com/google-ads/api/fields/v23/topic_constant_query_builder.md.txt) [<button style="margin-top:15px">Proto definition ![GitHub](https://developers.google.com/site-assets/logo-github.svg)</button>](https://github.com/googleapis/googleapis/blob/master/google/ads/googleads/v23/resources/topic_constant.proto)

Use topics to target or exclude placements in the Google Display Network
based on the category into which the placement falls (for example,
"Pets \& Animals/Pets/Dogs").

## topic_constant.id

Field descriptionOutput only. The ID of the topic.
Category`ATTRIBUTE` Data Type`INT64` Type URL`N/A` FilterableTrue SelectableTrue SortableTrue RepeatedFalse Selectable with The following fields/resources can be selected with this field:
[ad_group_criterion](https://developers.google.com/google-ads/api/fields/v23/ad_group_criterion.md.txt) [campaign_criterion](https://developers.google.com/google-ads/api/fields/v23/campaign_criterion.md.txt) [topic_constant](https://developers.google.com/google-ads/api/fields/v23/topic_constant.md.txt)

## topic_constant.path

Field descriptionOutput only. The category to target or exclude. Each subsequent element in
the array describes a more specific sub-category. For example,
{"Pets \& Animals", "Pets", "Dogs"} represents the
"Pets \& Animals/Pets/Dogs" category. List of available topic categories at
<https://developers.google.com/google-ads/api/data/topics>
Category`ATTRIBUTE` Data Type`STRING` Type URL`N/A` FilterableTrue SelectableTrue SortableFalse RepeatedTrue Selectable with The following fields/resources can be selected with this field:
[ad_group_criterion](https://developers.google.com/google-ads/api/fields/v23/ad_group_criterion.md.txt) [campaign_criterion](https://developers.google.com/google-ads/api/fields/v23/campaign_criterion.md.txt) [topic_constant](https://developers.google.com/google-ads/api/fields/v23/topic_constant.md.txt)

## topic_constant.resource_name

Field descriptionOutput only. The resource name of the topic constant.
topic constant resource names have the form:

`topicConstants/{topic_id}`
Category`ATTRIBUTE` Data Type`RESOURCE_NAME` Type URL`N/A` FilterableTrue SelectableTrue SortableFalse RepeatedFalse Selectable with The following fields/resources can be selected with this field:
[ad_group_criterion](https://developers.google.com/google-ads/api/fields/v23/ad_group_criterion.md.txt) [campaign_criterion](https://developers.google.com/google-ads/api/fields/v23/campaign_criterion.md.txt) [topic_constant](https://developers.google.com/google-ads/api/fields/v23/topic_constant.md.txt)

## topic_constant.topic_constant_parent

Field descriptionOutput only. Resource name of parent of the topic constant.
Category`ATTRIBUTE` Data Type`RESOURCE_NAME` Type URL`N/A` FilterableTrue SelectableTrue SortableTrue RepeatedFalse Selectable with The following fields/resources can be selected with this field:
[ad_group_criterion](https://developers.google.com/google-ads/api/fields/v23/ad_group_criterion.md.txt) [campaign_criterion](https://developers.google.com/google-ads/api/fields/v23/campaign_criterion.md.txt) [topic_constant](https://developers.google.com/google-ads/api/fields/v23/topic_constant.md.txt)