Firestore

Firestore and Server-side Google Tag Manager

For those using Server-side Google Tag Manager (sGTM), Firestore can enhance real-time data collection. Here are some use cases:

• Flag undocumented GA4 Events.
• Route undocumented GA4 Events to a different GA4 Property.
• Block undocumented GA4 Events.
• Add an event_group parameter from your documentation to the Event Name in real-time.

This functionality parallels some features found in other event-based analytics tools and third-party documentation solutions.

Syncing GA4 Events & Parameters to Firestore

Google Cloud Firestore is a scalable NoSQL document database ideal for performance-driven applications. Firestore is accessible from Apps Script using the Firestore library.

Firestore’s daily free quota includes 50,000 document Reads, 20,000 document Writes, and 20,000 document Deletes. See Firestore pricing for details.

Syncing GA4 Events & Parameters to Firestore works as follows:

• If an Event Name is missing in Firestore, it’s added with its parameters.
• If an Event Name is in both Firestore and Google Sheet, it’s updated.
• If an Event Name is in Firestore but not in Google Sheet, it’s deleted from Firestore.

Data synchronized with Firestore includes:

Parameter	Description
change_status	added or updated
date_edited	Date when the event_name or parameters were last edited. From the Autofilled Time column.
event_group	Event Group from the Events Sheet
event_name	Event Name from the Events Sheet
event_parameters	Event Parameters from the Events Sheet (Array)
items	Item Parameters from the Events Sheet (Array)
user_properties	User Scoped Parameters from the Events Sheet (Array)

Google Cloud & Firestore Setup

You can either create a new Google Cloud Project for Firestore or add it to your existing sGTM project.

Firestore Setup

1. Select a Cloud Firestore mode:
   • Choose Native Mode
2. Choose a data location
   • Create Database

Create a Google Service Account

To link Firestore with Google Sheets, create a Google Service Account with read/write access:

1. Visit the Google Service Accounts page.
2. Select the Firestore project and click Create Service Account.
3. For the role, select Datastore > Cloud Datastore Owner.
4. Enable “Furnish a new private key” and select JSON as the key type.
5. Click Create to download a .json file with your private key, then save it locally.

Firestore Setup in Google Sheet

1. Go to the Settings Sheet and Firestore settings.
2. Insert the following values from the .json file:
   • Client Email → client_email
   • Project ID → project_id
   • Private Key → private_key
3. First Collection → Suggested name event_data.
   • See Firestore Collections for more info.
4. Sheet Settings → Date Format. Use the dropdown menu.
   • Date comes from Autofilled Time in the Event Sheet.

Firestore settings are stored as Apps Script Script Properties.

Server-side Google Tag Manager Setup

To flag, block, or route undocumented Events in Server-side GTM, a Firestore Lookup Variable is used. This example flags undocumented Events.

Firestore Lookup Variable

To set up, use a Firestore Lookup Variable. For more details, see Enrich Server-side Data With Cloud Firestore by Simo Ahava. Pay particular attention to the Override Project ID section if sGTM and Firestore are in separate projects.

Settings	Value	Description
Lookup type	Document path	“Look up a document by specifying its components (collection, document, subcollection).”
Document path	event_data/{{Event Name}}	If using a different First Collection, replace event_data with that name.
Key Path	event_group	Returns Event Group from Google Sheet.
Override Project ID	your-firestore-project-id	Needed if Firestore is in a different Google Cloud Project.
Convert undefined	not-documented	Flags undocumented Events as not-documented.

Next, edit your GA4 Tag in sGTM. In Parameters to Add / Edit, add event_group as a parameter and your Firestore Lookup Variable as the Value.

In the GA4 Explore report, undocumented Core Web Vital Events are flagged as not_documented.