# Create a Sync Tag Invalidate Function Sync Tag Invalidate Functions allow you to run small, single-purpose code whenever your Live Content in Sanity changes. This guide explains how to set up your project, initialize your first blueprint, add a function, and deploy it to Sanity's infrastructure. > [!WARNING] > Experimental feature > This article describes an experimental Sanity feature. The APIs described are subject to change and the documentation may not be completely accurate. > [!WARNING] > Only one sync-tag-invalidate function per dataset allowed > Having multiple `sync-tag-invalidate` functions set up for a single dataset may lead to race conditions or other unexpected results. We limit each dataset to only one deployed `sync-tag-invalidate` function. If you attempt to `blueprints deploy` a blueprint with more than one, you may see an error in the form: `a sync tag invalidation subscription already exists`. > We recommend scoping your `sync-tag-invalidate` function to a specific dataset as shown below, or see the Function `event` [Blueprint configuration reference documentation](https://www.sanity.io/docs/blueprints/blueprint-config) for more configuration options. Prerequisites: - The latest version of `sanity` CLI (`sanity@latest`) is recommended to interact with Blueprints and Functions as shown in this guide. You can always run the latest CLI commands with `npx sanity@latest`. - Node.js v24.x. We highly suggest working on this version as it is the same version that your functions will run when deployed to Sanity. - An existing project and [a role with Deploy Studio permissions](https://www.sanity.io/docs/user-guides/roles) (the `deployStudio` grant). > [!WARNING] > Avoid recursive loops > At this time, Sanity Functions limit recursive loops when using the `@sanity/client` v7.12.0 or later. Use caution when writing functions that may trigger themselves by editing other documents that trigger the function. > Initiating multiple recursive functions may trigger [rate-limiting](https://www.sanity.io/docs/functions/functions-introduction) and may impact your usage limits sooner than expected. If you think you've deployed a recursive function or one that triggers too often, immediately override the deployment with new code, or `destroy` the blueprint. If you’ve previously created a project, you can skip ahead to [Add a Sync Tag Invalidate function](https://www.sanity.io/docs/functions/sync-tag-function-quickstart). ## Set up your project To create a function, you need to initialize a blueprint. Blueprints are templates that describe Sanity resources. In this case, a blueprint describes how your function will respond to updates in your Sanity project. We recommend keeping functions and blueprints a level above your Studio directory. For example, if you have a Marketing Website that uses Sanity, you may have a structure like this: ```text marketing-site/ ├─ studio/ ├─ next-app/ ``` If you initialize the blueprint in the `marketing-site` directory, functions and future resources will live alongside the `studio` and `next-app` directory. > [!TIP] > Functions and Blueprints match your workflow > While the example is our preferred way to organize Blueprints, Functions, and Sanity projects, you can initialize your first blueprint wherever you like. You can even store them inside your Studio directory. ## Create a blueprint Initialize your first blueprint with the `init` command. Replace with your project ID, found in manage or your sanity.config.ts file. **CLI** ```sh npx sanity@latest blueprints init . --type ts --stack-name production --project-id ``` This configures a new blueprint for your project, adds a `sanity.blueprint.ts` [config file](https://www.sanity.io/docs/blueprints/blueprint-config) to the current directory (`.`), and creates a new [stack](https://www.sanity.io/docs/blueprints/blueprints-introduction) named production. Follow the prompt and run your package manager’s install command to add the dependencies. **CLI** ```sh npm install ``` ## Add a Sync Tag Invalidate function Use the `sanity functions add` command to add a new function. You can also run it without any flags for interactive mode. **CLI** ```sh npx sanity@latest functions add --name invalidate-tags --type sync-tag-invalidate --installer npm ``` > [!TIP] > If you’re using a package manager other than npm, set the `--installer` flag to your package manager, like `pnpm` or `yarn`. Run `sanity functions add --help` for more details. After running the command, follow the prompt and add the function declaration to your `sanity.blueprint.ts` configuration. Your file should look like this: **sanity.blueprint.ts** ``` import {defineBlueprint, defineSyncTagInvalidateFunction} from '@sanity/blueprints' export default defineBlueprint({ resources: [ defineSyncTagInvalidateFunction({name: 'invalidate-tags'}), ], }) ``` By default, your new function will receive Live Content sync tag invalidation events for *all* datasets in your project. We recommend you add an `event` to your function definition with a `resource` scoping your function to a particular dataset. **sanity.blueprint.ts** ``` import {defineBlueprint, defineSyncTagInvalidateFunction} from '@sanity/blueprints' export default defineBlueprint({ resources: [ defineSyncTagInvalidateFunction({ name: "invalidate-tags", event: { resource: { type: 'dataset', id: 'myProjectId.myProductionDataset' } } }) ], }) ``` You can see all available options in the [Function section of the Blueprints configuration reference documentation](https://www.sanity.io/docs/blueprints/blueprint-config). If you've followed the directory structure mentioned earlier, you'll see it grow to something like this: ```text marketing-site/ ├─ studio/ ├─ next-app/ ├─ sanity.blueprint.ts ├─ package.json ├─ node_modules/ ├─ functions/ │ ├─ invalidate-tags/ │ │ ├─ index.ts ``` After updating the `sanity.blueprint.ts` file, open `functions/invalidate-tags/index.ts` in your editor. > [!TIP] > The syncTagInvalidateEventHandler function > TypeScript functions can take advantage of the `syncTagInvalidateEventHandler` helper function to provide type support. Examples in this article include both TypeScript and JavaScript function syntax. Every function exports a `handler` from the index file. **functions/invalidate-tags/index.ts (TypeScript)** ``` import { syncTagInvalidateEventHandler } from '@sanity/functions' export const handler = syncTagInvalidateEventHandler(async ({ context, event, done }) => { const time = new Date().toLocaleTimeString() console.log(`Your sync tag invalidate Sanity Function was called at ${time}`) // TODO: add code to do something with the invalidated sync tags provided to you in `event.data.syncTags` try { // notify Sanity that you have completed invalidation const response = await done(event.data.syncTags) console.log('Invalidation complete, Sanity responded with an HTTP', response.status) } catch (e) { console.error('Error invoking Sanity invalidation done endpoint!', e) } }) ``` **functions/invalidate-tags/index.js (JavaScript)** ```javascript import { syncTagInvalidateEventHandler } from '@sanity/functions' export const handler = syncTagInvalidateEventHandler(async ({ context, event, done }) => { const time = new Date().toLocaleTimeString() console.log(`Your sync tag invalidate Sanity Function was called at ${time}`) // TODO: add code to do something with the invalidated sync tags provided to you in `event.data.syncTags` try { // notify Sanity that you have completed invalidation const response = await done(event.data.syncTags) console.log('Invalidation complete, Sanity responded with an HTTP', response.status) } catch (e) { console.error('Error invoking Sanity invalidation done endpoint!', e) } }) ``` The handler receives a `context`, an `event` and a `done` callback. The `event` contains the Live Content sync tags that were invalidated, available at `event.data.syncTags`. You can learn more in the [Function handler reference](https://www.sanity.io/docs/functions/function-wrapper). The `done` callback is an asynchronous method issuing an HTTP request back to Sanity, notifying us that you have completed your invalidation routine. It is a thin wrapper around native node.js `fetch`, returning a fetch `Response`. > [!WARNING] > It is imperative your function notifies Sanity that your invalidation routine is complete by invoking the `done` callback! Failure to do so will yield unexpected Live Content behaviour. It is your responsibility to ensure that this callback completed successfully, so we recommend wrapping the `done` invocation in a `try/catch` and logging any failures. ## Test the function locally You can test functions locally with the functions development playground. Local testing is a great way to experiment without affecting your usage quota. To launch the development playground, run the following: **CLI** ```sh npx sanity functions dev ``` If you run this on the starter function from earlier, you'll see the default output message in the console pane. ![A dark-themed UI for a functions application, showing a JSON payload to invalidate sync tags and a console log of a successful HTTP 204 response.](https://cdn.sanity.io/images/3do82whm/next/11155be59ad797b2aff1d784c7e86e43627164c3-2566x1682.png) Select your new Sync Tag Invalidate function from the list on the left. Note that the Sync Tag Payload panel is populated with a dummy sync tag invalidate event shape that your function can use as a test payload. Click the Run button at the bottom, and you should see the starter Sync Tag Invalidate function template code output its logs to the Console panel: **console** ```text 4/10/2026 9:14:52 AM INFO Your sync tag invalidate Sanity Function was called at 9:14:52 AM 4/10/2026 9:14:52 AM INFO Invalidation complete, Sanity responded with an HTTP 204 ``` > [!TIP] > Development playground > In addition to the `sanity functions dev` command, there's also a more traditional CLI testing interface. > Run the `sanity functions test functionName` command to run the function locally. You can learn more in the [local testing guide](https://www.sanity.io/docs/functions/functions-local-testing) and the [functions CLI reference](https://www.sanity.io/docs/cli-reference/functions). ## Deploy a function Once you're satisfied that the function works as expected, deploy it by deploying the blueprint stack. **CLI** ```sh npx sanity blueprints deploy ``` You can begin using your function when the deployment finishes. Edit a document in a dataset and publish the changes to trigger the function. If you need to change the function, update your code and re-run the deploy command to push the new changes live. ## Check the logs When you tested the function locally, you saw the logs directly in your console. Once deployed, the function and its logs are in the cloud. View the logs with the `functions logs` command. Replace `invalidate-tags` with your function name. **CLI** ```sh npx sanity functions logs invalidate-tags ``` This command outputs the function's logs. Try updating your document, publishing the change, and running the command again to see new logs. ## Destroy a deployed blueprint Sometimes you want to remove a deployed resource so it won't run anymore or affect any future usage quotas. To remove a resources created with a blueprint, you need to either: 1. Remove the definition from the blueprint, and run the `deploy` command again. 2. Destroy the blueprint with the `destroy` command. The `blueprints destroy` command removes, or undeploys*,* the blueprint and all of its resources from Sanity's infrastructure. It does not remove your local files. **CLI** ```sh npx sanity blueprints destroy ``` To remove the resource from the blueprint locally, you can remove it from the `resources` array in the `sanity.blueprint.ts` file, then delete any associated files. ### Redeploying a destroyed blueprint When you run `blueprints destroy`, it's as if you never used `blueprints init` during setup. The only difference is you still have all the files in your directory. To use this blueprint again and redeploy it, you'll need to let Sanity know about it. You can do this by running init again: **CLI** ```sh npx sanity blueprints init ``` This launches an editing interface that lets you reconfigure the blueprint, if needed, and it reconnects the blueprint to Sanity. Now you can add more functions or redeploy. Keep in mind that any environment variables added before destroying the blueprint will not carry over.