Create a trigger

Make sure that you have the following:

• A test web server that you can use to send information to Shopify Flow. You can use an existing web server. This web server needs to be able to send POST requests to Shopify's GraphQL Admin API.
• A test app that works with the test web server and can send HTTP requests.
• A development store that has Shopify Flow and the test app installed.
• Your application has access to the read_customers scope. The trigger you will build using this tutorial will be using a customer reference which requires that scope.

To give your Flow action a meaningful name, use the following guidelines:

• Use an object acted on + past tense verb format. For example, Auction bid placed.
• Use sentence case.
• Don't use punctuation.
• Separate words using spaces.

The following steps show how to create a trigger that sends bid information to Shopify Flow when a bid is placed on an auction.

Use the Shopify CLI to generate a new extension:

1. Navigate to your app directory.
2. Run the following command:

1. Select the Flow Trigger as the type of extension.
2. Provide a meaningful name for your extension.
   

After you've followed the prompts, Shopify CLI generates the extension’s file representation in your app's /extensions directory and gives you a success message. You can then go into your app's /extensions directory and start editing your new extension.

The file structure of your extension should look like the following:

To learn more about the extensions file structure, refer to App structure and the documentation for your extension type.

1. Open your Partner Dashboard.
2. Click the app that you want to add your Shopify Flow trigger to.
3. Click Extensions, then click Create or Create extension.
4. Under Flow, click the Flow/Triggers card.
5. Enter an internal extension name for your trigger and click Save.
6. Enter a title and description for the trigger that will be shown to merchants.
7. Copy the GraphQL endpoint that displays under the Trigger description field to a text file. Your app uses this endpoint to send your POST request to Shopify Flow. The endpoint follows the format https://{shop}.myshopify.com/admin/api/latest/graphql.json.
8. In the Request body properties section, click Add property, choose a data type, and create the properties that display in Shopify Flow when a merchant chooses your trigger.

The following procedure requires you to have generated a flow extension using Shopify CLI. In this section you'll use the default trigger template and update it to be a functional extension example.

1. Change description to Trigger for auction bids.
2. On the second [[settings.fields]] field, update:
   • type to number_decimal
   • key to Amount

Running app dev allows changes made to local files to update the draft version of your Flow task extensions. The draft version is only available in your development store.

1. Navigate to your app directory.
2. Run the following command to start using draft versions of your extension(s):

1. Follow the prompts.

After the app dev command has started, you can test the draft version of your trigger in Shopify Flow.

1. In your development store, create a workflow that uses the trigger that you created for your app.

2. Using the Admin GraphQL API, send a flowTriggerReceive mutation with the following arguments:

• The handle of the trigger
• The payload of the trigger containing the fields defined in the extension TOML
  • The size of the payload (keys included) must be under 50 KB. If the size of the properties body exceeds the limit, then Shopify responds to the GraphQL request with a validation error reading Properties size exceeds the limit of 50000 bytes. As a result, workflows with the specified trigger won't start from this request.

The following is an example of a flowTriggerReceive mutation:

Learn how to authenticate your GraphQL Admin API requests.

The following example shows the same mutation sent in a curl request:

Use Shopify CLI to deploy your extensions:

1. Navigate to your app directory.
2. Run the following command to start deploying your extension(s):

1. Follow the prompts.

When you receive confirmation that the deploy was successful, your extensions have been released.

• Familiarize yourself with Shopify Flow and learn about building connectors.
• Connect your app to Shopify Flow so that your app receives data and information when a workflow action runs.
• Learn how to receive lifecycle events from Shopify Flow about the stores that are using your triggers in enabled workflows.
• Learn how to use complex data types in your Shopify Flow trigger.