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Add a synthetic GraphQL API and set up field resolvers

  • Artikkeli

APPLIES TO: All API Management tiers

In API Management, you can add a GraphQL API in one of two models: pass-through to an existing GraphQL endpoint, or import a GraphQL schema and create a synthetic GraphQL API with custom field resolvers. For more information, see the GraphQL overview.

Note

Currently, this feature isn't available in workspaces.

In this article, you'll:

  • Import a GraphQL schema to your API Management instance
  • Set up a resolver for a GraphQL query using an existing HTTP endpoint
  • Test your GraphQL API

If you want to expose an existing GraphQL endpoint as an API, see Import a GraphQL API.

Prerequisites

  • An existing API Management instance. Create one if you haven't already.
  • A valid GraphQL schema file with the .graphql extension.
  • A backend GraphQL endpoint is optional for this scenario.

Go to your API Management instance

  1. In the Azure portal, search for and select API Management services.

    Select API Management services

  2. On the API Management services page, select your API Management instance.

    Select your API Management instance

Add a GraphQL schema

  1. From the side navigation menu, under the APIs section, select APIs.

  2. Under Define a new API, select the GraphQL icon.

    Screenshot of selecting GraphQL icon from list of APIs.

  3. In the dialog box, select Full and complete the required form fields.

    Screenshot of fields for creating a GraphQL API.

    Field Description
    Display name The name by which your GraphQL API will be displayed.
    Name Raw name of the GraphQL API. Automatically populates as you type the display name.
    GraphQL type Select Synthetic GraphQL to import from a GraphQL schema file.
    Fallback GraphQL endpoint Optionally enter a URL with a GraphQL API endpoint name. API Management passes GraphQL queries to this endpoint when a custom resolver isn't set for a field.
    Description Add a description of your API.
    URL scheme Make a selection based on your GraphQL endpoint. Select one of the options that includes a WebSocket scheme (WS or WSS) if your GraphQL API includes the subscription type. Default selection: HTTP(S).
    API URL suffix Add a URL suffix to identify this specific API in this API Management instance. It has to be unique in this API Management instance.
    Base URL Uneditable field displaying your API base URL
    Tags Associate your GraphQL API with new or existing tags.
    Products Associate your GraphQL API with a product to publish it.
    Version this API? Select to apply a versioning scheme to your GraphQL API.

  4. Select Create.

  5. After the API is created, browse or modify the schema on the Design tab.

Configure resolver

Configure a resolver to map a field in the schema to an existing HTTP endpoint. High level steps are provided here. For details, see Configure a GraphQL resolver.

Suppose you imported the following basic GraphQL schema and wanted to set up a resolver for the users query.

type Query {
    users: [User]
}

type User {
    id: String!
    name: String!
}

  1. From the side navigation menu, under the APIs section, select APIs > your GraphQL API.

  2. On the Schema tab, review the schema for a field in an object type where you want to configure a resolver.

    1. Select a field, and then in the left margin, hover the pointer.

    2. Select + Add Resolver

      Screenshot of adding a GraphQL resolver in the portal.

  3. On the Create Resolver page:

    1. Update the Name property if you want to, optionally enter a Description, and confirm or update the Type and Field selections.
    2. In Data source, select HTTP API.

  4. In the Resolver policy editor, update the <http-data-source> element with child elements for your scenario. For example, the following resolver retrieves the users field by making a GET call to an existing HTTP data source.

        <http-data-source>
        <http-request>
            <set-method>GET</set-method>
            <set-url>https://myapi.contoso.com/users</set-url>
        </http-request>
    </http-data-source>

    Screenshot of configuring resolver policy in the portal.

  5. Select Create.

  6. To resolve data for another field in the schema, repeat the preceding steps to create a resolver.

Tip

As you edit a resolver policy, select Run Test to check the output from the data source, which you can validate against the schema. If errors occur, the response includes troubleshooting information.

Test your GraphQL API

  1. Navigate to your API Management instance.

  2. From the side navigation menu, under the APIs section, select APIs.

  3. Under All APIs, select your GraphQL API.

  4. Select the Test tab to access the test console.

  5. Under Headers:

    1. Select the header from the Name drop-down menu.
    2. Enter the value to the Value field.
    3. Add more headers by selecting + Add header.
    4. Delete headers using the trashcan icon.

  6. If you've added a product to your GraphQL API, apply product scope under Apply product scope.

  7. Under Query editor, either:

    1. Select at least one field or subfield from the list in the side menu. The fields and subfields you select appear in the query editor.

    2. Start typing in the query editor to compose a query.

      Screenshot of adding fields to the query editor.

  8. Under Query variables, add variables to reuse the same query or mutation and pass different values.

  9. Select Send.

  10. View the Response.

    Screenshot of viewing the test query response.

  11. Repeat preceding steps to test different payloads.

  12. When testing is complete, exit test console.

Secure your GraphQL API

Secure your GraphQL API by applying both existing authentication and authorization policies and a GraphQL validation policy to protect against GraphQL-specific attacks.

Next steps

Transform and protect a published API