Create relationship

Create relationships across subgraphs

Finally, we'll create a relationship between entities in our different subgraphs. Our Chinook data source is a music-based dataset that contains a type called Artist. We have a favorite_artist colum on our app_users table.

In /app/app_connector/models/Users.hml, let's add the following relationship:

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---
kind: Relationship
version: v1
definition:
  name: user_to_favorite_artist
  source: Users
  target:
    model:
      subgraph: chinook
      name: Artist
      relationshipType: Object
  mapping:
    - source:
        fieldPath:
          - fieldName: favoriteArtist
      target:
        modelField:
          - fieldName: artistId

Remember, you can use LSP to assist in authoring metadata.

While you can copy and paste the value above, don't forget that LSP is available to assist you when writing your own relationships, permissions, and any other metadata-authoring tasks you'll need to complete.

We can then run the following query and see that — rightly so — everyone's favorite artist is AC/DC 🤘

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query MyQuery {
  app_users {
    name
    user_to_favorite_artist {
      name
    }
  }
}

What just happened?

We created a second subgraph called chinook and added a completely separate data source using the chinook_connector. We then created a relationship across these subgraphs to link disparate tables and make them available via a single query. We can even visualize this using the console's explorer, available in the left-hand navigation.