Reverse Mapping

[mbwatson]

Summary

I'm using gatsby-transformer-yaml to manage people and teams. I'm trying to link these so that GraphQL queries for teams return member details, and vice versa. It's a many-to-many situation, and I'm not sure if it's possible or if (more likely) I'm doing something silly

Returning person detail in a query for teams is straight-forward enough by adding. However, the reverse--returning the groups of which people are members--is not quite working for me.

Relevant information

YAML files in the src/data/people directory look like this:

id: username123
name: John Doe
email: johndoe@example.net
title: CEO

and those in src/data/teams look like this

id: awesome
name: Team Awesome
description: Lorem ipsum dolor sit amet, consectetur adipisicing elit. Sint, ipsum!
members:
  - username123
  - otheruser
  - anotherone

Returning detail about people in a query for teams is accomplished by adding

mapping: {
    "TeamsYaml.members": `PeopleYaml`,
},

to my gatsby-config.js, so that the query

{
  allTeamsYaml {
    edges {
      node {
        name
        members {
          id
          name
        }
      }
    }
  }
}

returns

{
  "data": {
    "allTeamsYaml": {
      "edges": [
        {
          "node": {
            "name": "Team Awesome",
            "members": [
              {
                "id": "username123",
                "name": "John Doe"
              },
              {
                "id": "otheruser",
                "name": "Jane Doe"
              },
              {
                "id": "anotherone",
                "name": "Jo Doe"
              }
            ]
          }
        }
      ]
    }
  }
}

as desired.

However, the reverse--returning the groups of which people are members--is not as clear.

I've tried two things:

1. Another Mapping

mapping: {
    "TeamsYaml.members": `PeopleYaml`,
    "PeopleYaml.teams": `TeamsYaml`, // NEW
},

That new addition throws "Cannot query field "teams" on type "PeopleYaml"".

2. Schema Customization

Per https://www.gatsbyjs.org/docs/schema-customization/, I thought this gatsby-node.js

exports.createSchemaCustomization = ({ actions, schema }) => {
    const { createTypes } = actions
    const typeDefs = [`
        type PeopleYaml implements Node {
            teams: [TeamsYaml] @link
        }
    `]
    createTypes(typeDefs)
}

would link the ids of people to those found in the members array in the team YAML file, but this intuition was incorrect here, however I do get something closer to the desired result.

The query

{
  allPeopleYaml {
    edges {
      node {
        name
        teams {
          id
          name
        }
      }
    }
  }
}

returns nulls:

{
  "data": {
    "allPeopleYaml": {
      "edges": [
        {
          "node": {
            "name": "John Doe
            "teams": null
          }
        },
        {
          "node": {
            "name": "Jane Doe"
            "teams": null
          }
        },
        {
          "node": {
            "name": "Jo Doe",
            "teams": null
          }
        }
      ]
    }
  }
}

However, this must be close because in the Explorer, the team fields are all available:

I don't see anything quite like this in the docs or in other existing issues, and any help would be appreciated in getting this reverse mapping working.

File contents (if changed)

gatsby-config.js: Various, as shown above.
package.json: N/A
gatsby-node.js: Various, as shown above.
gatsby-browser.js: N/A
gatsby-ssr.js: N/A

[mbwatson]

Not sure why, but reading the docs today made more sense. Adding the following to the gatsby-node.js links teams and people up nicely as desired--in both directions:

exports.createSchemaCustomization = ({ actions }) => {
    const { createTypes } = actions
    const typeDefs = [
        `type PeopleYaml implements Node {
            teams: [TeamsYaml] @link(by: "members.id", from: "id")
        }`,
     ]
    createTypes(typeDefs)
}

Successful query:

{
	allPeopleYaml {
	  edges {
	    node {
	      id
              name
              teams {
                name
              }
	    }
	  }
	}
}

returns

{
  "data": {
    "allPeopleYaml": {
      "edges": [
        {
          "node": {
            "id": "username123"
            "name": "John Doe
            "teams": [
              {
                "name": "Team Awesome"
              }
            ]
          }
        },
        {
          "node": {
            "id": "otheruser"
            "name": "Jane Doe"
            "teams": [
              {
                "name": "Team Awesome"
              }
            ]
          }
        },
        {
          "node": {
            "id": "anotherone",
            "name": "Jo Doe",
            "teams": [
              {
                "name": "Team Awesome"
              },
              {
                "name": "Team Mediocre
              }
            ]
          }
        }
      ]
    }
  }
}