Automatic support for many-to-many fields through linked node creation in source plugins

So in the last few days I tried to get only Wordpress posts with a passed variable (id of a category)… I am creating category sites in gatsby-node, which uses my category template.

Is there a simple way in GraphQL to filter after categories with this plugin? Categories is the only node which is not selectable in the GraphiQL Editor…

{
  allWordpressPost(filter: {categories is not here}) {
    edges {
      node {
        id
        categories {
          id
        }
      }
    }
  }
}

[KyleAMathews]

Would love to help someone through a PR to add support for filtering on linked nodes 👍

[calcsam]

This is a limitation of how you can query many-to-many fields in GraphQL with Gatsby – we don’t automatically create two-way Connection links between nodes pulled in by some plugins, which is required to do the type of querying you discuss.

This would be a bit of a complicated PR and should happen in gatsby core rather than the Wordpress source plugin; feel free to dive in if you’d like.

https://github.com/gatsbyjs/gatsby/blob/57f7b0d372a7461f019ce86a9003371d45204f3b/packages/gatsby/src/schema/build-node-connections.js