Pizza Taxonomies with Sanity and Gatsby

gatsby-node.js

// web/gatsby-node.js
/**
 * Implement Gatsby's Node APIs in this file.
 *
 * See: https://www.gatsbyjs.org/docs/node-apis/
 */

exports.createResolvers = ({ createResolvers }) => {
  const resolvers = {
    SanityTopping: {
      pizzas: {
        type: ["SanityPizza"],
        resolve(source, args, context, info) {
          return context.nodeModel.runQuery({
            type: 'SanityPizza',
            query: {
              filter: {
                toppings: {
                  elemMatch: {
                    id: {
                      eq: source.id
                    }
                  }
                },
              },
            },
          })
        },
      },
    },
  }
  createResolvers(resolvers)
}

schema.js

// studio/schemas/schema.js
import createSchema from 'part:@sanity/base/schema-creator'
import schemaTypes from 'all:part:@sanity/base/schema-type'

export default createSchema({
  name: 'default',
  types: schemaTypes.concat([
    {
      name: 'topping',
      type: 'document',
      title: 'Topping',
      fields: [
        {
          name: 'name',
          type: 'string',
          title: 'Name of Topping'
        },
        {
          name: 'image',
          type: 'image'
        }
      ]
    },
    {
      name: 'pizza',
      type: 'document',
      title: 'Pizza',
      title: 'Name of Pizza',
      fields: [
        {
          name: 'name',
          type: 'string'
        },
        {
          name: 'image',
          type: 'image'
        },
        {
          name: 'toppings',
          type: 'array',
          of: [{
            type: 'reference',
            to: [{type: 'topping'}]
          }]
        }
      ]
    }
  ])
})