Template for building deeply nested FQL queries for FaunaDB

nested-fql-template.js

const baseQuery = q.Paginate(q.Match(q.Index(indexName), terms));
// or
// const baseQuery = q.Paginate(q.Collection(collectionName))

const expandedQuery = q.Map(baseQuery, (ref) =>
  q.Let(
    {
      instance: q.Get(q.Var('ref'))
    },
    {
      // easy stuff
      _id: q.Select(['id'], q.Var('ref')),
      _ts: q.Select(['ts'], q.Var('instance')),
      scalarField: q.Select(['data', 'scalarField'], q.Var('instance'), null),
      scalarArray: q.Select(['data', 'scalarArray'], q.Var('instance'), []),

      // embedded fields
      embeddedField: q.Select(
        ['data', 'embeddedField'],
        q.Var('instance'),
        null
      ),
      /* or */
      selectedEmbeddedField: q.Let(
        {
          embeddedField: q.Select(
            ['data', 'embeddedField'],
            q.Var('instance'),
            null
          )
        },
        q.If(q.Equals([q.Var('embeddedField'), null]), null, {
          a: q.Select(['a'], q.Var('embeddedField'), null),
          b: q.Select(['b'], q.Var('embeddedField'), null)
        })
      ),

      // one-to-one w/ reference in this collection
      referenceField: q.Let(
        {
          ref: q.Select(['data', 'referenceField'], q.Var('instance'), null),
          instance: q.Get(q.Var('ref'))
        },
        {
          /* repeat above recursively */
          /* `ref` and `instance` variables are scoped! */
        }
      ),

      // multiple references in this collection
      referenceArray: q.Map(
        q.Select(['data', 'referenceArray'], q.Var('instance'), []),
        (ref) =>
          q.Let(
            {
              instance: q.Get(q.Var('ref'))
            },
            {
              /* repeat above recursively */
              /* `ref` and `instance` variables are scoped! */
            }
          )
      ),

      // one-to-one with reference in other collection
      indexByRef: q.Let(
        {
          page: Paginate(Match(Index('thing2ByThing1'), q.Var('instance'))),
          data: q.Select('data', q.Var('page')),
          ref: q.Take(1, q.Var('data')),
          instance: q.Get(q.Var('ref'))
        },
        {
          /* repeat above recursively */
          /* `ref` and `instance` variables are scoped! */
        }
      ),

      // one-to-many with reference in other collection
      indexByRef: q.Map(
        q.Paginate(Match(Index('thing2sByThing1'), q.Var('instance'))),
        (ref) =>
          q.Let(
            {
              instance: q.Get(q.Var('ref'))
            },
            {
              /* repeat above recursively */
              /* `ref` and `instance` variables are scoped! */
            }
          )
      ),

      // many-to-many with link table
      indexByRef: q.Map(
        q.Paginate(Match(Index('thing2sByThing1s'), q.Var('instance'))),
        (linkRef) =>
          q.Let(
            {
              link: q.Get(q.Var('linkRef')),
              ref: q.Select(['data', 'thing2'], q.Var('link')),
              instance: q.Get(q.Var('ref'))
            },
            {
              /* repeat above recursively */
              /* `ref` and `instance` variables are scoped! */
            }
          )
      )
    }
  )
);