Feature Request: add build time transformations to useStaticQuery

[khinshankhan]

This is an enhancement to the useStaticQuery hook. According to this https://www.gatsbyjs.com/docs/static-vs-normal-queries/ the queries results are saved into json files. I think it'd be neat and doable to pass in transformations to the hook, eg

  useStaticQuery(
    graphql`
      {
        allMdx {
          edges {
            node {
              id
            }
          }
        }
      }
    `,
    (result) => result.allMdx.edges.map((node) => ({ ...node.node }))
  )

This is a rather simplified example, there are definitely much more complex uses of this, but the benefit is that now these transformations occur at build time rather than during each user request.

Data transformations could make data easier to deal with but the real benefit I see it they can also change the data for different types of access that a raw query may not be able to readily support. Eg if an array there's an array of tags/ categories, developers may want constant lookup for them. A good way would be to use a set or map structure, but graphql doesn't support readily those data types, especially since every field must be specified. An array would be the best type for the query, but a data transformation could make it so ["a", "b"] => {a: true, b: true}, providing the constant lookup.

[violy]

Does useStaticQuery (and <StaticQuery>) should override datas with transformations… I don't think so.
Solving complexity and performance is difficult, and needs trade-offs. But adding layers of functions is probably not the best way to solve it, IMO.

GraphQL is by design made to get optimized and view-based datas.
The problem exposed here, is about GraphQL limitations — in practice, more than in theory.

[khinshankhan]

I think it's misunderstood what the request is. I think it's fine to query the data as is with graphql limitations, but when caching the result, the data could be transformed.

Perhaps I misunderstood the hashed file part, but this link indicated to me that that the results are saved in json files. Perhaps the confusing is the useStaticQuery may be hashing only the query (?) so maybe a different hook needs to be introduced. The new hook may call useStaticQuery under the hood to generate the hashed file for the query, and then the wrapping hook creates a hashed file, separate from the initial query but has the transformation.

[violy]

As mentioned, useStaticQuery results datas is stored (not cached) in plain json files. ok.

You want to transform (and optimize) datas, just after the graphql return, before stored… ok.

I just think that you (in fact, via graphql mutations) should make this transforms (during query run) but it's might be a painful way. here's the difficulty : how to add custom mutation to get most optimized datas, via graphql ? am i right ?

[khinshankhan]

Yes. But I don't particularly care about optimization, I just think allowing us to shape the data is powerful.

Also, I'm still kind of new to graphql but aren't graphql mutations write operations? Does the filesystem + redux create a "database" and graphql mutations would modify the stored files? Is there documentation for that?