add typeName option to gatsby-transformer-json

[eLod]

see #7670

[pieh]

Please check inline comments - they are not required, but would make code more maintainable.

Main blocker would be missing documentation of typeName config option

[pieh]

could You convert input data to something that's more readable - for example:

const fixtures = [
  {
    typeName: null,
    exptectedNodeTypes: [`NodeNameJson`, `NodeNameJson`],
  }, {
  // rest of input data
]

[pieh]

Could this be changed to use more of jest api instead of relying on jest internals:

expect(createNode).toBeCalledWith(
  expect.objectContaining({
    internal: expect.objectContaining({
      type: expectedOne
    })
  })
)

[eLod]

sure i can do the code changes. about the documentation: do you have any templates/guides/anything i can follow?

[pieh]

We usually document that in package README files - for example contentful plugin have "configuration option" section https://github.com/gatsbyjs/gatsby/tree/master/packages/gatsby-source-contentful#configuration-options - it might be fine to add section like that and probably additional section below with examples of fixed typeName and function typeName

[eLod]

@pieh added some commits, pls check the docs part, i'm not a native english speaker, let me know if you need anything else

documentation was added

[pieh]

I'm definitely not native speaker too :)

I started to think if maybe we could change signature of typeName function a little bit - so we pass object instead of 3 args:

-getType(node, obj, true)
+getType({node, obj, isArray:true})

reason for that: if people will want to add more args in future to this function this might become quite long list of args and using that start looking like that in gatsby-config:

      resolve: `gatsby-transformer-json`,
      options: {
        typeName: ((node, object, iDontUseThat, iDontUseThat2, iDontUseThat3, thisIsArgICareAbout) => thisIsArgICareAbout),
      },

with object they could destructure params they want - what ya think?

[eLod]

@pieh agreed, pushed

[pieh]

Thanks @eLod!

[theredwillow]

I thought it would do this. But it doesn't seem to do anything at all. What is this?

I was hoping to use this functionality to override the gatsby extracting-queries error that occurs with improperly named files.

Missing onError handler for invocation 'extracting-queries', error was 'Error: Names must match /^[_a-zA-Z][_a-zA-Z0-9]*$/ but "" does not.

Names must match /^[_a-zA-Z][_a-zA-Z0-9]*$/ but "" does not.'. Stacktrace was 'Error: Names must match /^[_a-zA-Z][_a-zA-Z0-9]*$/ but "" does not.

Names must match /^[_a-zA-Z][_a-zA-Z0-9]*$/ but "" does not.
    at assertValidSchema (/.../node_modules/graphql/type/validate.js:71:11)
    at validate (/.../node_modules/graphql/validation/validate.js:54:35)
    at extractOperations (/.../node_modules/gatsby/src/query/query-compiler.js:212:20)
    at processQueries (/.../node_modules/gatsby/src/query/query-compiler.js:171:45)
    at compile (/.../node_modules/gatsby/src/query/query-compiler.js:82:19)'

I have files that I download from another application regularly. I suppose I could create a npm script to convert the filenames before the build, but that seems to kinda defeat the purpose of using Gatsby as the generator. Is there a way to do this?