feat(gatsby): Refine typing on createPages’ graphql function

[ryanditjia]

Description

This PR expands the typing on createPages’ graphql function:

• Accepts TData as generic
• Accepts query: string as first param
• Accepts variables?: Record<string, unknown> as second param
• Returns errors?: any and data?: TData

Below is example code that will be properly typed with this PR merged.

gatsby-node.ts

import { GatsbyNode } from 'gatsby'
import { loadPagesQuery, loadPagesQueryVariables } from './src/types/__generated__/loadPagesQuery'

export const gatsbyNode: GatsbyNode = {
  createPages: async ({ graphql, actions }) => {
    const { createPage } = actions

    const oneThousandPosts = await graphql<loadPagesQuery, loadPagesQueryVariables>(
      `
        query loadPagesQuery($limit: Int!) {
          allMarkdownRemark(limit: $limit) {
            edges {
              node {
                frontmatter {
                  slug
                }
              }
            }
          }
        }
      `,
      { limit: 1000 }, // this will be typed
    )

    if (oneThousandPosts.errors) {
      throw oneThousandPosts.errors
    }

    oneThousandPosts.data.allMarkdownRemark.edges.forEach(edge => {
      createPage({
        path: `/blog/${edge.node.frontmatter.slug}/`,
        ... rest of code
      })
    })
  },
}

[ryanditjia]

errors?: any could use better typing. I couldn’t track the piece of Gatsby code that’s producing this errors object, hence I’m not sure of the correct typing.

An assumption:
errors?: Array<Error>

[freiksenet]

Thank you @ryanditjia!

[sidharthachatterjee]

Published in gatsby@2.12.1