feat(gatsby-source-wordpress): Add "path" field to post/page/custom post type entities

[riddla]

Description

Picked up from the documentation change over at #11126, this makes a path field available within the WordPress entities.

Usage example

// [...]
graphql(
  `
    {
      allWordpressPage {
        edges {
          node {
            id
            link
            path
            status
            template
          }
        }
      }
    }
  `
).then(result => {
  if (result.errors) {
    console.log(result.errors)
    reject(result.errors)
  }

  const pageTemplate = path.resolve(`./src/templates/page.js`)

  _.each(result.data.allWordpressPage.edges, edge => {
    createPage({
      path: edge.node.path,
      component: slash(pageTemplate),
      context: {
        id: edge.node.id,
      },
    })
  })
});
// [...]

Related Issues

Related to #11126

[pieh]

This won't handle custom post types. I wonder if we instead could check:

if (e.link && !e.path) 

to check if link is on entity and just sanity check to not override path field if it already exists (someone or some plugin enriching REST endpoint on wordpress side)

[riddla]

Thanks for your feedback. Also the sanity check makes totally sense.

I was conservative regarding the types, as the current Wordpress project I use for testing only has normal pages and posts.
But I should have a deeper look into the example data stemming from the official Gatsby demo wordpress site.

I’ll try it tomorrow :)

[riddla]

@pieh, I added your suggestion.

[ghost]

Thanks for this PR @riddla! Looks good, I will update #11126 when this gets merged.

[sidharthachatterjee]

@riddla Could you please fix the linting issue? Looks great otherwise!

[riddla]

@sidharthachatterjee, we should be good now regarding ESLint.

[riddla]

@pieh, @sidharthachatterjee, we should be good here?

[pieh]

Awesome!

creating paths that matches Wordpress URLs will be much easier now!

[pieh]

Thanks @riddla! 🎉