Gatsby theme blog core

[ChristopherBiscardi]

cc/ @NickyMeuleman

Create gatsby-theme-blog-core

This PR creates a parent theme called gatsby-theme-blog-core which is then used as the parent of gatsby-theme-blog.

gatsby-theme-blog-core

The core theme is a theme meant to encourage re-use of the BlogPost core type to build an ecosystem of compatible blog themes on the same base. The BlogPost interface itself enables people to create backing implementations from any node type in the Gatsby ecosystem, leading us one step further down the path to supporting any CMS. The core theme implements this approach for Mdx nodes sourced from the included filesystem source. More info on the ability to source from multiple node types here.

The theme:

• contains all data structures, sources, and processing
• Contains page creation (createPage calls) with templates that render JSON.stringify(props.data, null, 2)

gatsby-theme-blog

gatsby-theme-blog becomes effectively a collection of components used to render a Gatsby site. This allows anyone to do the same by shadowing two components from the core theme (src/gatsby-theme-blog-core/components/posts.js and src/gatsby-theme-blog-core/components/post.js).

• removed gatsby-node.js as it no longer does anything
• shadowed gatsby-theme-blog-core components to implement theme-ui, etc based layouts

[NickyMeuleman]

Thanks for tagging me to this PR!

I read your comment on pagination in the other thread.
How do you feel about it being an option to include (default is no pagination)?

I did this in my themejam submission, the relevant section in gatsby-node:
https://github.com/NickyMeuleman/gatsby-theme-nicky-blog/blob/d37c8f35c2dbde1365edcce001e926fc3005ccdb/theme/gatsby-node.js#L188-L224

---

Also on that site, I'm transforming the tags array in the frontmatter of a post to an array of objects in graphQL that have this form { name: String, slug: String }. That worked surprisingly well, ability to query both fields.
Unfortunately, for the page that groups all tags. I couldn't figure out how to query a group of them AND access both fields in graphQL:

query MyQuery {
  allBlogPost {
    group(field: tags) {
      fieldValue {
        name
        slug
      }
    }
  }
}

errors out, as the fieldValue alone returns a string: "object Object"
(as a dirty fix, I resorted to passing that info via the pageContext, instead of querying for the data in a page/component)

[ChristopherBiscardi]

@NickyMeuleman

Thanks for tagging me to this PR!

🎉

I read your comment on pagination in the other thread.
How do you feel about it being an option to include (default is no pagination)?

I don't like including it by default. I think we should include it as an extension to the data model in some way. I don't know exactly what that looks like yet, but it means we won't have to support n* features in -core if we can pull off "data extension" like this.

(personally I don't think pagination is useful, especially for the amount of content the "average" blogger puts out and the purpose of having a page listing. Why make it harder for people to CMD+F through your list of posts? ...but this is a different discussion than the data one above).

Unfortunately, for the page that groups all tags. I couldn't figure out how to query a group of them AND access both fields in graphQL:

I generally avoid nested fields unless it's an additional type. I think in -core we'll solve this problem using a Tag extension that can be used across other interfaces (BlogPost, Note, etc). Then you'd be able to do this if you wanted a list of all tags and such:

query MyQuery {
  allTag {
    name
    slug
  }
}

[ChristopherBiscardi]

Implemented BlogPost as an Interface in the last commit. Nothing had to change in gatsby-theme-blog

[KyleAMathews]

👍 to post-query.js

[stefanprobst]

Duplicated body field

Suggested change

body: String!

[stefanprobst]

Suggested change

	date: Date! @dateformat(formatString: "DD-MM-YYYY")
	date: Date! @dateformat

Or, if we want a default format string, we should have it on MdxBlogPost as well

[jxnblk]

Should this be referencing gatsby-starter-blog-theme-core in this README?

Suggested change

	gatsby new my-themed-blog https://github.com/gatsbyjs/gatsby-starter-blog-theme
	gatsby new my-themed-blog https://github.com/gatsbyjs/gatsby-starter-blog-theme-core

[ChristopherBiscardi]

Rebased and made all suggested changes. This should be good to go.

[KyleAMathews]

Looking great!

[KyleAMathews]

title, date, excerpt aren't used anymore right?

[johno]

🏗 😻