index.md

title	date	author	canonicalLink	publishedAt
Build a Gatsby Blog using the Cosmic source plugin	2018-06-07	Tony Spiro	https://cosmicjs.com/articles/build-a-gatsby-blog-using-the-cosmic-js-source-plugin-jhzwvr45	Cosmic

This article originally appears on the Cosmic website.

In this tutorial, I'm going to show you how to create a simple but blazing fast blog using React, Gatsby, and Cosmic.

TL;DR

Download the GitHub repo.

Check out the demo.

Check out the Cosmic Source Plugin for Gatsby.

Prerequisites

This tutorial requires Node.js and npm. Make sure you already have them installed.

Blog Development

In order to start working on the blog, we first have to set up the environment.

Install Gatsby and Set Up Your Site

First, install the Gatsby CLI:

npm install --global gatsby-cli

Create a new site based on the Gatsby Cosmic starter:

gatsby new gatsby-blog-cosmicjs

Enter in your project's folder:

cd gatsby-blog-cosmicjs

Start the server:

npm run develop

At this point, you can access your Gatsby website by visiting http://localhost:8000.

Install the Cosmic Source Plugin

In a static website, data can be consumed from multiple different sources, for example Markdown files, HTML files, and/or an eternal API (WordPress, Cosmic, etc).

To make consuming data simpler, Gatsby implements a data layer powered by GraphQL. Very exciting stuff!

To connect this data layer with different data providers, you need to integrate a source plugin. Fortunately, there are many source plugins available for common data sources, and an API available to create your own if necessary.

In our case, we are using Cosmic. We need a source plugin to connect data from Cosmic to our Gatsby site. Good news: there's already a source plugin for Cosmic!

Install the source plugin with the following command:

npm install --save gatsby-source-cosmicjs

We're going to use a couple other plugins later, so let's install them here:

npm install --save gatsby-plugin-offline gatsby-source-filesystem

These plugins need some configuration, so let's replace the content of gatsby-config.js with:

module.exports = {
  plugins: [
    `gatsby-plugin-offline`,
    `gatsby-plugin-react-helmet`,
    {
      resolve: `gatsby-source-filesystem`,
      options: {
        path: `${__dirname}/src/pages`,
        name: "pages",
      },
    },
    {
      resolve: "gatsby-source-cosmicjs",
      options: {
        bucketSlug: "gatsby-blog-cosmic-js", // Your Cosmic bucket slug
        objectTypes: ["posts", "settings"], // List of the object types you want to be able to request from Gatsby.
        apiAccess: {
          read_key: "",
        },
      },
    },
  ],
}

A couple of notes on this config:

1. Notice bucketSlug is set to gatsby-blog-cosmic-js. This is a demo Bucket that includes pre-populated content, so when you download the GitHub repo and start the app, it will display demo content right out of the box. You can also import this demo content into your own Cosmic Bucket by going to Your Cosmic Bucket Dashboard > Settings > Apps, then find and install the Gatsby Blog.
2. The API read key is optional and can be set after you login to Cosmic at: Your Cosmic Bucket Dashboard > Settings > Basic Settings

Now restart the server to apply the updates.

Posts List & Settings

First, we want to display the list of posts on the homepage. To do so, add the following content to src/pages/index.js:

import React from "react"
import { Link } from "gatsby"
import get from "lodash/get"
import { Helmet } from "react-helmet"

import Bio from "../components/bio"
import { rhythm } from "../utils/typography"

class BlogIndex extends React.Component {
  render() {
    const siteTitle = get(
      this,
      "props.data.cosmicjsSettings.metadata.site_title"
    )
    const posts = get(this, "props.data.allCosmicjsPosts.edges")
    const author = get(this, "props.data.cosmicjsSettings.metadata")

    return (
      <div>
        <Helmet title={siteTitle} />
        <Bio settings={author} />
        {posts.map(({ node }) => {
          const title = get(node, "title") || node.slug
          return (
            <div key={node.slug}>
              <h3
                style={{
                  marginBottom: rhythm(1 / 4),
                }}
              >
                <Link style={{ boxShadow: "none" }} to={`posts/${node.slug}`}>
                  {title}
                </Link>
              </h3>
              <small>{node.created}</small>
              <p
                dangerouslySetInnerHTML={{ __html: node.metadata.description }}
              />
            </div>
          )
        })}
      </div>
    )
  }
}

export default BlogIndex

export const pageQuery = graphql`
  query IndexQuery {
    allCosmicjsPosts(sort: { fields: [created], order: DESC }, limit: 1000) {
      edges {
        node {
          metadata {
            description
          }
          slug
          title
          created(formatString: "DD MMMM, YYYY")
        }
      }
    }
    cosmicjsSettings(slug: { eq: "general" }) {
      metadata {
        site_title
        author_name
        author_bio
        author_avatar {
          imgix_url
        }
      }
    }
  }
`

Explanation:

At the end of index.js file, we exported pageQuery. These are GraphQL queries which are used to fetch important information about settings and list of posts.

Then, we pass the { data } destructured object as parameter of IndexPage and loop on its allCosmicjsPosts & cosmicjsSettings object to display the data.

Single Post Layout

Till now we have integrated Cosmic source plugin with Gatsby and it's looking like a blog. Now we will work on adding a details page for individual blog posts.

Create the template at src/templates/blog-post.js:

import React from "react"
import { Helmet } from "react-helmet"
import { Link } from "gatsby"
import get from "lodash/get"

import Bio from "../components/bio"
import { rhythm, scale } from "../utils/typography"
import { relative } from "path"

class BlogPostTemplate extends React.Component {
  render() {
    const post = this.props.data.cosmicjsPosts
    const siteTitle = get(
      this.props,
      "data.cosmicjsSettings.metadata.site_title"
    )
    const author = get(this, "props.data.cosmicjsSettings.metadata")
    const { previous, next } = this.props.pathContext

    return (
      <div>
        <style>
          {`
          .post-content {
            text-align: justify;
          }
          .post-hero {
            width: calc(100% + ${rhythm(8)});
            margin-left: ${rhythm(-4)};
            height: ${rhythm(18)};
          }
          @media (max-width: ${rhythm(32)}) {
            .post-hero {
              width: calc(100% + ${rhythm((3 / 4) * 2)});
              margin-left: ${rhythm(-3 / 4)};
              height: ${rhythm(13)};
            }
          }
        `}
        </style>
        <Helmet title={`${post.title} | ${siteTitle}`} />
        <div
          style={{
            marginTop: rhythm(1.4),
          }}
        >
          <Link to="/">← Back to Posts</Link>
        </div>
        <h1
          style={{
            marginTop: rhythm(1),
          }}
        >
          {post.title}
        </h1>
        <p
          style={{
            ...scale(-1 / 5),
            display: "block",
            marginBottom: rhythm(0.6),
            marginTop: rhythm(-0.6),
          }}
        >
          {post.created}
        </p>
        <div
          className="post-hero"
          style={{
            backgroundColor: "#007ACC",
            backgroundImage: `url("${post.metadata.hero.imgix_url}?w=2000")`,
            backgroundSize: "cover",
            backgroundPosition: "center",
            marginBottom: rhythm(0.6),
            position: "relative",
          }}
        />
        <div
          className="post-content"
          dangerouslySetInnerHTML={{ __html: post.content }}
        />
        <hr
          style={{
            marginBottom: rhythm(1),
          }}
        />
        <Bio settings={author} />

        <ul
          style={{
            display: "flex",
            flexWrap: "wrap",
            justifyContent: "space-between",
            listStyle: "none",
            padding: 0,
          }}
        >
          {previous && (
            <li>
              <Link to={previous.slug} rel="prev">
                ← {previous.title}
              </Link>
            </li>
          )}

          {next && (
            <li>
              <Link to={next.slug} rel="next">
                {next.title} →
              </Link>
            </li>
          )}
        </ul>
      </div>
    )
  }
}

export default BlogPostTemplate

export const pageQuery = graphql`
  query BlogPostBySlug($slug: String!) {
    cosmicjsPosts(slug: { eq: $slug }) {
      id
      content
      title
      created(formatString: "MMMM DD, YYYY")
      metadata {
        hero {
          imgix_url
        }
      }
    }
    cosmicjsSettings(slug: { eq: "general" }) {
      metadata {
        site_title
        author_name
        author_bio
        author_avatar {
          imgix_url
        }
      }
    }
  }
`

That looks fine, but at this point, Gatsby does not know when this template should be displayed. Each post needs a specific URL. So, we are going to inform Gatsby about the new URLs we need using the createPages API.

Path: gatsby-node.js

const path = require("path")

exports.createPages = async ({ graphql, actions, reporter }) => {
  const { createPage } = actions
  const indexPage = path.resolve("./src/pages/index.js")
  createPage({
    path: `posts`,
    component: indexPage,
  })

  const blogPost = path.resolve("./src/templates/blog-post.js")

  const result = await graphql(
    `
      {
        allCosmicjsPosts(
          sort: { fields: [created], order: DESC }
          limit: 1000
        ) {
          edges {
            node {
              slug
              title
            }
          }
        }
      }
    `
  )

  if (result.errors) {
    reporter.panicOnBuild(`Error while running GraphQL query.`)
    return
  }

  // Create blog posts pages.
  const posts = result.data.allCosmicjsPosts.edges

  posts.forEach((post, index) => {
    const next = index === posts.length - 1 ? null : posts[index + 1].node
    const previous = index === 0 ? null : posts[index - 1].node

    createPage({
      path: `posts/${post.node.slug}`,
      component: blogPost,
      context: {
        slug: post.node.slug,
        previous,
        next,
      },
    })
  })
}

Restart the Gatsby server, then visit the detail page by clicking on URLs displayed on the homepage.

Extra Stuff!

In addition to the code covered in this tutorial, we also implemented src/components/bio.js to display author information & src/layouts/index.js to create a generic layout for the blog.

The source code for this tutorial is available on GitHub. To see it live, clone the repository, and run (cd gatsby-blog-cosmicjs && npm i && npm run develop) or check out the demo on Netlify.

The static website generated by Gatsby can easily be published on services like Netlify, S3/CloudFront, GitHub Pages, GitLab Pages, Heroku, etc.

Conclusion

Congrats! You’ve successfully built a super fast and easy-to-maintain blog! Feel free to continue this project to discover both Gatsby and Cosmic advantages.