Hooks ahoy!

Ok, let's get it on with the new hotness in Reactland, React Hooks!
This is a guide covering using the Gatsby custom React hook for
StaticQuery which it is now replacing with useStaticQuery.

If you haven't used Gatsby before StaticQuery is just that, a way to
query data in a Gatsby component (i.e. a react component) or a Gatsby
page where the query input doesn't change. This is a great use case
for data that doesn't change a great deal, like your site metadata.

tl;dr

Here's me trying to even with codesandbox.io whilst I convert some
of the Gatsby default starter that's on codesandbox.io to use the
useSiteMetadata custom hook.

Using codesandbox.io we take a look at implementing a custom react
hook for getting site metadata in Gatsby.

Here's a video:

The StaticQuery component uses the render props pattern, which
means it takes in a function and returns/renders based off of that.

I have detailed this pattern before in a post about using the react
context api, it's a component that you pass a function to, to render
a component.

Think of it like this:

<Component>
 {() => ()}
</Component>

The first parenthesis is the arguments/variables and the second is
what gets rendered, so in the case of the Gatsby StaticQuery you
pass a query with a graphql tag and then the data that comes back
from that is what is used in the render of that component. So you have
your wrapping component that returns and renders a child component,
like this.

<WrappingComponent>
  {args => <ComponentToRender propsForComponent={args.propNeeded} />}
</WrappingComponent>

Here's a cut down version of the StaticQuery component being used in
the Gatsby default starter on codesandbox.io

I've taken out the styling to make it a bit shorter:

const Layout = ({ children }) => (
  <StaticQuery
    query={graphql`
      query SiteTitleQuery {
        site {
          siteMetadata {
            title
          }
        }
      }
    `}
    render={data => (
      <>
        <Header siteTitle={data.site.siteMetadata.title} />
        <div>
          <main>{children}</main>
          <footer />
        </div>
      </>
    )}
  />
);

export default Layout;

The StaticQuery takes in two props, the query and what you want to
render with render, this is where you can destructure the data you
need out of the data prop returned from the query.

I was never really a fan of doing it that way so I adopted a similar
pattern but with the component contained on it's own and then added to
the StaticQuery separately. Like this:

const Layout = ({ children, data }) => (
  <>
    <Header siteTitle={data.site.siteMetadata.title} />
    <div>
      <main>{children}</main>
      <footer />
    </div>
  </>
);

export default props => (
  <StaticQuery
    query={graphql`
      query SiteTitleQuery {
        site {
          siteMetadata {
            title
          }
        }
      }
    `}
    render={data => <Layout data={data} {...props} />}
  />
);

I found this more acceptable because you didn't have to have all the
code bunched into the StaticQuery component.

That all make sense?

Good, now forget about all of that! It's time to use the new
useStaticQuery hotness in Gatsby. ?

Versions:

This guide is being used with the following dependency versions.

  • gatsby: 2.1.31
  • react: 16.8.4
  • react-dom: 16.8.4

You can also check out the example code.


The Gatsby documentation covers the use of it and also how to make
your own custom react hook to use useStaticQuery, here's the one I
use in the video.

useSiteMetadata.js

import { graphql, useStaticQuery } from 'gatsby';

const useSiteMetadata = () => {
  const { site } = useStaticQuery(
    graphql`
      query SITE_METADATA_QUERY {
        site {
          siteMetadata {
            title
            description
            author
          }
        }
      }
    `
  );
  return site.siteMetadata;
};

export default useSiteMetadata;

This can now be implemented in the rest of the code as a function
call:

const { title, description, author } = useSiteMetadata();

Let's implement it!

In the layout component import the useSiteMetadata hook then we
can go about removing the StaticQuery component and destructuring
title from the useSiteMetadata hook.

It should look something like this, I have taken the styling out for
brevity:

import React from 'react';
import PropTypes from 'prop-types';
import useSiteMetadata from './useSiteMetadata';

import Header from './header';
import './layout.css';

const Layout = ({ children }) => {
  const { title } = useSiteMetadata();
  return (
    <>
      <Header siteTitle={title} />
      <div>
        <main>{children}</main>
        <footer>
          © {new Date().getFullYear()}, Built with
          {` `}
          <a href="https://www.gatsbyjs.org">Gatsby</a>
        </footer>
      </div>
    </>
  );
};
Layout.propTypes = {
  children: PropTypes.node.isRequired,
};

export default Layout;

Here's the comparison:

On now to the seo component, same again, remove StaticQuery and
use useSiteMetadata in it's place.

Here's the comparison:

If you want to check out the code the example is available here:
example code

Wrap up!

That's it! Wh have gone from using the awesome StaticQuery render
props pattern used in Gatsby over to the even more awesome
useStaticQuery React hooks, hook.

Thanks for reading ?

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