React Hooks with Apollo GraphQL

published Dec 9, 2018

With React 16.7 we were introduced to hooks. A way to allow things like state, refs, and lifecycle functions to live inside functional components, functionality once only available in class based components.

The great thing about hooks though is that libraries can take the base hooks of useState, useEffect, useRef, and build on top of them to have custom hooks which encapsulate more complicated logic.

In this article we'll look at how to use hooks with the Apollo GraphQL library. The final version of the app we're working with is here.

Setup

First things first you'll need to make sure you're on a version of React that supports hooks... anything 16.7.0 (including alpha versions) should be good!

Now we can install the library which provides the ability to use hooks with Apollo with the command yarn add react-apollo-hooks.

Lastly, we need to make sure we have a new provider in-place, allowing us to use hooks anywhere in our application. Your top level component should end up with something along the lines of:

// other imports
import { ApolloProvider } from "react-apollo";
import { ApolloProvider as ApolloProviderHooks } from "react-apollo-hooks";
import apolloClient from "./apolloClient";

// inside render function:
<ApolloProvider client={apolloClient}>
<ApolloProviderHooks client={apolloClient}>
{/* everything else inside*/}
</ApolloProviderHooks>
</ApolloProvider>;

Queries with useQuery

With everything installed it's time to convert our code using the Query component to use the useQuery hook.

Before with Query

The typical way you've used the Query component up to this point is to have it inside of the JSX you're returning from the component. Inside of the Query component you'll have a render prop function as its child, receiving {data, loading} and any of the other variables you might require as returned from the query's result.

// other imports
import { Query } from "react-apollo";

default class StarredRepos extends React.Component {
render() {
return (
<div>
<Query query={STARRED_REPOS_QUERY} variables={{ numRepos: 25 }}>
{({ data, loading }) => {
if (loading) {
return <span>Loading...</span>;
}

return data.viewer.starredRepositories.nodes.map(node => (
<Repository data={node} key={node.id} />
));
}}
</Query>
</div>
);
}
}

After with useQuery

For the conversion to use hooks, you'll need to ensure your component is a functional component. Now, instead of having Query nested inside of your JSX, you can have it at the top of the function. Here you can pass in the query along with any variables or other options needed. I'll explain what suspend: false means below the code example. As a result you get {data, loading} and any other variables typically returned from the query result.

// other imports
import { useQuery } from "react-apollo-hooks";

default function StarredRepos() {
const { data, loading } = useQuery(STARRED_REPOS_QUERY, {
variables: { numRepos: 25 },
suspend: false
});

if (loading) {
return <span>Loading...</span>;
}

return data.viewer.starredRepositories.nodes.map(node => (
<Repository data={node} key={node.id} />
));
}

useQuery with Suspense

Above I mentioned we'll talk about what the suspend: false option was. By default the useQuery function relies on Suspense to handle what to display when in a loading state. For this to work, you'll need to have a component higher up the tree wrapping the code in a Suspense component, providing it with a fallback prop of what to display while the query is still loading.

// In App.jsx
// other imports
import React, { Suspense } from "react";

// inside render function
<Suspense fallback={<span>Suspense loading...</span>}>
<StarredRepos />
</Suspense>;

By having this code in place, we can make our StarredRepos component even simpler, relying on Suspense to show the fallback when the query is loading.

// other imports
import { useQuery } from "react-apollo-hooks";

default function StarredRepos() {
const { data } = useQuery(STARRED_REPOS_QUERY, {
variables: { numRepos: 25 }
});

return data.viewer.starredRepositories.nodes.map(node => (
<Repository data={node} key={node.id} />
));
}

Mutations with useMutation

The useMutation hook functions similarly to the useQuery hook we looked at above. A typical mutation with the Mutation component looks like this:

// other imports
import { Mutation } from "apollo-react";

const SET_LANGUAGE_FILTER = gql`
mutation SetLanguageFilter($language: String) {
setLanguageFilter(language: $language) @client
}
`;

default function Filters() {
return (
<Mutation mutation={SET_LANGUAGE_FILTER}>
{setLanguageFilter => (
<button
onClick={() => {
setLanguageFilter({ variables: { language: "Ruby" } });
}}
>
Ruby
</button>
)}
</Mutation>
);
}

Let's see what the same code would look like using the useMutation hook.

// other imports
import { Mutation } from "apollo-react";

const SET_LANGUAGE_FILTER = gql`
mutation SetLanguageFilter($language: String) {
setLanguageFilter(language: $language) @client
}
`;

default function Filters() {
const setLanguageFilter = useMutation(SET_LANGUAGE_FILTER);

return (
<button
onClick={() => {
setLanguageFilter({ variables: { language: "Ruby" } });
}}
>
Ruby
</button>
);
}

Difference more pronounced when combined

If you have a component which includes both a Mutation and a Query, the result is even more improved because your code looks less like a Christmas tree (example below).

export default function MyComponent() {
return (
<Mutation mutation={MY_MUTATION}>
{myMutation => (
<Query query={MY_QUERY}>
{({ data }) => (
<button
onClick={() => {
myMutation();
}}
>
{data}
</button>
)}
</Query>
)}
</Mutation>
);
}

When the code above is converted to use hooks it becomes a lot easier to read and reason about. The reason for this is because it's flatter, flows from top to bottom, has separated the data logic from the display logic, and ends up being 5 lines less code in the process!

export default function MyComponent() {
const myMutation = useMutation(MY_MUTATION);
const { data } = useQuery(MY_QUERY);

return (
<button
onClick={() => {
myMutation();
}}
>
{data}
</button>
);
}

Conclusion

In all of the the examples above, the code using hooks comes out looking quite a bit cleaner and easier to wrap your head around than the corresponding examples using the Query and Mutation examples. Try using hooks today and see what you think for yourself!