Contents
To explore Apollo Client further, including queries, mutations, and subscriptions, check out this Apollo Client tutorial on our learning platform. Let’s walk through a simple example of querying GraphQL data using Apollo Client in a React application. You’ve chosen your programming language, database, and Hasura is powering your GraphQL APIs, but what GraphQL client do you use on the front end? One of the most common challenges front-end developers face when starting a new GraphQL project is choosing which GraphQL client to use. While this is handy, from the author query we can only receive an object of type Author, so it doesn’t fulfill the requirement of the Relay specification. The Relay specification says that we need to have a way to query any object via the node query.
Note that you’ll have to restart the app — yarn start — so that Relay compiler can see the new query and generate code for it. See the Relay Compiler setup docs for how to run Relay Compiler in watch mode, to regenerate code as you modify queries. If you’re exploring using GraphQL with Relay, we highly recommend starting with a basic approach and using as few libraries as possible. GraphQL servers can generally be accessed using plain-old HTTP requests, so we can use the fetch API to request some data from our server. For this guide we’ll use GitHub’s GraphQL API as the server, but if you already have a GraphQL server feel free to use that instead.
Step-by-step Guide
When used together, React, GraphQL and Relay form an amazingly strong stack, which I like to call RGR. The RGR stack could blow REST away for good, and push the MVC pattern to the edge of extinction. In a few years, writing MVC applications on REST endpoints might be a thing of the past. The React Native framework has the potential to dominate native application development and leverage shared endpoints with matching Web applications. Writing native applications is hard, React Native is uniquely positioned to change that for good.
For example, by deduplicating identical fields, and precomputing information used at runtime, among other optimizations. Components declare their data dependencies, without worrying about how to fetch them. Relay guarantees that the data each component 1 1 Linux Versus Other Unix-Like Kernels Understanding the Linux Kernel, 3rd Edition needs is fetched and available. Relay keeps management of data-fetching easy, whether your app has tens, hundreds, or thousands of components. And thanks to Relay’s incremental compiler, it keeps your iteration speed fast even as your app grows.
The keys, on the other hand, are exactly what the view is using (as in render the person.name here, and the person.address there). So, if we strip the JSON response from all the values, recursively, what we’re left with is that weird keys-only, data-less JSON; simply a GraphQL string. GraphQL is much more than that, Fastest way to sync two Amazon S3 buckets but we can’t do it justice here, so look for a blog post about it soon. URQL is a good option for bandwidth-constrained applications and teams that require a lightweight, flexible, and easy-to-use GraphQL client approach. Let’s walk through a simple example of querying GraphQL data using URQL in a React application.
Relay uses GraphQL as its query language, but it is not tied to a specific implementation of GraphQL. For more complex cases where updates cannot automatically be merged, Relay provides apis to manually update the local Relay data in response to a mutation. Relay relies on Global Object Identification to provide reliable caching and refetching, and to make it possible to automatically merge updates for objects. With Relay, components and their data dependencies can be quickly modified without modifying other parts of the system. That means you won’t accidentally break other components as you refactor or make changes to your app. Is a senior software developer, Pluralsight author and instructor at CodingHouse.
Query
Relay Modern was released in 2017 as a more straightforward, optimized, and extensible version of the original Relay. Conventions enforced by Relay’s philosophy and architecture allows it to take advantage of the information available about your component. It uses all this information to do a lot of work that developers are required to deal with. By default, Relay takes care of performance as components only re-render when the exact data they use change in the data store.
- To learn more about Relay features such as Fragments, you can refer to the official documentation.
- Relay is a library which connects your React components to your API server.
- Graphcool, a service that provides a production-ready GraphQL API out-of-the-box.
- In that way, the data model and view model can more closely mimic one another and inherently become more manageable as they change and evolve together.
All you need to do is pass a GraphQL query using the graphql template and variables (in case it’s needed). This code creates a mutation named IntroduceShip, which takes a faction ID and a ship name as input. NodeDefinitions returns the Node interface that objects can implement, and returns the node root field to include on the query type. To implement this, it takes a function to resolve an ID to an object, and to determine the type of a given object. This shows adding a ships field to the Faction object that is a connection.
This is because Relay imposes unique fragment names globally so that the compiler can include the definitions in queries sent to the server. This eliminates the chances of errors and takes away the laborious task of referencing the fragments by hand. This allows developers to think only about the component and fragments as one while Relay does all the heavy lifting in the background. Relay minimizes the round-trips to the server by placing the fragments from multiple components into optimized and efficient batches. Let’s create a new folder called components and create a new folder called PodcastItem. Inside this new folder, we are going to create a new file called PodcastItem.
Learn once, write anywhere
Relay is smart enough to assemble these query pieces before executing the query, then re-renders each component with only the data defined by the fragment it contains. A helper function is provided for building mutations with single inputs and client mutation IDs. Helper functions are provided for both building the GraphQL types for nodes and for implementing global IDs around local IDs. Helper functions are provided for both building the GraphQL types for connections and for implementing the resolve method for fields returning those types.
With JSX, you write the views in the familiar and concise way you know , and then transform all JSX into native React before serving it up to the client . JSX is not required to write React applications, but it’s much easier to write, read and maintain. To conclude the above comparison, in other frameworks , the component uses the query as the data source. The implementation details of how the root component executing the query sends data to its descendants is left to us. But Relay takes a different approach of letting the component take care of the data in needs from the data store. This is because we use/access only these two fields in the view for the component.
This proved to be a faster way than anything else in the same domain. There are a couple of features all three clients support, such as caching, queries, mutations, and subscriptions. For example, both Apollo and Relay support normalized caching, while URQL supports document and normalized caching.
In that way, the data model and view model can more closely mimic one another and inherently become more manageable as they change and evolve together. We’ve been doing some pretty cool stuff with JavaScript at my company, and I wanted to write about some of the tools we are using to “up JavaScript’s game”. Obviously JS has been exploding with all the new frameworks and packages to improve its versatility, and in terms of web one of the most popular frameworks is arguably React. In some ways Relay is inspired by Flux, but the mental model is much simpler.
Step 3: When To Use Relay
Relay isn’t derived from the Flux architecture and is used only with GraphQL, which immediately means a big difference from the Redux model. The Store/Reducer/Component interaction we covered in the data tutorial does not really exist with Relay. It Wix Websites Where is my page content when I view the source HTML takes a different approach, and removes a lot of the building work you normally need to do when integrating data. In Relay, fragments are coupled and colocated with components, which allows it to mask the data requirements from the outside world.
The Profile component executes the operation ProfileQuery to a GraphQL server. // Inner component that reads the preloaded query results via `usePreloadedQuery()`. If you’re using your own API we suggest using the get-graphql-schema utility to download your schema into a .graphql file. We see that you have already chosen to receive marketing materials from us. If you wish to change this at any time you may do so by clicking here.
Relay is critical infrastructure in Facebook, there are tens of thousands of components using it. Relay was built in tandem with GraphQL and has full-time staff working to improve it. If you already can render React components, you’re most of the way there. Relay requires a Babel plugin, and to also run the Relay Compiler. GraphQL Connections are considered a best practice for Pagination in GraphQL, and Relay provides first class support for these, as long as your GraphQL server supports them. A fragment is a snippet of GraphQL that is tied to a GraphQL type and which specifies what data to read from an item of that type.
Can Relay Work For Me?
The two projects — Relay and GraphQL — have been in use in production at Facebook for some time, and we’re excited to be bringing them to the world as open source in the future. In the meantime, we wanted to share some additional information about the projects here. Playground which is an interactive environment that allows you to send queries and mutations.
GraphQL Connections are a model for representing lists of data in GraphQL, so that they can easily be paginated in any direction, as well as to be able to encode rich relationship data. To get the most from Relay’s features, you’ll want your GraphQL server to conform to these standard practices. As you can see, URQL is relatively easy to set up and integrate; as with the Apollo and Relay, there are still so many features URQL has to offer. The cache is an instance of InMemoryCache, which allows you to cache query results and configure Apollo Client’s caching strategies.