React, GraphQL and Relay: A brief introduction

Having the complete flexibility of JavaScript to construct your HTML is liberating. It allows for even more declarative ways to describe dynamic elements, and gives you the super power of modularity. Clean HTML templates matter far less than the performance of your applications. In fact, performance is the primary reason you write HTML using JavaScript in React.We all know that the Document Object Model is the slowest bottleneck in Web development.

  • Data fetching is still a tricky problem, especially as applications become more complicated.
  • Fetching data is hard, dealing with ever-changing data is hard, and performance is hard.
  • You’ll walk up our way in the React component hierarchy and start with the component that’ll render a single link.
  • Relay is a framework for managing and declaratively fetching GraphQL data.
  • Relay builds on top of the Flux pattern and reduces the pattern into one store, handling the cruft previously needed for manually preparing and dispatching actions.

While you work on a Relay project, the Relay compiler will guide you to ensure project-wide consistency and correctness against your GraphQL schema. Global Object Identification consists on providing globally unique ids across your entire schema for every type, built using the Node GraphQL interface. The Example App is a more sophisticated version of what we’ve started building here.

In particular, you’re going to make sure that when other users vote on a link, the link’s vote count updates immediately in the app for all other users without the need to refresh the page. Let’s assume the response will eventually be JSON (it doesn’t need to be, but we’re not scratching that standard yet); a JSON will be a set of keys and values . The keys, on the other hand, are exactly what the view is using (as in render the 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, but we can’t do it justice here, so look for a blog post about it soon.

GraphQL Fundamentals

These posts will culminate in a formal specification of GraphQL to guide implementors across various languages and platforms. We also plan on releasing a reference implementation in the summer, in order to provide a basis for custom deployments and a platform for experimentation. We’re incredibly excited to share this system and work with the open source community to improve it. Many of these attributes are linked to the fact that “REST is intended for long-lived network-based applications that span multiple organizations” according to its inventor. This is not a requirement for APIs that serve a client app built within the same organization. I am also a starter at developing react-native apps and overall using graphql so I have this constant feeling I am missing something not mentioned in the docs which I suppose to already know when working with react.

react graphql relay

By using a properly typed fragment reference as input, the type of the returned data will automatically be Flow-typed without requiring an explicit annotation. At Facebook, we have apps built entirely using Flux, entirely using Relay, or with both. One pattern we see emerging is letting Relay manage the bulk of the data flow for an application, but using Flux stores on the side to handle a subset of application state.

Getting Started

Samer has been writing Rails applications since well before Rails was 1.0, and his favorite frontend framework is React with Flux. In his spare time, Samer helps entrepreneurs validate their startup ideas in the market. Relay uses the Relay Compiler to convert graphql literals into generated files that live alongside your source files. Keep in mind that it is typically considered an anti-pattern to create a single fragment shared across many containers.

react graphql relay

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. Relay requires a bit more up-front setup and tools, in favour of supporting an architecture of isolated components which can scale with your team and app complexity. The result of using the graphql template tag is a GraphQLTaggedNode; a runtime representation of the GraphQL document. Test your GraphQL operations without requiring a connection to a server.

Instead of multiple stores, there is one central store that caches all GraphQL data. Instead of explicit subscriptions, the framework itself can track which data each component requests, and which components should be updated whenever the data change. On a small scale it works well, but when your application grows into multiple models and multiple views, the relations between them get complicated.


It’s been in production use in Facebook’s native apps for several years. Components use fragments to declare their data dependencies, and read data from the Relay store by calling useFragment. Relay is a framework for managing and declaratively fetching GraphQL data. It allows developers to declare what data each component needs via GraphQL, and then aggregate these dependencies and efficiently fetch the data in fewer round trips.

react graphql relay

Any view can read from and write to any model–and with auto-binding, models could write to other views, which in turn will do their own writing. This back-and-forth flow could cause a cascading update, and while it can be avoided with good code, the idea of things going in multiple directions is scary. The solution is in verifiable constraints; having an enforced one-way flow is the smart alternative.

GraphQL Introduction

Invariably fields and additional data are added to REST endpoints as the system requirements change. However, old clients also receive this additional data as well, because the data fetching specification is encoded on the server rather than the client. When this becomes a problem for a system, one solution is to overlay a versioning system onto the REST endpoints.

Relay uses Fragments to declare data requirements for components, and compose data requirements together. 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. If you’re using your own API we suggest using the get-graphql-schema utility to download your schema into a .graphql file. Learn how to send custom headers and other authentication metadata in your queries. Apollo Client’s normalized cache enables you to skip network requests entirely when data is already available locally. Nearly all externally facing REST APIs we know of trend or end up in these non-ideal states, as well as nearly all internal REST APIs.

Instead of REST APIs, have the client ask for exactly what they want , and have the server parse that graph , and respond with exactly what the client requested (no over-fetching, no under-fetching). GraphQL is a great fit for that graph with which the client can ask the server. This may be helpful to reduce redundant fragments when dealing with nested or recursive data within a single Component. Bug in the Relay Compiler that breaks the compilation when there are non-nullable types on the connection types in the schema.

GraphQL schema into your project and make it available to the Relay Compiler. Since we still want to have a bit more custom styling here and there, we also prepared some styles for you that you need to include in the project. Relay was originally created for the React Native sections of the Facebook app, and it has been used adapted and improved by other teams internally and externally. 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.

This means that all fragments must belong to a query when they are rendered, or in other words, they must be “rooted” under some query. Note that a single fragment can still be included by multiple queries, but when rendering a specific instance of a fragment component, it must have been included as part of a specific query request. In other words, a fragment reference is like a pointer to a specific instance of a type that we want to read data from.

Under the hood, it will figure out the most efficient way for your React components to fetch the data that’s required for them to render, based on the data dependencies they declared in their fragments. Fetching complicated object graphs require multiple round trips between the client and server to render single views. For mobile applications operating in variable network conditions, these multiple roundtrips are highly undesirable.

Basically, it’s a framework to manage these operations, and other data mechanics like pagination, filtering and sorting. With Relay, you declare the data required by every component with GraphQL, and Relay figures out when and how to fetch it. Relay also aggregates all the needed queries into efficient network requests and gives the components exactly what they need, when they need it. It also manages write operations with How to Find and Hire a Perfect Game Dev Team in 2022 GraphQL mutations, and offers consistency, optimistic updates and error handling. Relay builds on top of the Flux pattern and reduces the pattern into one store, handling the cruft previously needed for manually preparing and dispatching actions. Instead, they are compiled ahead of time by the Relay Compiler into generated artifacts that live alongside your source code, and which Relay requires to operate at runtime.

On the server, we configure the GraphQL system to map queries to underlying data-fetching code. This configuration layer allows GraphQL to work with arbitrary underlying storage mechanisms. Relay uses GraphQL as its query language, but it is not tied to a specific implementation of GraphQL. Each component specifies its own data dependencies declaratively using a query language called GraphQL. The data is made available to the component via properties on this.props. 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.