Reason-apollo

React-apollo with Reason

Install and setup

Install

yarn add reason-apollo

# Add graphql_ppx
yarn add --dev graphql_ppx

# Add JS dependencies
yarn add react-apollo apollo-client apollo-cache-inmemory apollo-link apollo-link-context apollo-link-error apollo-link-http graphql graphql-tag apollo-link-ws apollo-upload-client subscriptions-transport-ws

bsconfig

Add reason-apollo to your bs-dependencies and graphql_ppx/ppx to your ppx_flags

bsconfig.json

"bs-dependencies": [
  "reason-react",
  "reason-apollo"
],
"ppx-flags": [
    "graphql_ppx/ppx"
]

Send introspection query

This will generate a graphql_schema.json which will be used to safely type your GraphQL queries/mutations.

yarn send-introspection-query http://my-api.example.com/api

Why reason-apollo?

Watch its usage in this video:

Usage

Create the Apollo Client

Client.re

/* Create an InMemoryCache */
let inMemoryCache = ApolloInMemoryCache.createInMemoryCache();

/* Create an HTTP Link */
let httpLink =
  ApolloLinks.createHttpLink(~uri="http://localhost:3010/graphql", ());

let instance =
  ReasonApollo.createApolloClient(~link=httpLink, ~cache=inMemoryCache, ());

ApolloProvider

Index.re

/*
   Enhance your application with the `ReasonApollo.Provider`
   passing it your client instance
 */
ReactDOMRe.renderToElementWithId(
  <ReasonApollo.Provider client=Client.instance>
    <App />
  </ReasonApollo.Provider>,
  "index",
);

Query

MyComponent.re

/* Create a GraphQL Query by using the graphql_ppx */
module GetPokemon = [%graphql
  {|
  query getPokemon($name: String!){
      pokemon(name: $name) {
          name
      }
  }
|}
];

module GetPokemonQuery = ReasonApollo.CreateQuery(GetPokemon);

let make = _children => {
  /* ... */,
  render: _ => {
    let pokemonQuery = GetPokemon.make(~name="Pikachu", ());
    <GetPokemonQuery variables=pokemonQuery##variables>
      ...{
           ({result}) =>
             switch (result) {
             | Loading => <div> {ReasonReact.string("Loading")} </div>
             | Error(error) =>
               <div> {ReasonReact.string(error##message)} </div>
             | Data(response) =>
               <div> {ReasonReact.string(response##pokemon##name)} </div>
             }
         }
    </GetPokemonQuery>;
  },
};

Mutation

MyMutation.re

module AddPokemon = [%graphql
  {|
  mutation addPokemon($name: String!) {
      addPokemon(name: $name) {
          name
      }
  }
|}
];

module AddPokemonMutation = ReasonApollo.CreateMutation(AddPokemon);

let make = _children => {
  /* ... */,
  render: _ =>
    <AddPokemonMutation>
      ...{
           (mutation /* Mutation to call */, _) => {
             /* Result of your mutation */

             let newPokemon = AddPokemon.make(~name="Bob", ());
             <div>
               <button
                 onClick={
                   _mouseEvent =>
                     mutation(
                       ~variables=newPokemon##variables,
                       ~refetchQueries=[|"getAllPokemons"|],
                       (),
                     )
                     |> ignore
                 }>
                 {ReasonReact.string("Add Pokemon")}
               </button>
             </div>;
           }
         }
    </AddPokemonMutation>,
};

ApolloConsumer

If you simply want to have access to the ApolloClient, you can use the ApolloConsumer

<ApolloConsumer>
  ...{apolloClient => {/* We have access to the client! */}}
</ApolloConsumer>;

Tips and Tricks

Use @bsRecord on response object

The @bsRecord modifier is an extension of the graphql syntax for BuckleScipt/ReasonML. It allows you to convert a reason object to a reason record and reap the benefits of pattern matching. For example, let's say I have a nested object of options. I would have to do something like this:

switch response##object {
| Some(object) => {
  switch object##nestedValue {
  | Some(nestedValue) => nestedValue
  | None => ""
  }
}
| None => ""
}

Kind of funky, huh? Let's modify the response and convert it to a reason record.

type object = {
  nestedValue: option(string)
}


module GetObject = [%graphql {|
  object @bsRecord {
    nestedValue
  }
 |}
];

This time we can pattern match more precisely.

switch response##object {
| Some({ nestedValue: Some(value) }) => value
| Some({ nestedValue: None }) => ""
| None => ""
}

Use an alias for irregular field names

You might find yourself consuming an API with field names like Field. Currently, reason object field names are required to be camel case. Therefore if you have a request like this:

{
  Object {
    id
    title
  }
}

You will attempt to access the response object but it will throw an error:

response##Object; /* Does not work :( */

Instead, use an alias to modify the response:

{
  object: Object {
    id
    title
  }
}

Then you can access the object like this:

response##object

Generic Error and Loading components

You can create a generic error and Loading component and compose them like this example:

module QueryView = {
  let component = ReasonReact.statelessComponent(__MODULE__);

  let make =
      (
        ~result: ReasonApolloTypes.queryResponse('a),
        ~accessData: 'a => option('b),
        ~render: ('b, 'c) => ReasonReact.reactElement,
        ~onLoadMore: ('b, 'unit) => unit=(_, ()) => (),
        _children,
      ) => {
    ...component,
    render: _self =>
      switch (result) {
      | Error(error) => <Error />
      | Loading => ReasonReact.null
      | Data(response) =>
        switch (accessData(response)) {
        | Some(data) => render(data, onLoadMore(data))
        | _ => <Error error="" />
        }
      },
  };
};

FAQ

I've added the schema file, but my build fails saying it couldn't be found?

In some cases, it seems like there are some differences between the provided send-introspection-query and output from tools you might be using to download the schema (such as apollo-codegen or graphql-cli). If your build is failing, please make sure to try with the provided script. In your project root, run:

$ yarn send-introspection-query <url>