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MIT
Using Apollo client 2 with Reason

Reason-apollo

npm version Get on Slack

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 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 it's usage in this video:

Watch reason-apollo usage here

Usage

Create the Apollo Client

Client.re

  • RE
  • ML
/* 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, 
 ()
);
let inMemoryCache = ApolloInMemoryCache.createInMemoryCache ()
let httpLink =
  ApolloLinks.createHttpLink ~uri:"http://localhost:3010/graphql" ()
let instance =
  ReasonApollo.createApolloClient ~link:httpLink ~cache:inMemoryCache ()

ApolloProvider

Index.re

  • RE
  • ML
  /* 
    Enhance your application with the `ReasonApollo.Provider` 
    passing it your client instance 
  */
  ReactDOMRe.renderToElementWithId(
    <ReasonApollo.Provider client=Client.instance>
        <App />
    </ReasonApollo.Provider>
  , "index");
let _ =
  ReactDOMRe.renderToElementWithId
    ((ReasonApollo.Provider.createElement ~client:Client.instance
        ~children:[((App.createElement ~children:[] ())[@JSX ])] ())[@JSX ])
    "index"

Query

MyComponent.re

  • RE
  • ML
/* 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>
}
}
3321: <UNKNOWN SYNTAX ERROR>

Mutation

MyMutation.re

  • RE
  • ML
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>
}
}
unknown refmt error

ApolloConsumer

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

  • RE
  • ML
<ApolloConsumer>
  ...((apolloClient) => {
    /* We have access to the client! */
  })
</ApolloConsumer>
let _ =
  ((ApolloConsumer.createElement
      ~children:(fun apolloClient  -> object (this)  end) ())[@JSX ])

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:

  • RE
  • ML
switch response##object {
| Some(object) => {
  switch object##nestedValue {
  | Some(nestedValue) => nestedValue
  | None => ""
  }
}
| None => ""
}
300: object is a reserved keyword, it cannot be used as an identifier. Try `object_' instead

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

  • RE
  • ML
type object = {
  nestedValue: option(string)
}


module GetObject = [%graphql {|
  object @bsRecord {
    nestedValue
  }
 |}
];
188: object is a reserved keyword, it cannot be used as an identifier. Try `object_' instead

This time we can pattern match more precisely.

  • RE
  • ML
switch response##object {
| Some({ nestedValue: Some(value) }) => value
| Some({ nestedValue: None }) => ""
| None => ""
}
300: object is a reserved keyword, it cannot be used as an identifier. Try `object_' instead

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:

  • RE
  • ML
{
    Object {
      id
      title
    }
}
967: syntax error, consider adding a `;' before

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

  • RE
  • ML
response##Object /* Does not work :( */
let _ = ## response Object

Instead, use an alias to modify the response:

  • RE
  • ML
{
    object: Object {
      id
      title
    }
}
3321: <UNKNOWN SYNTAX ERROR>

Then you can access the object like this:

  • RE
  • ML
response##object
571: object is a reserved keyword, it cannot be used as an identifier. Try `object_' instead

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>