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https://github.com/apollographql/reason-apollo

Reason binding for Apollo Client and React Apollo
https://github.com/apollographql/reason-apollo

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Reason binding for Apollo Client and React Apollo

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README

        

# Archival
This repo was archived by the Apollo Security team on 2023-05-26

# Reason-apollo

[![npm version](https://badge.fury.io/js/reason-apollo.svg)](https://badge.fury.io/js/reason-apollo)
[![Join the community on Spectrum](https://withspectrum.github.io/badge/badge.svg)](https://spectrum.chat/apollo)

> react-apollo with ReasonML

## Install and setup

#### Install

```
yarn add reason-apollo

# Add graphql_ppx
yarn add @baransu/graphql_ppx_re --dev
```

#### bsconfig

Add `reason-apollo` to your `bs-dependencies` and
`@baransu/graphql_ppx_re/ppx` to your `ppx-flags`

**bsconfig.json**

```
"bs-dependencies": [
"reason-react",
"reason-apollo"
],
"ppx-flags": [
"@baransu/graphql_ppx_re/ppx"
]
```

#### Send introspection query

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

```
npx get-graphql-schema ENDPOINT_URL -j > graphql_schema.json
```

## Why reason-apollo?

Watch its usage in this video:

[![Watch reason-apollo usage here](https://i.ytimg.com/vi/yMqE37LqRLA/hqdefault.jpg?sqp=-oaymwEZCNACELwBSFXyq4qpAwsIARUAAIhCGAFwAQ==&rs=AOn4CLD9rxIyXtckkxmGAxRn_Uv2mDcXcQ)](https://www.youtube.com/watch?v=yMqE37LqRLA)

# Usage

## Create the Apollo Client

**Client.re**

```reason
/* 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**

```reason
/*
Enhance your application with the `ReasonApollo.Provider`
passing it your client instance
*/
ReactDOMRe.renderToElementWithId(


,
"index",
);
```

## Query

**MyQuery.re**

```reason
/* Create a GraphQL Query by using the graphql_ppx */
module GetUserName = [%graphql
{|
query getUserName($id: ID!){
user(id: $ID) {
id
device {
id
brand {
id
name
}
}
}
}
|}
];

module GetUserNameQuery = ReasonApollo.CreateQuery(GetUserName);

[@react.component]
let make = () => {
let userNameQuery = GetUserName.make(~id="42", ());

...{({result}) =>
switch (result) {
| Loading =>

{ReasonReact.string("Loading")}

| Error(error) =>
{ReasonReact.string(error##message)}

| Data(response) =>

{/* Handles a deeply nested optional response */
response##user
->Belt.Option.flatMap(user => user##device)
->Belt.Option.flatMap(device => device##brand)
->Belt.Option.mapWithDefault("", brand => brand##name)}

}
}
;
};

```

## Mutation

**MyMutation.re**

```reason
module AddUser = [%graphql
{|
mutation addUser($name: String!) {
addUser(name: $name) {
id
name
}
}
|}
];

module AddUserMutation = ReasonApollo.CreateMutation(AddUser);

[[@react.component]
let make = () => {

...{(mutation /* Mutation to call */, _ /* Result of your mutation */) => {
let addNewUserQuery = AddUser.make(~name="Bob", ());



mutation(
~variables=addNewUserQuery##variables,
~refetchQueries=[|"getAllUsers"|],
(),
)
|> ignore
}>
{ReasonReact.string("Add User")}

;
}}
;
};
```

## Subscription

**MySubscription.re**

```reason
module UserAdded = [%graphql {|
subscription userAdded {
userAdded {
id
name
}
}
|}];

module UserAddedSubscription = ReasonApollo.CreateSubscription(UserAdded);

[@react.component]
let make = () => {

...{({result}) => {
switch (result) {
| Loading =>

{ReasonReact.string("Loading")}

| Error(error) =>
{ReasonReact.string(error##message)}

| Data(_response) =>




}
}}
;
};
```

## ApolloConsumer

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

```reason

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

## Tips and Tricks

### access deeply nested optional objects

If for this query

```graphql
query {
user {
device {
brand {
name
}
}
}
}
```

you end up with that kind of code:

```reason
let deviceName =
switch (response##user) {
| None => ""
| Some(user) =>
switch (user##device) {
| None => ""
| Some(device) =>
switch (device##brand) {
| None => ""
| Some(brand) => brand##name
}
}
};

```

1. Use `Belt`

```reason
open Belt.Option;

let deviceName =
response##user
->flatMap(user => user##device)
->flatMap(device => device##brand)
->mapWithDefault("", brand => brand##name);
```

2. Use `@bsRecord`

The `@bsRecord` modifier is an [extension](https://github.com/reasonml-community/graphql_ppx#record-conversion) 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, but you need to defined the record by yourself.

```reason
type brand = {
name: string
};

type device = {
brand: option(brand)
};

type user = {
device: option(device)
};

type response = user;

query {
user @bsRecord {
device @bsRecord {
brand @bsRecord {
name
}
}
}
}
```

This time we can pattern match more precisely.

```reason
let deviceName =
switch (response##user) {
| Some({device: Some({brand: {name}})}) => name
| _ => ""
};

```

3. Use `get_in_ppx`

`npm install get_in_ppx`
and in `bsconfig.json`
`"ppx-flags": ["get_in_ppx/ppx"]`
you can write

```reason
let deviceName = response##user#??device#??brand#?name;
```

There's a [blogpost](https://jaredforsyth.com/posts/optional-attribute-access-in-reason/) from Jared Forsyth (author of this ppx) for more explanation.

### 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:

```reason
{
Object {
id
title
}
}
```

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

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

Instead, use an `alias` to modify the response:

```reason
{
object: Object {
id
title
}
}
```

Then you can access the object like this:

```reason
response##object
```

### Generic Error and Loading components

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

```reason
module QueryView = {
[@react.component]
let make =
(
~result: ReasonApolloTypes.queryResponse('a),
~accessData: 'a => option('b),
~render: ('b, 'c) => React.element,
~onLoadMore: ('b, 'unit) => unit=(_, ()) => (),
) => {
switch (result) {
| Error(error) =>
| Loading => ReasonReact.null
| Data(response) =>
switch (accessData(response)) {
| Some(data) => render(data, onLoadMore(data))
| _ =>
}
};
};
};

```

## 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:

```
npx get-graphql-schema ENDPOINT_URL -j > graphql_schema.json
```