Incremental Type Safety in React Apollo

with Reason
Incremental Type Safety
in React Apollo
Evans Hauser
Core Developer, Apollo

Apollo Project 🚀
import React from 'react';
import { render } from 'react-dom';
import ApolloClient from 'apollo-boost';
import { ApolloProvider } from 'react-apollo';
import App from ‘./App';
const client = new ApolloClient({
uri: ‘https://localhost:3010/graphql'
});
const ApolloApp = () => (
<ApolloProvider client={client}>
<App />
</ApolloProvider>
);
render(ApolloApp, document.getElementById('root'));)
index.js

import FreeJobPost from “./FreeJobPost.js” 
import PromotedPost from “./PromotedPost.js”
…
render() {
...
<FreeJobPost info={info1} />
<PromotedPost info={info4} />
...
}
App.js Adding to the 🚀

npm install bs-platform
npm install reason-react
{
"name": “package-name",
"sources": {
"dir": "src",
"subdirs": [“components"],
},
"reason": {
"react-jsx": 2
},
"refmt": 3
}
bsconﬁg.json
How to add Reason to your 🚀
Build: bsb -make-world
Watch: bsb -make-world -w

import PromotedPost from “./PromotedPost.bs.js”
render() {
...
<PromotedPost info={info4} />
...
}
App.js Inside the 🚀

let component =
ReasonReact.statelessComponent(“PromotedPost”);
let make = (~info, _children) => {
...component,
render: (self) =>
<div>
<Post text=info.text timeLeft=info.timeLeft />
</div>
};
let default =
ReasonReact.wrapReasonForJs(
~component,
(props) => make(~info=settingsInfoFromJs(props##info), [||])
);
PromotedPost.re Adding Reason

PromotedPost.re Adding Reason
let component =
...component,
render: (self) =>
<div>
</div>
};
let default =
~component,
);

let component =
ReasonReact.statelessComponent(“Post”);
let make = (~text, ~timeLeft, _children) => {
…component,
render: (self) =>
<input
_type=“checkbox”
value=text
checked=(text > 0)
/>
};
Post.re Reason Subcomponent

let component =
…component,
render: (self) =>
<input
value=text
checked=(timeLeft > 0)
/>
};
Post.re Reason Subcomponent

let component =
…component,
render: (self) =>
<input
value=text
checked=(Js.Boolean.to_js_boolean(timeLeft > 0))
/>
};
Post.re Javascript Interop

PromotedPost.re More Interop
let component =
...component,
render: (self) =>
<div>
<p>Promoted Posting:</p>
</div>
};
let default =
~component,
);

type postInfo = {.
“text”: string,
“timeLeft”: number
};
let postInfoFromJs = (jsInfo : postInfo) => {
text: jsInfo##text,
timeLeft: jsInfo##timeLeft
};
const examplePosting = {
“text”: “description of posting”,
“timeLeft”: 200
};
Defining TypesPromotedPost.re
App.js

What about GraphQL 🤔
Typed Query Language
Strong Reason support

Creating separation through GraphQL

npm install graphql_ppx
npm install reason_apollo
{
"bs-dependencies": [
"reason-react",
“reason-apollo"
],
"ppx-flags": [
"./node_modules/graphql_ppx/ppx -ast-out"
],
}
bsconﬁg.json
Adding GraphQL to your 🚀

Separation through GraphQL
module PromotedPostQuery = [%graphql {|
query getPromotedPosts {
info {
text
timeLeft
}
}
|}];
let promotedPosts = PromotedPostQuery.make(());
GqlPost.re

let component = ReasonReact.statelessComponent("PromotedPost");
[@bs.module "react-apollo"] external gql: 'a =>
[@bs] ReasonReact.reactClass => ReasonReact.reactClass = "graphql";
let wrap = (gql (promotedPosts##query));
let default =
[@bs] wrap (ReasonReact.wrapReasonForJs(
~component,
(props : {..
"data": {..
"data": TodosQuery.t,
"loading": Js.boolean,
}
}) => make(~result=props, [||])
)
));
GqlPost.re

A Possible API
module PromotedPostQuery = [%graphql {|
query getPromotedPosts {
info {
text
timeLeft
}
}
|}];
let make = (~result, _children) => {
...component,
render: (self) =>
if(Js.to_bool (result##loading)){
<div> <String text="Loading"/> </div>
} else {
let text = result##data##info##text;
let timeLeft = result##data##info##timeLeft;
<div>
</div>
}
};
let default = ReasonApollo.graphql (PromotedPostsQuery) {"PromotedPost", make);

Let’s collaborate!
Evans Hauser
@evanshauser
evans@apollograpql.com
• Next Steps:
• Ensure that your types work
across the client server
boundary
• Manage client-side state with
apollo-link-state
Huge thank you to Ben Souci for his
help putting together this talk!

Incremental Type Safety in React Apollo

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