Installation and setup

Firstly, add decapi and it's peer dependecies to your project

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yarn add decapi graphql reflect-metadata ttypescript

Important! To work with typescript, you'll need reflect-metadata so decapi can infer types from your code.

Add import "reflect-metadata"; somewhere in bootstrap (before any decapi decorator is used) of your app eg app/index.ts.

Configuring tsconfig.json

decapi will try to infer types of your fields, when possible. To allow this, you'll have to add following to your tsconfig.json compilerOptions section:

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    "strictNullChecks": true,

    "emitDecoratorMetadata": true,

    "experimentalDecorators": true,

    "allowSyntheticDefaultImports": true,

    "esModuleInterop": true,

    "plugins": [{ "transform": "typescript-rtti/dist/transformer" }]

Also you need to target es6 or newer target in your compilerOptions. Important! es5 target will not work correctly. ObjectTypes type inference only currently works for es6 or newr targets.

Running with ttypescript

In order to run the rtti transformer, you need to compile using ttypescript. When you develop, you can use ts-node programmatically:

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require('ts-node').register({

  compiler: 'ttypescript',

  transpileOnly: true

})

​

require('./server')

or you can invoke it like this:

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ts-node -C ttypescript server.ts

For production, it's best to compile using ttsc instead of tsc. There's also good reference on ttypescript here: https://github.com/cevek/ttypescript/blob/master/README.md

Does decapi work without typescript?

No we rely on typescript for type inference.