https://github.com/ascandone/ts-decode

Straightforward, type-safe `unknown => T` decoding combinators
https://github.com/ascandone/ts-decode

decoding json typesafe typescript validation

Last synced: 3 months ago
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Straightforward, type-safe `unknown => T` decoding combinators

• Host: GitHub
• URL: https://github.com/ascandone/ts-decode
• Owner: ascandone
• Created: 2021-12-02T09:57:34.000Z (over 4 years ago)
• Default Branch: master
• Last Pushed: 2024-02-08T21:38:16.000Z (over 2 years ago)
• Last Synced: 2025-10-06T14:54:49.399Z (9 months ago)
• Topics: decoding, json, typesafe, typescript, validation
• Language: TypeScript
• Homepage: https://ts-decode.netlify.app/modules
• Size: 408 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: readme.md

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README

          
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## `ts-decode`

> Straightforward, type-safe `unknown => T` decoding combinators

### Install

```bash

# using npm

npm i ts-decode

# using yarn

yarn add ts-decode

```

### Usage

```ts

// We can compose the decoders to create new decoders

const personTypeDecoder = oneOf(

  hardcoded("developer"),

  hardcoded("project manager"),

  hardcoded("designer"),

);

const personDecoder = object({

  name: string.required,

  id: number.required,

  kind: personTypeDecoder.required,

  phoneNumbers: array(string).optional,

});

/*

Automagically inferred as:

type Person = {

    name: string;

    id: number;

    kind: "developer" | "project manager" | "designer";

    phoneNumbers?: string[] | undefined;

}

*/

type Person = Infer;

// The decoder can now validate a value of unknown type

const json = JSON.parse(`

  { "name": "John Doe",

    "id": 1234,

    "kind": "project-manager",

    "phoneNumbers": ["123123123"]

  }

`);

const result = personDecoder.decode(json);

if (result.error === false) {

  // now we have the compile-time guarantee that this

  const person = result.value;

  // has type `Person` without manual casting

} else {

  // Or if it failed we can log the error description

  const reason = result.reason;

  console.error(reasonToXmlString(reason));

}

```

By the way, did you notice the bug?

Good thing we printed it out

```xml

  

     Expected "developer", got "project-manager" instead  

     Expected "project manager", got "project-manager" instead  

     Expected "designer", got "project-manager" instead  

  

```

You can find the complete typedocs-generated API [here](https://ts-decode.netlify.app/modules.html) or you can try it in a [codesanbox](https://codesandbox.io/s/ts-decode-playground-xw3yb?file=/src/index.ts)