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https://github.com/nwtgck/ts-json-validator
JSON Validator for TypeScript - Safer JSON.parse() validating by TypeScript types
https://github.com/nwtgck/ts-json-validator
json scheme structure type type-safe typescript validator
Last synced: 22 days ago
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JSON Validator for TypeScript - Safer JSON.parse() validating by TypeScript types
- Host: GitHub
- URL: https://github.com/nwtgck/ts-json-validator
- Owner: nwtgck
- License: mit
- Created: 2019-05-13T08:57:41.000Z (over 5 years ago)
- Default Branch: develop
- Last Pushed: 2021-07-25T16:44:24.000Z (over 3 years ago)
- Last Synced: 2024-10-04T12:53:13.142Z (about 1 month ago)
- Topics: json, scheme, structure, type, type-safe, typescript, validator
- Language: TypeScript
- Homepage:
- Size: 587 KB
- Stars: 26
- Watchers: 4
- Forks: 1
- Open Issues: 9
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# ts-json-validator
[](https://circleci.com/gh/nwtgck/ts-json-validator)
Safer `JSON.parse()` validating by TypeScript types
Write a format of JSON once, Derive the type automatically at compile-time.
## Installation
```bash
npm install -S git+https://github.com/nwtgck/ts-json-validator#v0.1.2
```
## Basic Usage
```ts
import {nul, bool, num, str, literal, opt, arr, tuple, obj, union, TsType, validatingParse} from 'ts-json-validator';
// Create a format
const personFormat = obj({
name: str,
age: num
});
// Generate Person type
// IMPORTANT: Type is derived at compile-time. Just a write format once!
type Person = TsType;
// Safer parse than JSON.parse()
const p1: Person | undefined = validatingParse(personFormat, '{"name": "jack", "age": 8}');
```
```ts
const myObj: {[key: string]: any} = {name: "jack", age: 8};
const p2: Person | undefined = validate(personFormat, myObj);
// => not undefined
```
```ts
const myObj2: any = {name: "jack", age: "this is a text"};
isValid(personFormat.runtimeType, myObj2);
// => false (because type of age should be number)
```
## Core feature
The main feature is that **`type Person` is automatically derived**. So you just define the format/structure object of JSON such as `personFormat`. Then you can get a `type` for free.
## Usage of Array, nested objects, Literal Types, Union Types and Tuples
```ts
import {nul, bool, num, str, literal, opt, arr, tuple, obj, union, TsType, validatingParse} from 'ts-json-validator';
// Create a format
const myObj1Format = obj({
// String array - string[]
myStrs: arr(str),
// Nested object - (myFlag: boolean)
myObj: obj({
myFlag: bool
}),
// Union Type - string | number | bool
strOrNumOrBool: union(str, num, bool),
// Object array - {prop1: number, prop2: string}[]
myObjs: arr(obj({
prop1: num,
prop2: str
})),
// Optional property（myOptional?: number）
myOptional: opt(num),
// Literal Type - (myLiteral: 'MY_LITERAL')
myLiteral: literal('MY_LITERAL' as const),
// Literal Union Type - ('red' | 'blue')
myLitUnion: union(literal('red' as const), literal('blue' as const)),
// Nullable - (string | null)
myNullable: union(str, nul),
// Tuple - [string, boolean, number]
myTuple: tuple(str, bool, num),
});
// Generate MyObj1 type
// IMPORTANT: Type is derived at compile-time. Just write a format once!
type MyObj1 = TsType;
```
In Union Type, `T1 | T2 | ... | T64` is supported. In tuple, `[T1, T2, ..., T64]` is supported.
## Type-safety
You can find errors at compile-time, not runtime!
### Wrong type in the array
`myStrs` should be an string array, but `128` is included.
### Missing property
`myStrs` is required, but missing.
### Wrong Literal Type
`myLiteral` should be `'MY_LITERAL'` type, but found `'YOUR LITERAL'`
### Unknown property
Property `somethingElse` is not defined in `myObj1Format`.
