@typeonly/validator-cli

TypeOnly aims to be the pure typing part of TypeScript. This package provides a Command Line Interface to validate JSON with TypeScript definitions, using the TypeOnly parser.

Tutorial: How to validate the conformity of a JSON file using the CLI

Create a file "drawing.d.ts" with the following code:

// drawing.d.ts

export interface Drawing {
  color: ColorName
  dashed?: boolean
  shape: Rectangle | Circle
}

export type ColorName = "red" | "green" | "blue"

export interface Rectangle {
  kind: "rectangle",
  x: number
  y: number
  width: number
  height: number
}

export interface Circle {
  kind: "circle",
  x: number
  y: number
  radius: number
}

Then, create a JSON file "drawing.json" that must be of type Drawing:

{
  "color": "green",
  "shape": {
    "kind": "circle",
    "x": 100,
    "y": 100,
    "radius": "wrong value"
  }
}

We are ready to validate the JSON file:

$ npx @typeonly/validator-cli -s drawing.d.ts -t "Drawing" drawing.json
In property 'radius', value '"wrong value"' is not conform to number.

A mistake is detected in the JSON file. Fix it by replacing the value of the property "radius" with a valid number. For example: "radius": 50. And run the command again:

$ npx @typeonly/validator-cli -s drawing.d.ts -t "Drawing" drawing.json

Good. The validator no longer complain.

Options of Command Line Interface

Example of command:

npx @typeonly/validator-cli -s src/file-name.d.ts -t RootTypeName data.json

Available options:

  -h, --help                       Print this help message.
  -s, --source file.d.ts           The typing file (one file allowed).
  --source-encoding string         Encoding for typing files (default is utf8).
  --source-dir directory           The source directory that contains typing files (optional).
  --rto-module file.rto.json       The rto.json file to process (one file allowed).
  --rto-dir directory              The source directory for rto.json file (optional).
  -t, --type string                The type name of the root element in JSON.
  --non-strict                     Enable non-strict mode (accept extra properties).
  -e, --json-encoding string       Encoding for JSON file to validate (default is utf8).
  --json file.json                 The JSON file to validate (by default at last position, one file allowed).

Contribute

With VS Code, our recommanded plugin is:

• TSLint from Microsoft (ms-vscode.vscode-typescript-tslint-plugin)