ts-matches-json-schema

The problem that we want solved is that we have generated out some JSON-Schema, but we would like the types in typescript. As well, we would like to validate these types are valid (throw/ case switch).

So this is going to be a subset of the potential json schema. If I can't get a typescript type from the schema, then I'm not going to make the validation. If you want to have full validation, but no typescript types, something like AJV.js is going to fit your bill better.

Example Usuage

Usage of converting from a schema to a parser/ ts-matcher

// Here we have brought in the test schema. This schema was cloned off
// https://json-schema.org/learn/getting-started-step-by-step.html
// except the reference.
// Notice: There is the `as const`. Currenlty one cannot import from csv with the const
const testSchema = {
  $schema: "http://json-schema.org/draft-07/schema#",
  $id: "http://example.com/product.schema.json",
  title: "Product",
  description: "A product from Acme's catalog",
  type: "object",
  properties: {
    productId: {
      description: "The unique identifier for a product",
      type: "integer",
    },
    productName: {
      description: "Name of the product",
      type: "string",
    },
    isProduct: {
      description: "Name of the product",
      type: "boolean",
    },
    price: {
      description: "The price of the product",
      type: "number",
      exclusiveMinimum: 0,
    },
    tags: {
      description: "Tags for the product",
      type: "array",
      items: {
        type: "string",
      },
      minItems: 1,
      uniqueItems: true,
    },
    extras: {
      description: "Tags for the product",
      type: "array",
      minItems: 1,
      uniqueItems: true,
    },
    dimensions: {
      type: "object",
      properties: {
        length: {
          type: "number",
        },
        width: {
          type: "number",
        },
        height: {
          type: "number",
        },
      },
      required: ["length", "width", "height"],
    },
  },
  required: ["productId", "productName", "price"],
} as const;

// Here we create our matcher
const matchTestSchema = asSchemaMatcher(testSchema);
// If we want to pull out the generated type from the matcher for typescript
type TestSchema = typeof matchTestSchema._TYPE;

// Here we are going to create a json to test the shape
const validShape = {
  productId: 0,
  price: 0.4,
  productName: "test",
  tags: ["5"],
  extras: ["string", 4],
  isProduct: false,
  dimensions: {
    length: 7.0,
    width: 12.0,
    height: 9.5,
  },
};

// So here, we are going to validate the shape.
// Note: Return type of unsafeCast is TestSchema here, so we don't manually
// need to tell typescript what the type is.
// Note: If this fails with unsafeCast, it will throw. There are other methods in the validator that will not throw.
const validShape: TestSchema = matchTestSchema.unsafeCast(validShape);

Convert a parser into a schema

import { literal, shape } from "https://deno.land/x/[email protected]/mod.ts";
const matcher = shape({ a: literal(5), b: literal("5").name("Is_string_5") }, ["b"]);
const schema = toSchema(matcher);
assertEquals(schema, {
  allOf: [
    {
      type: "object",
      properties: {
        b: { $ref: "#/definitions/Is_string_5" },
      },
      required: [],
    },
    {
      type: "object",
      properties: {
        a: {
          type: "number",
          enum: [5],
        },
      },
      required: ["a"],
    },
  ],
  definitions: { Is_string_5: { type: "string", enum: ["5"] } },
});

Features

• [x] Convert parser into a schema
• [x] Simple Type Validation
• [x] Enum Type Validation
• [x] allOf/ anyOf type
• [x] Type allowed to be array of types
• [x] References to other schemas
• [ ] Limit Validations (min/ max)