JSON Schema to TypeScript

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题目

Implement the generic type JSONSchema2TS which will return the TypeScript type corresponding to the given JSON schema.

Additional challenges to handle:

• additionalProperties
• oneOf, anyOf, allOf
• minLength and maxLength

解答

type Primitives = {
  string: string;
  number: number;
  boolean: boolean;
};

type HandlePrimitives<T, Type extends keyof Primitives> = T extends {
  enum: unknown[];
}
  ? T['enum'][number]
  : Primitives[Type];

type HandleObject<T> = T extends {
  properties: infer Properties extends Record<string, unknown>;
}
  ? T extends { required: infer Required extends unknown[] }
    ? Omit<
        {
          [K in Required[number] & keyof Properties]: JSONSchema2TS<
            Properties[K]
          >;
        } & {
          [K in Exclude<keyof Properties, Required[number]>]?: JSONSchema2TS<
            Properties[K]
          >;
        },
        never
      >
    : {
        [K in keyof Properties]?: JSONSchema2TS<Properties[K]>;
      }
  : Record<string, unknown>;

type HandleArray<T> = T extends { items: infer Items }
  ? JSONSchema2TS<Items>[]
  : unknown[];

type JSONSchema2TS<T> = T extends { type: infer Type }
  ? Type extends keyof Primitives
    ? HandlePrimitives<T, Type>
    : Type extends 'object'
    ? HandleObject<T>
    : HandleArray<T>
  : never;