@onehop/json-methods
v1.2.0
Published
A utility for adding methods to any JSON object. For example, deserializing a user object from your API and adding a `.isAdult()`. Whilst this library works great for validation, use cases extend far beyond that. It was built for `@onehop/js` to enable re
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json-methods
A utility for adding methods to any JSON object. For example, deserializing a user object from your API and adding a .isAdult()
. Whilst this library works great for validation, use cases extend far beyond that. It was built for @onehop/js
to enable regular objects to have utility methods that are context aware (like fetching a deployment's containers in Hop).
Installation
# With yarn
yarn add @onehop/json-methods
# With npm
npm install --save @onehop/json-methods
Basic Example
For something a little bit more in depth, but still simple, check out /examples/basic.ts
import {create} from '@onehop/json-methods';
interface User {
id: string;
email: string;
age: number;
}
const Users = create<User>().methods({
// Methods must be created with method function syntax,
// rather than property arrow functions (so that `this` can be bound)
isAdult() {
return this.age >= 18;
},
});
// json is the JSON object that we want to add methods to
const json = await getUserFromAPI();
const user = Users.from(json);
// Or, if you have a JSON string, we can parse it for you
const user = Users.parse(json);
// Safely access properties:
console.log(user.email);
// And call our methods
console.log('Can watch the movie?:', user.isAdult());
Validation / Schemas
json-methods
supports third-party schemas out of the box. You can write your own, or use things like Zod, Yup or Joi. The precondition is that the schema object itself has a method with the signature parse(data: unknown): T
Here's a basic example using Zod:
import {create} from '@onehop/json-methods';
import {z} from 'zod';
// This schema has a .parse method internally, so it will work
// with json-methods without any modification
const schema = z.object({
age: z.number().min(0),
});
const Users = create(schema).methods({
isAdult() {
return this.age >= 18;
},
});
// During this phase, the schema will be used to validate the passed object.
// If you do not pass a schema, then the raw data will be used, but you
// could run into runtime errors if you try to access properties that don't exist!
// For this reason, it's recommended to always pass a schema if you can
const user = Users.from(await getUserFromAPI());
console.log('Can watch the movie?:', user.isAdult());
Advanced TypeScript
For more advanced use cases, there's a type exported called Infer
that will allow you to get the full type of your object with the methods added
import {create, Infer} from '@onehop/json-methods';
const Users = create<{age: number}>().methods({
isAdult() {
return this.age >= 18;
},
});
// UserWithMethods is {age: number} & {isAdult(): boolean}
type UserWithMethods = Infer<typeof Users>;