TypeParams Plugin

TypeParams Plugin is a TypeScript-first replacement for UrlSearchParams that allows you to apply type discipline to your query parameters such that reads and writes are safely protected. Furthermore, thanks to a Babel plugin, it will even coerce values for you automatically (ie, no need for parseInt).

Features

• Automatically generates validation schemas based on TypeScript types.
• Automatic type coercion (eg. string "3" -> integer 3)
• Lightweight integration with minimal configuration.
• Works seamlessly with URL query strings.

Installation

Install the plugin via your package manager:

yarn add @shmax/typeparams

Configuration

Create an (optional) typeparams.config.ts file in the root of your project:

export default {
  outputDir: ".generated-schemas", // defaults to .generated-schemas
};

Add the plugin to your Babel configuration (e.g., .babelrc or Babel section in package.json):

{
  "presets": ["@babel/preset-env", "@babel/preset-typescript"],
  "plugins": ["@shmax/typeparams/plugin"]
}

Run the tool to generate schemas (add --watch to have it automatically re-generate schemas after changes):

typeparams-gen --watch

Usage

1. Define Your Url schema as a TypeScript interface

type Filters = {
  filters: {
    toyline: number;
    tags: string[];
    metadata: {
      createdBy: string;
      active: boolean;
    };
  };
};

2. Feed it to an instance of the TypeParams Class as a generic argument

import { TypeParams } from "typeparams-plugin/shared/url-structured-search-params";

const params = new TypeParams<Filters>("?filters_toyline=3&filters_tags=toy1,toy2");

// or, for more safety:
const params = new TypeParams<Filters>({filters: { toyline: 3, tags: ['toy1', 'toy2']}});

// Safely get a value by its key path
const toyline = params.get("filters.toyline"); // OK
const brand = params.get("filters.brand"); // TS error! property "brand" doesn't exist on "filters"' 

3. Any values you retrieve are automatically coerced into the expected type

console.log(typeof toyline, toyline); // number 3

4. Set values with the same type discipline

// Set a value safely
params.set("filters.toyline", 3); // OK
params.set("filters.toyline", "3"); // TS error! Property "toyline" expects a number
params.set("filters.whammy", true); // TS error! Property "whammy" doesn't exist

5. Can also clear values

// Clear a key
params.clear("filters.tags");

// Serialize back to a string ts navigate(`?${params}`) // ?filters_toyline=3&filters_tags=toy1,toy2

Example Output

When running your project, the plugin generates schema files in .generated-schemas (or the directory you specify in typeparams.config.ts). These schemas are automatically used during runtime for validation.

Requirements

• Node.js 14+
• TypeScript 4.0+

FAQ

Q: Do I need to configure anything else?
A: Nope! Just add the plugin to your Babel setup and define your types. The plugin handles the rest. Oh, and you may want to add the name of the generated schema directory to your .gitignore

Q: Does this work with non-TypeScript projects?
A: No, this plugin is designed specifically for TypeScript-first projects.

License

MIT