@edgefirst-dev/data

A TypeScript utility library for safely parsing and handling structured data from various sources such as FormData, URLSearchParams, JSON objects, and more. The Data class provides a structured way to define Data Transfer Objects (DTOs), while specialized parsers allow for type-safe access to form fields, URL search parameters, and generic objects.

Installation

bun add @edgefirst-dev/data

Usage

Importing

To use the Data class, import it from the package root:

import { Data } from "@edgefirst-dev/data";

To use the Parser base class or one of the specialized parsers (FormParser, SearchParamsParser, ObjectParser), import them from the parser module:

import {
  Parser,
  FormParser,
  SearchParamsParser,
  ObjectParser,
} from "@edgefirst-dev/data/parser";

Data Class

The Data class is designed to define a set of properties that can be parsed from a source like FormData, URLSearchParams, or a JSON object. You subclass Data to define specific DTOs, using a parser to extract and validate values.

Example

import { Data } from "@edgefirst-dev/data";
import { FormParser } from "@edgefirst-dev/data/parser";

class LoginData extends Data<FormParser> {
  get username() {
    return this.parser.string("username");
  }

  get password() {
    return this.parser.string("password");
  }
}

const formData = new FormData();
formData.append("username", "johndoe");
formData.append("password", "secret");

const loginData = new LoginData(new FormParser(formData));

console.log(loginData.username); // "johndoe"
console.log(loginData.password); // "secret"

Parser Classes

Parser Base Class

The Parser class is an abstract base class designed for parsing and validating data from structured sources. Specialized parsers extend this class to handle specific data types, ensuring type-safe access to required fields.

FormParser

FormParser is a specialized parser that wraps FormData and provides methods to access form fields in a safe and type-validated way.

Example

import { FormParser } from "@edgefirst-dev/data/parser";

const formData = new FormData();
formData.append("username", "johndoe");

const parser = new FormParser(formData);

console.log(parser.string("username")); // "johndoe"

SearchParamsParser

SearchParamsParser extracts and validates URL query parameters from a URLSearchParams object, URL, Request, or URL string.

Example

import { SearchParamsParser } from "@edgefirst-dev/data/parser";

const url = new URL("https://example.com/?search=query");
const parser = new SearchParamsParser(url);

console.log(parser.get("search")); // "query"

ObjectParser

ObjectParser safely accesses and validates values within a plain JavaScript object, ensuring type correctness for the retrieved values.

Example

import { ObjectParser } from "@edgefirst-dev/data/parser";

const data = { name: "Alice", age: 30 };
const parser = new ObjectParser(data);

console.log(parser.string("name")); // "Alice"
console.log(parser.number("age")); // 30

Error Handling

All parser classes throw specialized errors when validation fails:

• Parser.MissingKeyError: Thrown when a required key is missing.
• Parser.InvalidTypeError: Thrown when a value is not of the expected type.
• Parser.InvalidInstanceOfError: Thrown when a value is not an instance of the expected class.
• Parser.CoercionError: Thrown when a value cannot be coerced to the expected type.

And each one extends the base Parser.Error class, so you can catch all parser errors with a single instanceof condition.

Example

import { ObjectParser } from "@edgefirst-dev/data/parser";

try {
  const data = { name: "Alice", age: 30 };
  const parser = new ObjectParser(data);
  console.log(parser.string("email")); // Throws Parser.MissingKeyError
} catch (error) {
  if (error instanceof Parser.MissingKeyError) {
    // Handle missing key error
  }
  if (error instanceof Parser.Error) {
    // Handle other parser errors
  }
  throw error; // Re-throw unexpected errors
}

License

See LICENSE

Author

• Sergio Xalambrí