ectomapper

A lightweight, flexible, and type-safe AutoMapper utility for TypeScript, allowing you to easily map between different object types.

Features

• Type-safe mappings: Leverage TypeScript generics to ensure type safety when mapping between object types.
• Flexible configuration: Define custom mappings between any two types using string keys.

Installation

To install the package:

npm i ectomapper

Usage

Basic example

Here’s how to create and use an AutoMapper in your TypeScript project:

import { createAutoMapper } from 'ectomapper'

// Define your source and destination types
interface SourceType {
  id: number
  name: string
}

interface DestinationType {
  id: number
  fullName: string
}

// Create an instance of AutoMapper
const autoMapper = createAutoMapper()

// Define a map between SourceType and DestinationType
autoMapper.createMap<SourceType, DestinationType>(
  'SourceType',
  'DestinationType',
  (source) => ({
    id: source.id,
    fullName: source.name,
  }),
)

// Use the map to transform an object
const source: SourceType = { id: 1, name: 'John Doe' }
const destination = autoMapper.map<SourceType, DestinationType>(
  source,
  'SourceType',
  'DestinationType',
)

console.log(destination) // Output: { id: 1, fullName: 'John Doe' }

Advanced example

You can define multiple mappings for different types:

interface UserDTO {
  userId: number
  username: string
}

interface User {
  id: number
  name: string
}

// Create mappings
autoMapper.createMap<UserDTO, User>('UserDTO', 'User', (source) => ({
  id: source.userId,
  name: source.username,
}))

autoMapper.createMap<User, UserDTO>('User', 'UserDTO', (source) => ({
  userId: source.id,
  username: source.name,
}))

// Map between UserDTO and User
const userDTO: UserDTO = { userId: 42, username: 'johndoe' }
const user = autoMapper.map<UserDTO, User>(userDTO, 'UserDTO', 'User')

console.log(user) // Output: { id: 42, name: 'johndoe' }

Error Handling

If you attempt to map an object without a corresponding mapping, an error will be thrown:

try {
  const unknownMapping = autoMapper.map<SourceType, DestinationType>(
    source,
    'UnknownSource',
    'UnknownDestination',
  )
} catch (error) {
  console.error(error.message) // Output: No mapping found for key: UnknownSource->UnknownDestination
}

API

createMap

createMap<TSource, TDestination>(
  sourceKey: string,
  destinationKey: string,
  mappingFunction: MapperFunction<TSource, TDestination>
): void

Defines a mapping between two types using the provided string keys.

• sourceKey: A string that identifies the source type.
• destinationKey: A string that identifies the destination type.
• mappingFunction: A function that defines how to map from the source type to the destination type.

map

map<TSource, TDestination>(
  source: TSource,
  sourceKey: string,
  destinationKey: string
): TDestination

Maps an object from the source type to the destination type using the defined mapping.

• source: The object to map.
• sourceKey: The key identifying the source type.
• destinationKey: The key identifying the destination type.
• Returns: The mapped object of the destination type.

Contributing

Contributions are welcome! Please submit issues and pull requests to help improve the package.

License

This project is licensed under the terms of the MIT License.