JS-ORM

About

A simple library that allows you to map the backend API responses to the desired front-end data model and vice versa.

Installation

Run:

npm i js-orm-lib

Import in your project like this:

import { mapFieldsFromApi, mapFieldsForApi } from 'js-orm-lib'

Usage

Use the mapFieldsFromApi to map the data to the desired front-end object structure. Use the mapFieldsForApi to map the previously changed object back to the backend structure.

Examples:

Let's say you are receiving the following data from the API:

const mockAPIData = {
    data: {
        fullName: 'Homer Simpson',
        ageNumber: 40,
        location: {
            town: 'SpringField',
        },
    },
    favoriteFood: ['beer', 'pizza', 'burger'],
};

We can do:

const mapping = {
    name: 'data.fullName', // This maps the data in 'data.fullName' to the name field
    age: 'data.ageNumber',
    homeTown: 'data.location.town',
    likedFood: 'favoriteFood',
    firstName: (mappedData, response) => {  // We can create new fields with functions if we need additional transformation on the data
        return response.data.fullName.split(' ')[0];
    },
    birthYear: (mappedData, response) => {
        const date = new Date();
        date.setFullYear(date.getFullYear() - mappedData.age)
        return date.getFullYear();
    },
    transformFromApi: (mappedData, response) => { // This allows us to manipulate the object as a whole
        return {
            ...mappedData,
            beersPerDay: 1,
        };
    },
    transformForApi: (mappedData) => { // This function will be called when calling the mapFieldsForApi()
        return {
          ...mappedData,
          needsMoreBeer: true,
        }
    },
};

const mappedResult = mapFieldsFromApi(mockAPIData, mapping);

Note that if you use a function value or call the transformFromApi you need to implement the transformForApi, otherwise the library will throw an error. This is to minimise the chance of sending back and invalid data.

All the string path mappings will be reverse mapped when calling mapFieldsForApi, the function fields and fields added with transformFromApi will stay on the object. For example if we call mapFieldsForApi(mappedResult, mapping) on the above data, we will get:

...fields added by functions
data: {
    fullName: 'Homer Simpson',
    ageNumber: 40,
    location: {
        town: 'SpringField',
    },
},
favoriteFood: ['beer', 'pizza', 'burger'],

Nested mapping: We can also map values into nested fields using a mapping configuration like this:

const mapping = {
    ['data.name']: 'data.fullName',
    ['data.age']: 'data.ageNumber',
    ['data.homeTown']: 'data.location.town',
    ['data.food.likedFood']: 'favoriteFood',
};
const mappedResult = mapFieldsFromApi(mockAPIData, mapping);

This will output:

data: {
    name: 'Homer Simpson',
    age: 40,
    homeTown: SpringField,
    food: {
        likedFood: ['beer', 'pizza', 'burger'],
    },
}

Entity name: If you specify an entityName on the mapping configuration, the mapFieldsForApi will place all the data inside a field by that name: E.g.:

const mapping = {
    entityName: 'simpson',
    ...
};

Will give you:

simpson: {
    ... rest of your data
}