Adonis HasOne - JavaScript

Introduction

Adonis HasOne is a JavaScript library that enables developers to easily implement the HasOne relationship between two database tables in AdonisJS framework.

HasOne relationship refers to a one-to-one relationship between two database tables, where one record in the parent table is linked to only one record in the child table.

Adonis HasOne simplifies the relationship implementation process by providing easy-to-use methods to retrieve and store related data in the linked tables.

Installation

Adonis HasOne can be installed using npm:

npm install --save adonis-hasone

Usage

To use Adonis HasOne, we need to define two models that represent the parent and child tables.

The parent model should define the hasOne relationship to the child model, and specify the foreign key to be used.

For example, consider a database with users and profiles tables. We can define the models as follows:

// app/Models/User.js

const HasOne = require('adonis-hasone').HasOne

class User extends Model {
  profile () {
    return this.hasOne('App/Models/Profile', 'id', 'user_id')
  }
}

// app/Models/Profile.js

class Profile extends Model {
  user () {
    return this.belongsTo('App/Models/User', 'user_id', 'id')
  }
}

Here, the User model defines the hasOne relationship to the Profile model, with the foreign key user_id. Similarly, the Profile model defines the inverse belongsTo relationship to the User model.

With these relationships defined, we can easily fetch related data using the load method:

const user = await User.find(1)
await user.load('profile') // Fetches the profile record associated with the user

We can also save related data using the associate method:

const user = await User.find(1)
const profile = new Profile()
profile.username = 'johndoe'
await user.profile().save(profile)

This will create a new Profile record in the database with the foreign key user_id set to 1, thus linking it to the User record.

Conclusion

Adonis HasOne is a powerful library that simplifies the implementation of the HasOne relationship between two database tables in AdonisJS. Its easy-to-use methods can help developers save time and reduce code complexity in their projects.