Loopback-history-extension NPM

loopback-history-extension

Saving history of Create, Update, Delete of a table sometimes is a big problem in data model design level.

A good approach for saving history is about adding some columns to your tables:

UID: A unique record identifier of the history
BeginDate: Record creation date
EndDate: Record deletion date
ID: History of one data is accessable using their same ID

Per every Create we will create a new record in table
Per every Update we will invalid last history, create new record
Per every Delete we will invalid last history

Now, using this simple extension you can add all history features to your models and repositories.

Installation

npm i --save loopback-history-extension

Usage

History Model

Change your model parent class from Entity to HistoryEntity
Remove id property from your model declaration

Example

Change your model from:

@model()
export class User extends Entity {
    @property({
        type: "string",
        unique: true,
        id: true
    })
    id: string;

    @property({
        type: "string",
        default: ""
    })
    username: string;

    constructor(data?: Partial<User>) {
        super(data);
    }
}

To:

import { HistoryEntity } from "loopback-history-extension";

@model()
export class User extends HistoryEntity {
    @property({
        type: "string",
        default: ""
    })
    username: string;

    constructor(data?: Partial<User>) {
        super(data);
    }
}

Tip

Don't use unique columns in your models

Convert your model from:

export class User extends Entity {
    @property({
        type: "string",
        required: true,
        index: {
            unique: true
        }
    })
    username: string;
}

To:

export class User extends HistoryEntity {
    @property({
        type: "string",
        required: true
    })
    username: string;
}

History Repository Mixin

Change your repository parent class from DefaultCrudRepository to HistoryCrudRepositoryMixin()()

Example

Change your repository from:

export class UserRepository extends DefaultCrudRepository<
    User,
    typeof User.prototype.id,
    UserRelations
> {
    // ...
}

To:

import { HistoryCrudRepositoryMixin } from "loopback-history-extension";

export class UserRepository extends HistoryCrudRepositoryMixin<
    User,
    UserRelations
>()() {
    // ...
}