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:

1. UID: A unique record identifier of the history
2. BeginDate: Record creation date
3. EndDate: Record deletion date
4. 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.

Use the package manager npm to install loopback-component-history.

npm i --save loopback-component-history

Follow these steps to add History extension to your loopback4 application:

• Change your model parent class from Entity to HistoryEntity

• Remove id property from your model declaration

  // Old
  @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);
      }
  }
  
  // New
  import { HistoryEntity } from "loopback-component-history";
  
  @model()
  export class User extends HistoryEntity {
      @property({
          type: "string",
          default: "",
      })
      username: string;
  
      constructor(data?: Partial<User>) {
          super(data);
      }
  }

• Change your repository parent class from DefaultCrudRepository to HistoryRepositoryMixin()()

  // Old
  export class UserRepository extends DefaultCrudRepository<
      User,
      typeof User.prototype.id,
      UserRelations
  > {
      // ...
  }
  
  // New
  import { HistoryRepositoryMixin } from "loopback-component-history";
  
  export class UserRepository extends HistoryRepositoryMixin<
      User,
      UserRelations
  >()<Constructor<DefaultCrudRepository<User, string, UserRelations>>>(
      DefaultCrudRepository
  ) {
      // ...
  }

Don't use unique indexes in your models, instead add unique property to model definition

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,
        unique: true,
    })
    username: string;
}

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

Please make sure to update tests as appropriate.

This project is licensed under the MIT.
Copyright (c) KoLiBer ([email protected])