Sequelize and Typescript without association techniques

Although I don't consider my problem to be the most challenging, I've been struggling to make any headway with it for quite some time.

What is the issue I'm facing?

In my backend, I am using sequelize alongside typescript and I am attempting to establish associations between tables/models (specifically many-to-many relationships). However, after setting up these associations, I am unable to utilize the "magic methods" provided by sequelize to facilitate these associations.

// defined association between tasks and employees

const task = await DB.Tasks.findByPk(1) 
// task.addEmployee() or similar methods are missing! 

Using sequelize v6.37.2

What steps have I taken so far?

Before delving into my code, I feel it is important to share some key details first.

console.log(mymodel.associations) // successfully executed without errors  

This will display my defined association. I have also scoured GitHub for repositories utilizing a similar model structure to mine (following the official sequelize docs template) but have found no solutions. I have made efforts to adhere to the guidelines provided in the official sequelize documentation:

https://sequelize.org/docs/v6/other-topics/typescript/

My Implementation

Below is one of my models (the other model follows the same structure):

// Task interface defining all attributes
export type TaskCreationAttributes = Optional<Task, "id">

export class TaskModel extends Model<Task, TaskCreationAttributes> {
    declare id: number
    declare name: string
    declare description: string
}

export default function (sequelize: Sequelize): typeof TaskModel {
    TaskModel.init(
        {
            id: {
                autoIncrement: true,
                primaryKey: true,
                type: DataTypes.INTEGER,
            },
            name: {
                allowNull: false,
                type: DataTypes.STRING(255),
            },
            description: {
                allowNull: true,
                type: DataTypes.TEXT,
            } 
        },
        {
            tableName: "tasks",
            sequelize,
        },
    )

    

    TaskModel.belongsToMany(EmployeeModel, { through: "task_positions"})
    EmployeeModel.belongsToMany(TaskModel, { through: "task_positions"})

    return TaskModel
}

Answer №1

To tap into the power of Sequelize's "magic" methods, be sure to specifically define them by utilizing the mixin interfaces supplied by Sequelize. Take a look at the provided link for more information:

let employees: BelongsToManyGetAssociationsMixin<Emplyee>;

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