Sequelize Associate: User is not associated to Appointments - node.js

Question

Basically I have a user model and appointment model. The two models are linked with a one-to-many relationship. The Appointment table has two columns that are associated with the user model. When ever I try to include the properties of the user table in appointment, I get the above error.
These are my model designs
Appointment Model
export default ({
sequelize
}:{
sequelize: Sequelize
}) => {
const Appointments: ModelDefined<AppointmentsAttribute, AppointmentsCreationAttributes> = sequelize.define('Appointments', {
appointmentId: {
type: DataTypes.UUID,
defaultValue: DataTypes.UUIDV4,
primaryKey: true,
},
client: {
type: DataTypes.STRING,
allowNull: false,
references: {
model: 'Users',
key: 'uid'
}
},
serviceProvider: {
type: DataTypes.STRING,
allowNull: false,
references: {
model: 'Users',
key: 'uid'
}
},
})
return Appointments
}
User Model
export default ({
sequelize
}: {
sequelize: Sequelize
}) => {
const User: ModelDefined<UserAttribute, UserCreationAttributes> = sequelize.define('User', {
uid: {
type: DataTypes.STRING,
allowNull: false,
unique:true,
primaryKey: true
},
firstname: {
type: DataTypes.STRING,
allowNull: false,
},
lastname: {
type: DataTypes.STRING,
allowNull: false,
},
}
})
return User
}
I have associated the user and appointment models with
Users.hasMany(Appointments);
The code that I am trying to use to fetch the appointment data and include the corresponding user value is
db.appointment.findAll({
where: {
client: this.uid
},
include: 'Users'
})

Answer 1

Sequelize always use associations for models whose association method was called. i.e. if you call Model1.hasMany(Model2) then you can execute queries like:
Model1.findAll({
include: [{
model: Model2
}]
}
and NOT vice versa like this:
Model2.findAll({
include: [{
model: Model1
}]
}
If you wish to request appointment with users as an associated model then you need to add a reversed association from Appointments to Users like this:
Users.hasMany(Appointments);
Appointments.belongsTo(Users);