How to check condition from child model in sequelize?

Question

We want to include model if parent model has certain column, so is there any way to achieve this ?

Notification.findAll({
 include: [{
          model: this.StudentTaskModel,
          attributes: ['title'],
          as: 'student_task',
          required: false,
          where: {
            '$Notifications.object_type$': 'student task'
          }
        }, {
          model: this.UserRequestModel,
          attributes: ['type', 'comment'],
          as: 'user_request',
          required: false,
          where: {
            '$Notifications.object_type$': 'user request'
          }
        }],
        order: [
          [orderBy, orderType]
        ],
        where: {
          user_id: user.id
        }
})

But this is throwing error

 SequelizeDatabaseError: Unknown column 'Notifications.object_type' in 'on clause'

But there is column "object_type" in parent model

So, is there any mistake with this code ?

My association is like this

 Notification.associate = function (models) {
    Notification.belongsTo(models.User, {
      foreignKey: 'user_id',
      sourceKey: 'id',
      as: 'user'
    })

    Notification.belongsTo(models.StudentTask, {
      foreignKey: 'object_id',
      sourceKey: 'id',
      as: 'student_task'
    })

    Notification.belongsTo(models.UserRequest, {
      foreignKey: 'object_id',
      sourceKey: 'id',
      as: 'user_request'
    })
  };