当参数描述关系时如何将查询参数传递给续集

Question

For instance, I have model Student and a couple of models that relates to it. Let it be Class , Absence and Grade .

Definitions for this models:

var Student = sequelize.define('Student', {
    class_id : DataTypes.INTEGER,
    name : DataTypes.INTEGER,
    gender : DataTypes.ENUM('male', 'female')
    is_paid : DataTypes.BOOLEAN
})

var Class = sequelize.define('Class', {
    name : DataTypes.STRING
})

var Absense = sequelize.define('Absense', {
    student_id : DataTypes.INTEGER
    date : DataTypes.DATEONLY,
})

var Grade = sequelize.define('Grade', {
    student_id : 
    subject : DataTypes.ENUM('singing', 'dancing')
    value : DataTypes.INTEGER
})

Absense.belongsTo(Student, { foreign_key : 'student_id' });
Grade.belongsTo(Student, { foreign_key : 'student_id' })

I want to add endpoint to list entities for this model. But also I want to allow to use optional filters in this endpoint. So both of this usages will be possible:

• GET api.acme.com/v0.1/users
• GET api.acme.com/v0.1/users? class=1,3 &gender=male &is_paid=true &absences=true &avg_grade=gt:3 &limit=20&offset=0&order=avg_grade%20DESC

While I handle params that present in Student , it's easy:

var condition = {};

req.params.is_paid && condition.is_paid = boolean(req.params.is_paid);
req.params.gender && condition.gender = { $in : req.params.gender.split(',') };
req.params.class && condition.class = { $in : req.params.class.split(',') };

res.json(await Student.findAll({
    where : condition,
    limit : req.query.limit || 20,
    offset : req.query.offset || 0,
    order : req.query.order || 'id ASC'
}))

But when I want to add implement absense or avg_grade filter, I have to step down from sequelize and write raw query for this that turns to be huge.

Right now I'm thinking about creating special students_expanded view for this, but I want to be sure, I'm not missing anything. Is there any way to do this using Sequelize?

Answer 1

Add an include object with the requested model and filter and set required: true on it.

The following would show all students with an absence:

Student.findAll({
    where : condition,
    limit : req.query.limit || 20,
    offset : req.query.offset || 0,
    order : req.query.order || 'id ASC'
    include: {
        model: Absense,
        required: true
    }
}))

The average grade is trickier, because you need to aggregate the grades to get the average - see Average of grouped data in column using Sequelize