show json array inside of a json object using gorm - json

Question

I'm trying to use gorm for my queries. I have a model called users just like this:
type Users struct {
gorm.Model
ID uint `gorm:"autoIncrement;unique" json:"id"`
PhoneNumber string `gorm:"primaryKey" json:"phone_number"`
Name string `gorm:"default:dear user" json:"name"`
Rank uint `json:"rank"`
Score uint `json:"score"`
Image string `json:"image"`
Email string `json:"email"`
Address string `json:"address"`
Birthday string `json:"birthday"`
Biography string `json:"biography"`
}
and another model which represents the courses that the user has purchased.
type UserCourse struct {
CourseID uint `gorm:"primaryKey" json:"course_id"`
UserPhoneNumber string `gorm:"primaryKey" json:"user_phone_number"`
Progress uint `json:"progress"`
CreatedAt time.Time
UpdatedAt time.Time
}
now I am looking for a way to return top 100 users based on their score with the courses they have purchased. in the other word, the below JSON object is desirable:
{
"users":[
{
"id":1,
"phoneNumber":"99999999",
"name":"test",
"rank":1,
"score":123456789,
"image":"http://...",
"email":"test#test.com",
"address":"test",
"birthday":"2021-01-01",
"biography":"test here",
"courses": [
{
"course_id":1,
"user_phone_number":"99999999",
"progress": 53,
"created_at": "2021-01-01",
"updated_at": "2021-01-01",
} ,
{
"course_id":2,
"user_phone_number":"99999999",
"progress":100,
"created_at":"2021-02-01",
"updated_at":"2021-03-01",
}
]
}
]
}
I know I have to use the below query to get top 100 users:
database.myDatabase.Order("rank asc").Limit(100).Find(users)
but unfortunately, I have no idea how to write the gorm suitable for the mentioned output.

Answer 1

If you extend your Users model as such:
type Users struct {
gorm.Model
ID uint `gorm:"autoIncrement;unique" json:"id"`
PhoneNumber string `gorm:"primaryKey" json:"phone_number"`
Name string `gorm:"default:dear user" json:"name"`
Rank uint `json:"rank"`
Score uint `json:"score"`
Image string `json:"image"`
Email string `json:"email"`
Address string `json:"address"`
Birthday string `json:"birthday"`
Biography string `json:"biography"`
Courses []*UserCourse `gorm:"foreignKey:UserPhoneNumber;references:PhoneNumber" json:"courses"`
}
you can then preload the courses into the user struct by using:
database.myDatabase.Preload("Courses").Order("rank asc").Limit(100).Find(users)