jirfag/go-queryset

package gorm4

import (
    "time"

    "github.com/jinzhu/gorm"
)

func getGormDB() *gorm.DB {
    db, _ := gorm.Open("mysql",
        "user:password@/dbname?charset=utf8&parseTime=True&loc=Local")
    return db
}

//go:generate goqueryset -in gorm4.go

// User struct represents user model.
// gen:qs
type User struct {
    gorm.Model
    Rating      int
    RatingMarks int
}

func getTodayBegin() time.Time {
    year, month, day := time.Now().Date()
    return time.Date(year, month, day, 0, 0, 0, 0, time.Now().Location())
}

// WithMaxRating is our defined on UserQuerySet method, that selects
// users with max rating.
// UserQuerySet is an autogenerated struct with a lot of typesafe methods.
// We can define any methods on it because it's in the same package
func (qs UserQuerySet) WithMaxRating(minMarks int) UserQuerySet {
    return qs.RatingMarksGte(minMarks).OrderDescByRating()
}

// RegisteredToday returns only users registered today
func (qs UserQuerySet) RegisteredToday() UserQuerySet {
    // autogenerated typesafe method CreatedAtGte(time.Time)
    return qs.CreatedAtGte(getTodayBegin())
}

// now we can parametrize it
const minRatingMarks = 10

// GetUsersWithMaxRating returns limit users with max rating
func GetUsersWithMaxRating(limit int) ([]User, error) {
    var users []User
    err := NewUserQuerySet(getGormDB()).
        WithMaxRating(minRatingMarks). // reuse our method
        Limit(limit).                  // autogenerated typesafe method Limit(int)
        All(&users)                    // autogenerated typesafe method All(*[]User)
    if err != nil {
        return nil, err
    }
    return users, nil
}

// GetUsersRegisteredToday returns limit users registered today
func GetUsersRegisteredToday(limit int) ([]User, error) {
    var users []User
    err := NewUserQuerySet(getGormDB()).
        RegisteredToday(). // reuse our method
        Limit(limit).      // autogenerated typesafe method Limit(int)
        All(&users)        // autogenerated typesafe method All(*[]User)
    if err != nil {
        return nil, err
    }
    return users, nil
}

// GetUsersRegisteredTodayWithMaxRating returns limit users
// registered today and with max rating
func GetUsersRegisteredTodayWithMaxRating(limit int) ([]User, error) {
    var users []User
    err := NewUserQuerySet(getGormDB()).
        RegisteredToday().             // reuse our method
        WithMaxRating(minRatingMarks). // reuse our method
        Limit(limit).
        All(&users) // autogenerated typesafe method All(*[]User)
    if err != nil {
        return nil, err
    }
    return users, nil
}