我正尝试通过GORM发出特定请求。
这是我使用的表格：
+-------------------+
| Tables |
+-------------------+
| locations |
| shops |
| shops_tags |
| tags |
+-------------------+
位置表
+------------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+------------+------------------+------+-----+---------+----------------+
| id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| shop_id | bigint(20) | YES | | NULL | |
| lat | decimal(10,8) | YES | | NULL | |
| lng | decimal(11,8) | YES | | NULL | |
+------------+------------------+------+-----+---------+----------------+
位置模型
type Location struct {
gorm.Model
ShopID int64
Shop Shop
Lat float64 `gorm:"type:decimal(10,8)"`
Lng float64 `gorm:"type:decimal(11,8)"`
}
商店表
+-------------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+------------------+------+-----+---------+----------------+
| id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| name | varchar(180) | YES | UNI | NULL | |
| active | tinyint(1) | YES | | 1 | |
+-------------+------------------+------+-----+---------+----------------+
商店型号
type Shop struct {
gorm.Model
Name string `json:"name" gorm:"type:varchar(180);unique_index"`
Active int `json:"active" gorm:"type:tinyint(1);default:1"`
Tags []*Tag `json:"tags" gorm:"many2many:shops_tags;"`
Locations []Location `json:"locations" gorm:"locations"`
}
标记模型
type Tag struct {
gorm.Model
Name string `json:"name" gorm:"type:varchar(180)"`
Shops []*Shop `json:"shops" gorm:"many2many:shops_tags;"`
}
处理程序，以JSON返回查询
func GetShops(c echo.Context) error {
db := db.DbManager()
// Get POST data (name lat and lng)
type geo struct {
Lat string `json:"lat" form:"lat" query:"lat"`
Lng string `json:"lng" form:"lng" query:"lng"`
}
// Bind request body
g := new(geo)
if err := c.Bind(g); err != nil {
return c.JSON(http.StatusForbidden, err)
}
shops := []model.Shop{}
// Totally disordered attempt of a query with `go-gorm` to display the list of nearby shops, sorted by the distance between us.
db.Preload("Locations", func(db *gorm.DB) *gorm.DB {
// How here use g.Lat and g.Lng for this request
return db.Order("locations.id DESC").Limit(1)
}).Preload("Tag").Find(&shops)
// Json
return c.JSON(http.StatusOK, echo.Map{
"shops": &shops,
})
}
因此我们有商店，其中有位置，我们想在位置 15公里以内显示商店 。只有最后一个位置是有用的，这就是为什么我们将结果按降序限制为1。
编辑
感谢@Rick James建议我改写我的问题，这是MYSQL中的查询，如何将其调整为go-gorm：
SELECT
shops.id,
shops.name, (
(
6371.04 * ACOS(
(
(
COS(
(
(
PI() / 2
) - RADIANS(
(90 - locations.lat)
)
)
) * COS(
PI() / 2 - RADIANS(90 - -33.73788500)
) * COS(
(
RADIANS(locations.lng) - RADIANS('151.23526000')
)
)
) + (
SIN(
(
(
PI() / 2
) - RADIANS(
(90 - locations.lat)
)
)
) * SIN(
(
(
PI() / 2
) - RADIANS(90 - -33.73788500)
)
)
)
)
)
)
) AS 'distance',
locations.id AS 'location_id',
locations.shop_id,
locations.lat,
locations.lng,
locations.created_at
FROM
shops
INNER JOIN locations ON(
locations.created_at >= '2017-12-13'
AND(
(
6371.04 * ACOS(
(
(
COS(
(
(
PI() / 2
) - RADIANS(
(90 - locations.lat)
)
)
) * COS(
PI() / 2 - RADIANS(90 - -33.73788500)
) * COS(
(
RADIANS(locations.lng) - RADIANS('151.23526000')
)
)
) + (
SIN(
(
(
PI() / 2
) - RADIANS(
(90 - locations.lat)
)
)
) * SIN(
(
(
PI() / 2
) - RADIANS(90 - -33.73788500)
)
)
)
)
)
)
) < '500'
AND shops.id = (locations.shop_id)
)
WHERE
shops.active = 1
GROUP BY
shops.id
ORDER BY
distance ASC
LIMIT
100
答案 0 :(得分：1)
看着查询，我一定会手工制作这个，而不依赖任何ORM来执行查询。请参考在gorm数据库实例ref上使用Exec方法。
但是... 要使用像gorm这样的ORM，可以使用gorm的SQL-Builder。这是一个应该提供指导的例子。请注意，这是针对SQLite数据库的，而不是针对MYSQL的，因此所使用的功能不存在。我们主要关注构建查询。
package main
import (
"fmt"
"time"
"github.com/jinzhu/gorm"
_ "github.com/jinzhu/gorm/dialects/sqlite"
)
const (
layoutISO = "2006-01-02"
)
type Shop struct {
gorm.Model
Name string `json:"name" gorm:"type:varchar(180);unique_index"`
Active int `json:"active" gorm:"type:tinyint(1);default:1"`
Tags []Tag `json:"tags" gorm:"many2many:shops_tags;"`
Locations []Location `json:"locations" gorm:"locations"`
}
type Tag struct {
gorm.Model
Name string `json:"name" gorm:"type:varchar(180)"`
Shops []Shop `json:"shops" gorm:"many2many:shops_tags;"`
}
type Location struct {
gorm.Model
ShopID int64
Shop Shop
Lat float64 `gorm:"type:decimal(10,8)"`
Lng float64 `gorm:"type:decimal(11,8)"`
}
// Get POST data (name lat and lng)
type geo struct {
Lat float64 `json:"lat" form:"lat" query:"lat"`
Lng float64 `json:"lng" form:"lng" query:"lng"`
}
var distance_calculation = `
(
(
6371.04 * ACOS(((COS(((PI() / 2) - RADIANS((90 - locations.lat)))) *
COS(PI() / 2 - RADIANS(90 - ?)) *
COS((RADIANS(locations.lng) - RADIANS(?))))
+ (SIN(((PI() / 2) - RADIANS((90 - locations.lat)))) *
SIN(((PI() / 2) - RADIANS(90 - ?))))))
)
)`
func main() {
db, err := gorm.Open("sqlite3", "test.db")
if err != nil {
panic("failed to connect database")
}
defer db.Close()
// Enable Logger, show detailed log
db.LogMode(true)
// Migrate the schema
db.AutoMigrate(&Shop{})
db.AutoMigrate(&Tag{})
db.AutoMigrate(&Location{})
g := new(geo)
g.Lat = -33.73788500
g.Lng = 151.23526000
type Result struct {
ID uint
Name string
Distance int
LocationID uint
ShopID uint
Lat float64
Lng float64
CreatedAt time.Time
}
date, _ := time.Parse(layoutISO, "2017-12-13")
var t []Result
err = db.Table("Shops").
Select("shops.id, shops.name, locations.id AS 'location_id', locations.shop_id, locations.lat, locations.lng, locations.created_at, "+
distance_calculation+" as distance\n", g.Lat, g.Lng, g.Lat).
Joins("inner join locations on shops.id = locations.shop_id\n").
Where(&Shop{Active: 1}).
Where("locations.created_at >= CAST(strftime('%s', ?) AS INT) * 1000", date).
Where(distance_calculation + " < ?", g.Lat, g.Lng, g.Lat, 500).
Group("\nshops.id\n").
Order("locations.id DESC\n").
Limit(100).Scan(&t).Error
if err != nil {
panic(err)
}
fmt.Printf("%+v\n", t)
}
使用SQL Builder构建的查询
(C:/Users/fakename/source/stackoverflow/go/geo-go-gorm/main.go:97)
[2019-10-31 15:36:37] [1.00ms] SELECT shops.id, shops.name, locations.id AS 'location_id', locations.shop_id, locations.lat, locations.lng, locations.created_at,
(
(
6371.04 * ACOS(((COS(((PI() / 2) - RADIANS((90 - locations.lat)))) *
COS(PI() / 2 - RADIANS(90 - -33.737885)) *
COS((RADIANS(locations.lng) - RADIANS(151.23526))))
+ (SIN(((PI() / 2) - RADIANS((90 - locations.lat)))) *
SIN(((PI() / 2) - RADIANS(90 - -33.737885))))))
)
) as distance
FROM "Shops" inner join locations on shops.id = locations.shop_id
WHERE ("shops"."active" = 1) AND (locations.created_at >= CAST(strftime('%s', '2017-12-13 00:00:00') AS INT) * 1000) AND (
(
(
6371.04 * ACOS(((COS(((PI() / 2) - RADIANS((90 - locations.lat)))) *
COS(PI() / 2 - RADIANS(90 - -33.737885)) *
COS((RADIANS(locations.lng) - RADIANS(151.23526))))
+ (SIN(((PI() / 2) - RADIANS((90 - locations.lat)))) *
SIN(((PI() / 2) - RADIANS(90 - -33.737885))))))
)
) < 500
) GROUP BY shops.id
ORDER BY locations.id DESC
LIMIT 100