I have an issue understanding how to fetch related information using gorm. This is the first time ever I'm using an ORM actively.
I'm trying to get all devices that a specific user id has access to. With the current function I get all devices, not only the device belonging to the actual user id, and it also includes the list of users that the device belongs to, which is information i really don't need at this point.
Is there a way to Get the devices that the user has access to using the user_devices join table using gorm, or is this something i should create a custom query in order to achieve what I want?
Thank you.
type User struct {
ID uint
Name string
Email string
Age uint8
Birthday time.Time
Password string
ActivatedAt time.Time
OrgID uint
Org Org
Devices []Device `gorm:"many2many:user_devices"`
CreatedAt time.Time
UpdatedAt time.Time
}
type Device struct {
ID uint
Name string
Hwaddr string
OrgID uint
PublicIP uint
Org Org
Users []User `gorm:"many2many:user_devices"`
DeviceType string
Identity string
LastPolledAt time.Time
CreatedAt time.Time
UpdatedAt time.Time
}
func (u *Device) FindAllDevicesByUid(db *gorm.DB, user *User) (*[]Device, error) {
var err error
devices := []Device{}
err = db.Debug().Preload("Users", "user_id = ?", user.ID).Find(&devices).Error
if err != nil {
return &[]Device{}, err
}
return &devices, err
}
Result:
{
"ID": 4,
"Name": "Test 4",
"Hwaddr": "00:00:00:00:00:04",
"OrgID": 1,
"PublicIP": 0,
"Org": {
"Id": 0,
"Name": "",
"Users": null,
"CreatedAt": "0001-01-01T00:00:00Z",
"UpdatedAt": "0001-01-01T00:00:00Z"
},
"Users": [
{
"ID": 1,
"Name": "Jan Astrup",
"Email": "[email protected]",
"Age": 0,
"Birthday": "0001-01-01T00:00:00Z",
"ActivatedAt": "2022-04-24T15:48:40 02:00",
"OrgID": 1,
"Org": {
"Id": 0,
"Name": "",
"Users": null,
"CreatedAt": "0001-01-01T00:00:00Z",
"UpdatedAt": "0001-01-01T00:00:00Z"
},
"Devices": null,
"CreatedAt": "2022-04-24T15:48:40 02:00",
"UpdatedAt": "2022-04-24T15:48:40 02:00"
}
],
"DeviceType": "Router",
"Identity": "M1923 4",
"LastPolledAt": "0001-01-01T00:00:00Z",
"CreatedAt": "2022-04-24T15:17:30 02:00",
"UpdatedAt": "2022-04-24T15:17:30 02:00"
}
CodePudding user response:
To load just the devices for a specific user, you can use the Joins
function to join tables user_devices
and devices
.
devices := []Device{}
err = db.Debug().Joins("JOIN user_devices ud ON ud.device_id = devices.id").Where("ud.user_id = ?", user.ID).Find(&devices).Error
Apart from this, you can always load the user and preload its devices:
u := User{}
err = db.Debug().Preload("Devices").First(&u, user.ID).Error
Then, you can use u.Devices
to return the user's devices, but I think this approach executes two queries to get the user's devices.