I've two structs:
type UpdateableUser struct {
FirstName string
LastName string
Email string
Tlm float64
Dob time.Time
}
type User struct {
Id string
FirstName string
LastName string
Email string
DOB time.Time
Tlm float64
created time.Time
updated time.Time
}
Through a binder I bind request data to the updateableUser struct, therefore I might have an updateableUser with only one "real" value, like uu here:
uu := UpdateableUser{Lastname: "Smith"}
Now I want to set only the not "emtpy" values from UpdateableUser to User. Can you please give me a hint or more?
I would recommend embedding the Updateable struct into the larger struct:
type UpdateableUser struct {
FirstName string
LastName string
Email string
Tlm float64
Dob time.Time
}
type User struct {
UpdateableUser
ID string
created time.Time
updated time.Time
}
func (u *User) UpdateFrom(src *UpdateableUser) {
if src.FirstName != "" {
u.FirstName = src.FirstName
}
if src.LastName != "" {
u.LastName = src.LastName
}
// ... And other properties. Tedious, but simple and avoids Reflection
}
This allows you to use UpdateableUser as an interface to make it explicit which properties can be updated.
Related
I am trying to add a custom attribute to my Golang struct just like how I usually add custom attribute on a Laravel model using the $appends variable.
This is the code:
package models
import (
"time"
)
type Dummy struct {
ID string `json:"id" gorm:"primary_key"`
Description string `json:"description"`
Image string `json:"image"`
ImageUrl ImageUrlDummy
Number int `json:"number"`
UserId string `json:"user_id"`
User User `json:"user"`
CreatedAt time.Time `json:"created_at"`
UpdatedAt time.Time `json:"updated_at"`
}
func ImageUrlDummy() string {
return "test"
}
However, the ImageUrlDummy inside the struct does not work, it return error such as:
ImageUrlDummy (value of type func() string) is not a type
How do I achieve this same code from Laravel to Golang?
class Dummy extends Model
{
protected $appends = ['image_url'];
public function getImageUrlAttribute(){
return "this is the image url";
}
}
Please pardon me I am still learning Golang, thank you
You are not far off..
Change your struct to (remove ImageUrlDummy, fix json tag for Image):
type Dummy struct {
ID string `json:"id" gorm:"primary_key"`
Description string `json:"description"`
Image string `json:"image"`
Number int `json:"number"`
UserId string `json:"user_id"`
User User `json:"user"`
CreatedAt time.Time `json:"created_at"`
UpdatedAt time.Time `json:"updated_at"`
}
Then define a method with a receiver of type Dummy pointer
func (d *Dummy) ImageUrl() string {
return "test"
}
Example with a few more things: https://play.golang.com/p/olGSFhBgqkG
Summary
I defined a 'UserFollowing' as a 'struct' type
type UserFollowing struct {
ID string `gorm:"primaryKey;not null;unique" json:"id"`
User User `gorm:"foreignKey:ID;references:UserId"`
Followings []*User `gorm:"many2many:user_relation;joinForeignKey:UserId;JoinReferences:following_id"`
}
Where type 'User' is defined as
type User struct {
Email string `gorm:"size:100;not null;unique" json:"email"`
Password string `gorm:"size:60;not null" json:"password,omitempty"`
CreatedAt time.Time `gorm:"default:current_timestamp()" json:"created_at"`
UpdatedAt time.Time `gorm:"default:current_timestamp()" json:"updated_at"`
Verified bool `gorm:"default:false" json:"verified"`
AToken string `gorm:"size:100;not null;unique" json:"accessToken"`
RToken string `gorm:"size:100;not null;unique" json:"refreshToken"`
YouAreFollowing bool `json:"youAreFollowing"`
Username string `json:"username"`
Online bool `json:"online"`
NumFollowing uint64 `json:"numFollowing"`
NumFollowers uint64 `json:"numFollowers"`
LastOnline time.Time `gorm:"default:current_timestamp()" json:"lastOnline"`
UserId string `gorm:"primaryKey;not null;unique" json:"userid"`
FollowsYou bool `json:"followsYou"`
BotOwnerId string `json:"botOwnerId"`
Contributions uint64 `json:"contributions"`
Staff bool `json:"staff"`
DisplayName string `gorm:"size:20" json:"displayName"`
CurrentRoomId string `json:"currentRoomId"`
CurrentRoom Room `json:"currentRoom"`
Bio string `gorm:"size:250" json:"bio"`
Avatar string `gorm:"size:100" json:"avatarUrl"`
BannerUrl string `json:"bannerUrl"`
WhisperPrivacySetting string `json:"whisperPrivacySetting"`
Room_Permissions RoomPermissions `json:"roomPermissions"`
}
I tried to append 'User' type elements to the 'Followings' field by doing the following:
for i, _ := range users {
...
userfollowings[i].ID = users[i].UserId
userfollowings[i].Followings = append(userfollowings[i].Followings, users[i])
...
}
Error
cannot use users[i] (type models.User) as type *models.User in append
Unsuccessful Attempt
*userfollowings[i].Followings = append(*userfollowings[i].Followings, users[i])
References consulted
difference-using-pointer-in-struct-fields
Any suggestions on how to solve this problem?
You should use address of the structure instead of direct value if you want to store pointers []*User.
Try to visit this page and run this code:
package main
import "fmt"
type User struct {
UserId string
}
type UserFollowing struct {
ID string
Followings []*User
}
var (
users = []User{{"user-1"}, {"user-2"}, {"user-3"}}
userFollowings = make([]UserFollowing, len(users))
)
func main() {
for i, _ := range users {
// ...
userFollowings[i].ID = users[i].UserId
userFollowings[i].Followings = append(userFollowings[i].Followings, &users[i])
// ...
}
fmt.Println("%#v", userFollowings)
}
I'm trying to follow Gorm's documentation to create a generated field, defined by a function:
type Foo struct {
ID int64 `json:"id"`
AmountOfBars string `json:"amount_of_bars" gorm:"default:amount_of_bars()"`
}
type RelatedBar struct {
FooId int64 `json:"foo_id"`
}
However, I don't understand where and how to define amount_of_bars, so I'll be able to return the amount of the RelatedBar related rows.
You don't define such a function in Go, you define it in your database via CREATE FUNCTION. See https://www.postgresql.org/docs/9.1/sql-createfunction.html.
type User struct {
ID int `json:"id" gorm:"autoIncrement; primaryKey"`
Username string `json:"username" `
FirstName string `json:"first_name" `
LastName string `json:"last_name" `
FullName string `json:"full_name" `
Name string `json:"name" `
AvatarURL string `json:"avatar_url" gorm:"default:'http://www.google/.com'" `
CreatedAt int // Set to current time if it is zero on creating
UpdatedAt int // Set to current unix seconds on updating or if it is zero on creating
Deleted gorm.DeletedAt
}
I am playing with gin-gonic+sqlx. Now I wonder what is the best way to dynamically bind database records to the struct?
Saying I have a struct and a query like this.
type Project struct {
ID string `db:"id"`
CreatedAt time.Time `db:"created_at"`
UpdatedAt time.Time `db:"updated_at"`
DeletedAt NullTime `db:"deleted_at"`
Name string
Status string
OpenDate NullTime `db:"open_date"`
Number uint
}
func (p Project) List() ([]Project, error) {
var pp []Project
err := db.Select(&pp, "SELECT * FROM Project")
return pp, err
}
Now I want to add field-level permissions to this struct. For example, an admin can view and edit all fields; User A can view CreatedAt and Name; User B can view and edit Name Status and view Number.
I was writing multiply structs for each use case, but obviously, I did choose the silliest way.
The other method I can think of is to implement Struct Tag. Am I on the right track or is there a better way to do this?
We can create multiple structs and embed among each other.
Example:
type ProjectSummary struct {
ID string `db:"id"`
Name string
}
type ProjectUser struct {
ProjectSummary
CreatedAt time.Time `db:"created_at"`
}
type ProjectSupport struct {
ProjectSummary
Status string
Number uint
}
type ProjectAdmin struct {
ProjectSupport
CreatedAt time.Time `db:"created_at"`
UpdatedAt time.Time `db:"updated_at"`
DeletedAt NullTime `db:"deleted_at"`
OpenDate NullTime `db:"open_date"`
}
I want to set the Coins struct's Address as a foreign key of Accounts struct's address, how to set it in beego orm?
type Coins struct {
Id int `orm:"auto"`
Address string `orm:"rel(fk);on_delete(cascade);on_update(cascade);index" json:"address"`
Symbol string `json:"symbol"`
Amount float64 `orm:"digits(64);decimals(6)" json:"amount"`
CreatedAt time.Time `orm:"auto_now_add;type(datetime)"`
UpdatedAt time.Time `orm:"auto_now_add;type(datetime)"`
}
type Accounts struct {
Id int `orm:"auto"`
Address string `orm:"index;unique" json:"address"`
Type string `json:"type"`
}
See, if this works:
type Coins struct {
Id int `orm:"auto"`
Accouts *Accounts `orm:"rel(fk)"`
Address string `orm:"pk;auto;on_delete(cascade);on_update(cascade);index" json:"address"`
Symbol string `json:"symbol"`
Amount float64 `orm:"digits(64);decimals(6)" json:"amount"`
CreatedAt time.Time `orm:"auto_now_add;type(datetime)"`
UpdatedAt time.Time `orm:"auto_now_add;type(datetime)"`
}
type Accounts struct {
Id int `orm:"pk;auto"`
Address string `orm:"index;unique" json:"address"`
Type string `json:"type"`
}