dto library in copier library golang

Application scenarios:

The copier library allows the use of dto in go, which is equivalent to .net automapper

General usage: For more information, please go to githubjinzhu/copier: Copier for golang, copy value from struct to struct and more (github.com)

package main

import (
"fmt"
"github.com/jinzhu/copier"
)

typeUser struct {
Name string
Role string
Age int32
EmployeeCode int64 `copier:"EmployeeNum"` // specify field name

// Explicitly ignored in the destination struct.
Salary int
}

func (user *User) DoubleAge() int32 {
return 2 * user.Age
}

// Tags in the destination Struct provide instructions to copier.Copy to ignore
// or enforce copying and to panic or return an error if a field was not copied.
typeEmployee struct {
// Tell copier.Copy to panic if this field is not copied.
Name string `copier:"must"`

// Tell copier.Copy to return an error if this field is not copied.
Age int32 `copier:"must,nopanic"`

// Tell copier.Copy to explicitly ignore copying this field.
Salary int `copier:"-"`

DoubleAge int32
EmployeeId int64 `copier:"EmployeeNum"` // specify field name
SuperRole string
}

func (employee *Employee) Role(role string) {
employee.SuperRole = "Super " + role
}

func main() {
var (
user = User{Name: "Jinzhu", Age: 18, Role: "Admin", Salary: 200000}
users = []User{<!-- -->{Name: "Jinzhu", Age: 18, Role: "Admin", Salary: 100000}, {Name: "jinzhu 2", Age : 30, Role: "Dev", Salary: 60000}}
employee = Employee{Salary: 150000}
employees = []Employee{}
)

copier.Copy( & amp;employee, & amp;user)

fmt.Printf("%#v \\
", employee)
//Employee{
// Name: "Jinzhu", // Copy from field
// Age: 18, // Copy from field
// Salary:150000, // Copying explicitly ignored
// DoubleAge: 36, // Copy from method
// EmployeeId: 0, // Ignored
// SuperRole: "Super Admin", // Copy to method
// }

//Copy struct to slice
copier.Copy( & amp;employees, & amp;user)

fmt.Printf("%#v \\
", employees)
//[]Employee{
// {Name: "Jinzhu", Age: 18, Salary:0, DoubleAge: 36, EmployeeId: 0, SuperRole: "Super Admin"}
// }

//Copy slice to slice
employees = []Employee{}
copier.Copy( & amp;employees, & amp;users)

fmt.Printf("%#v \\
", employees)
//[]Employee{
// {Name: "Jinzhu", Age: 18, Salary:0, DoubleAge: 36, EmployeeId: 0, SuperRole: "Super Admin"},
// {Name: "jinzhu 2", Age: 30, Salary:0, DoubleAge: 60, EmployeeId: 0, SuperRole: "Super Dev"},
// }

 //Copy map to map
map1 := map[int]int{3: 6, 4: 8}
map2 := map[int32]int8{}
copier.Copy( & amp;map2, map1)

fmt.Printf("%#v \\
", map2)
// map[int32]int8{3:6, 4:8}
}

Changes in painting style:

I want to convert the user role list in the user information into []int32 slices and return them to the front end. The above method does not work at first. I cannot directly convert []UserRole into []int32. Fortunately, The workers were not discouraged or compromised, and finally solved the problem through constant testing. . .

The code is as follows

//User information struct
type Users struct {
Account string `json:"account" gorm:"unique;size:50;comment:account"`
Password string `json:"-" gorm:"comment:password" copier:"-"`
Slat string `json:"-" gorm:"comment:encryption salt" copier:"-"`
Name string `json:"name" gorm:"size:50;comment:name"`
Age uint8 `json:"age,omitempty" gorm:"size:4;comment:age"`
Gender uint8 `json:"gender,omitempty" gorm:"size:1;comment:gender"`
Phone string `json:"phone,omitempty" gorm:"size:11;comment:phone"`
Email string `json:"email,omitempty" gorm:"size:100;comment:email"`
IsActive bool `json:"isActive,omitempty" gorm:"size:1;comment: Whether to activate"`
UserRoles []UserRole `json:"roles,omitempty" gorm:"foreignKey:UserID"`
Entity
}

// The dto that needs to be mapped
typeUserDto struct {
Account string `json:"account"`
Name string `json:"name"`
Age uint8 `json:"age,omitempty"`
Gender uint8 `json:"gender,omitempty"`
Phone string `json:"phone,omitempty"`
Email string `json:"email,omitempty"`
IsActive bool `json:"isActive"`
IsDelete bool `json:"isDelete"`
CreateBy string `json:"createBy,omitempty"`
CreateTime time.Time `json:"createTime,omitempty"`
UserRoles []int32 `json:"roles,omitempty"`
}

Use copier's CopyWithOption method to customize mapping rules

// Customized TypeConverter, Users converted to Dto
var UserToDto = []copier.TypeConverter{
{
        // source type
SrcType: []domain.UserRole{},
        // mapping type
DstType: []int32{},
        // Conversion function
Fn: func(src interface{}) (interface{}, error) {
            //Type assertion, convert src to domain.UserRole
s, ok := src.([]domain.UserRole)
if !ok {
return nil, errors.New("src type not matching")
}
            //Create a slice of RoleID
r := make([]int32, 0)
for _, v := range s {
r = append(r, v.RoleID)
}
return r, nil
},
},
    { // Dto []int32 to []domain.Users
SrcType: []int32{},
DstType: []domain.UserRole{},
Fn: func(src interface{}) (interface{}, error) {
s, ok := src.([]int32)
if !ok {
return nil, errors.New("src type not matching")
}
r := make([]domain.UserRole, 0)
for _, v := range s {
r = append(r, domain.UserRole{RoleID: v})
}
return r, nil
},
},
}

// When converting, just write the following code, it is so simple and smooth

err = copier.CopyWithOption( & amp;udto, user, copier.Option{IgnoreEmpty: true, DeepCopy: true, Converters: contracts.UserToDto})

Final Results:

Welcome to give advice and discuss. .

The knowledge points of the article match the official knowledge files, and you can further learn related knowledge. Go Skill Tree Home Page Overview 4247 people are learning the system