How to check custom types using reflection in Golang?

Use reflection to check custom types in Go: import the "reflect" package. Use reflect.ValueOf() to get the value of a type. Use reflect.TypeOf() to get the type's reflect.Type. Use NumField() and Field() to get fields. Use NumMethod() and Method() to obtain public methods. Use FieldByName() to get the field value. Use Call() to call public methods.

How to use reflection to check custom types in Golang

Reflection is a powerful feature in the Golang standard library , which allows programs to inspect and manipulate arbitrary data types at runtime. Using reflection, you can inspect a custom type's values, methods, and fields, and even create and modify the type itself.

Reflection Basics

The first step in using reflection is to reference the reflect package:

import "reflect"

Values ​​of type can be passedreflect.ValueOf() Function gets:

v := reflect.ValueOf(yourValue)

reflect.Type type represents a Go type. You can use the reflect.TypeOf() function to get the reflect.Type of a type:

typ := reflect.TypeOf(YourType{})

Check custom types

Get the field

Use the NumField() and Field() methods to get the type of field:

for i := 0; i < typ.NumField(); i++ {
  fmt.Println(typ.Field(i).Name)
}

Getting methods

Use the NumMethod() and Method() methods to get the public methods of the type:

for i := 0; i < typ.NumMethod(); i++ {
  fmt.Println(typ.Method(i).Name)
}

Check the type value

Get the field value

Use the FieldByName() method to get the field value of the type:

value := v.FieldByName("FieldName").Interface()

Call method

Use the Call() method to call the public method of the type:

result := v.MethodByName("MethodName").Call([]reflect.Value{reflect.ValueOf(arg1), reflect.ValueOf(arg2)})

Practical case

The following is a simple example of using reflection to inspect a custom type:

type MyType struct {
  Name string
  Age  int
}

myType := MyType{
  Name: "John Doe",
  Age:  30,
}

// 检查类型元信息
fmt.Println("Type:", reflect.TypeOf(myType))

// 检查名称字段
fmt.Println("Name Field:", reflect.ValueOf(myType).FieldByName("Name").String())

// 调用 ToString 方法
result := reflect.ValueOf(myType).MethodByName("ToString").Call([]reflect.Value{})
fmt.Println("ToString Result:", string(result[0].Bytes()))

This example shows how to obtain the metainformation of the type, access field values, and call methods.

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