reflect.FieldByIndex() Function in Golang with Examples
Go language provides inbuilt support implementation of run-time reflection and allowing a program to manipulate objects with arbitrary types with the help of reflect package. The reflect.FieldByIndex() Function in Golang is used to get the nested field corresponding to index. To access this function, one needs to imports the reflect package in the program.
Syntax:
func (v Value) FieldByIndex(index []int) ValueParameters: This function accept only single parameters.
- index : This parameter is the []int type.
Return Value: This function returns the nested field corresponding to index.
Below examples illustrate the use of the above method in Golang:
Example 1:
// Golang program to illustrate // reflect.FieldByIndex() Function package main import ( "fmt" "reflect" ) // Main function func main() { tt:= reflect.StructOf([]reflect.StructField{ { Name: "Height" , Type: reflect.TypeOf(0.0), Tag: `json: "height" `, }, { Name: "Name" , Type: reflect.TypeOf( "abc" ), Tag: `json: "name" `, }, }) // use of FieldByIndex() method fmt.Println(tt.FieldByIndex([] int {0})) } |
Output:
{Height float64 json:"height" 0 [0] false}
Example 2:
// Golang program to illustrate // reflect.FieldByIndex() Function package main import ( "fmt" "reflect" ) type User struct { Id int Name string Age int } type Manager struct { User Title string } // Main function func main() { m := Manager{User: User{1, "Jack" , 12}, Title: "123" } t := reflect.TypeOf(m) fmt.Printf( "%#v\n" , t.Field(0)) fmt.Printf( "%#v \n" , t.Field(1)) // use of FieldByIndex() method fmt.Printf( "%#v \n" , t.FieldByIndex([] int {0, 0})) fmt.Printf( "%#v \n" , t.FieldByIndex([] int {0, 1})) fmt.Printf( "%#v \n" , t.FieldByIndex([] int {0, 2})) } |
Output:
reflect.StructField{Name:”User”, PkgPath:””, Type:(*reflect.rtype)(0x4b1480), Tag:””, Offset:0x0, Index:[]int{0}, Anonymous:true}
reflect.StructField{Name:”Title”, PkgPath:””, Type:(*reflect.rtype)(0x4a1c20), Tag:””, Offset:0x20, Index:[]int{1}, Anonymous:false}
reflect.StructField{Name:”Id”, PkgPath:””, Type:(*reflect.rtype)(0x4a14e0), Tag:””, Offset:0x0, Index:[]int{0}, Anonymous:false}
reflect.StructField{Name:”Name”, PkgPath:””, Type:(*reflect.rtype)(0x4a1c20), Tag:””, Offset:0x8, Index:[]int{1}, Anonymous:false}
reflect.StructField{Name:”Age”, PkgPath:””, Type:(*reflect.rtype)(0x4a14e0), Tag:””, Offset:0x18, Index:[]int{2}, Anonymous:false}
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