Why is Go json.Marshal rejecting these struct tags? What is proper syntax for json tags? [duplicate]

Question

I am trying to use json.Marshal but it refuses to accept my struct tags.

What am I doing wrong?

Here is the source code for "marshal.go"

https://play.golang.org/p/eFe03_89Ly9

package main  import (     "encoding/json"     "fmt" )  type Person struct {     Name string `json: "name"`     Age  int    `json: "age"` }  func main() {     p := Person{Name: "Alice", Age: 29}     bytes, _ := json.Marshal(p)     fmt.Println("JSON = ", string(bytes)) } 

I get these error messages from "go vet marshal.go"

./marshal.go:9: struct field tag `json: "name"` not compatible with reflect.StructTag.Get: bad syntax for struct tag value ./marshal.go:10: struct field tag `json: "age"` not compatible with reflect.StructTag.Get: bad syntax for struct tag value 

I get this output when I run the program.

% ./marshal JSON =  {"Name":"Alice","Age":29} 

Notice the field names match the Go structure and ignore the json tags.

What am I missing?

Answer 1

Oh my goodness! I just figured it out. There is no space allowed between json: and the field name "name".

The "go vet" error message ("bad syntax") is remarkably unhelpful.

The following code works. Can you see the difference?

package main  import (     "encoding/json"     "fmt" )  type Person struct {     Name string `json:"name"`     Age  int    `json:"age"` }  func main() {     p := Person{Name: "Alice", Age: 29}     bytes, _ := json.Marshal(p)     fmt.Println("JSON = ", string(bytes)) }