How to print struct variables in console?
my 2cents would be to use json.MarshalIndent
-- surprised this isn't suggested, as it is the most straightforward. for example:
func prettyPrint(i interface{}) string {
s, _ := json.MarshalIndent(i, "", "\t")
return string(s)
}
no external deps and results in nicely formatted output.
To print the name of the fields in a struct:
fmt.Printf("%+v\n", yourProject)
From the fmt
package:
when printing structs, the plus flag (
%+v
) adds field names
That supposes you have an instance of Project (in 'yourProject
')
The article JSON and Go will give more details on how to retrieve the values from a JSON struct.
This Go by example page provides another technique:
type Response2 struct {
Page int `json:"page"`
Fruits []string `json:"fruits"`
}
res2D := &Response2{
Page: 1,
Fruits: []string{"apple", "peach", "pear"}}
res2B, _ := json.Marshal(res2D)
fmt.Println(string(res2B))
That would print:
{"page":1,"fruits":["apple","peach","pear"]}
If you don't have any instance, then you need to use reflection to display the name of the field of a given struct, as in this example.
type T struct {
A int
B string
}
t := T{23, "skidoo"}
s := reflect.ValueOf(&t).Elem()
typeOfT := s.Type()
for i := 0; i < s.NumField(); i++ {
f := s.Field(i)
fmt.Printf("%d: %s %s = %v\n", i,
typeOfT.Field(i).Name, f.Type(), f.Interface())
}
I want to recommend go-spew, which according to their github "Implements a deep pretty printer for Go data structures to aid in debugging"
go get -u github.com/davecgh/go-spew/spew
usage example:
package main
import (
"github.com/davecgh/go-spew/spew"
)
type Project struct {
Id int64 `json:"project_id"`
Title string `json:"title"`
Name string `json:"name"`
Data string `json:"data"`
Commits string `json:"commits"`
}
func main() {
o := Project{Name: "hello", Title: "world"}
spew.Dump(o)
}
output:
(main.Project) {
Id: (int64) 0,
Title: (string) (len=5) "world",
Name: (string) (len=5) "hello",
Data: (string) "",
Commits: (string) ""
}
I think it would be better to implement a custom stringer if you want some kind of formatted output of a struct
for example
package main
import "fmt"
type Project struct {
Id int64 `json:"project_id"`
Title string `json:"title"`
Name string `json:"name"`
}
func (p Project) String() string {
return fmt.Sprintf("{Id:%d, Title:%s, Name:%s}", p.Id, p.Title, p.Name)
}
func main() {
o := Project{Id: 4, Name: "hello", Title: "world"}
fmt.Printf("%+v\n", o)
}