[ 常見問題 ] How to print struct variables in console?

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Question
How can I print (in the console) the Id, Title, Name, etc. of this struct in Golang?

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1. type Project struct {  
2.     Id      int64   `json:"project_id"`  
3.     Title   string  `json:"title"`  
4.     Name    string  `json:"name"`  
5.     Data    Data    `json:"data"`  
6.     Commits Commits `json:"commits"`  
7. }  

HowTo
To print the name of the fields in a struct:

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1. fmt.Printf("%+v\n", yourProject)  

From the fmt package:

when printing structs, the plus flag (%+v) adds field names

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:

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1. type Response2 struct {  
2.   Page   int      `json:"page"`  
3.   Fruits []string `json:"fruits"`  
4. }  
5.   
6. res2D := &Response2{  
7.     Page:   1,  
8.     Fruits: []string{"apple", "peach", "pear"}}  
9. res2B, _ := json.Marshal(res2D)  
10. 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:

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1. type T struct {  
2.     A int  
3.     B string  
4. }  
5.   
6. t := T{23, "skidoo"}  
7. s := reflect.ValueOf(&t).Elem()  
8. typeOfT := s.Type()  
9.   
10. for i := 0; i < s.NumField(); i++ {  
11.     f := s.Field(i)  
12.     fmt.Printf("%d: %s %s = %v\n", i,  
13.         typeOfT.Field(i).Name, f.Type(), f.Interface())  
14. }