如何在忽略空字符串的情况下连接结构的字符串字段？

Question

I am really new to Go, so want some advice. I have a struct:

type Employee struct {
    Name        string
    Designation string
    Department  string
    Salary      int
    Email       string
}

I want to concatenate the string fields into a type of employee description. So that, I can say: toString(employee) and get:

John Smith Manager Sales [e-mail]

I tried to fetch each field, check if they are empty and put them in a slice and join them at the end

employeeDescArr := make([]string, 0, 4)
if strings.TrimSpace(value) != "" {
    append(employee.GetName(), value)
}...
return strings.Join(employeeDescArr[:], " ")

I think this method is very verbose and shows lack of Go skills. Is it better to use a string Builder instead? Is there a way to iterate through all fields of a struct in a Reflection way and join them?

Answer 1

Loop through the string fields and collect non-empty strings. Join the fields.

func (e *Employee) String() string {
    var parts []string
    for _, s := range []string{e.Name, e.Designation, e.Department, e.Email} {
        if strings.TrimSpace(s) != "" {
            parts = append(parts, s)
        }
    }
    return strings.Join(parts, " ")
}

Because the strings.Join function is implemented using strings.Builder, there's no benefit to replacing strings.Join with application code that uses strings.Builder.

Here's how to use reflect to avoid listing the fields in the string function:

var stringType = reflect.TypeOf("")

func (e *Employee) String() string {
    v := reflect.ValueOf(e).Elem()
    var parts []string
    for i := 0; i < v.NumField(); i++ {
        f := v.Field(i)
        if f.Type() == stringType {
            s := f.String()
            if strings.TrimSpace(s) != "" {
                parts = append(parts, s)
            }
        }
    }
    return strings.Join(parts, " ")
}

If you want to include all fields (include non-strings and empty strings), then you can fmt.Sprint(e) to get a string. See https://play.golang.org/p/yntZxQ-Xs6C.