Assign value to field in struct if empty - go

Question

I have a struct defined
type data struct {
invitecode string
fname string
lname string
}
which I populate from retrieving form data after parsing
...
r.ParseForm()
new user := &data{
invitecode: r.FormValue("invitecode"),
fname: r.FormValue("fname")
lname: r.FormValue("lname")
}
I did like to check if the invitecode field obtained from the form is empty and if so, populate it by calling a function but if it is not, to populate it with the retrieved value (invitecode: if newUser.invitecode == "" {"Mr"} else {lnames.title},). I understand go doesn't have a tenary operator which I thought of using and reading the questions here, here, here & here implies using an if else statement but I can't seem to get it to work. Preferable, I am looking for a solution that check's while assigning a new variable. Trying the code below doesn't seem to work. Any help would be appreciated.
package main
import (
"fmt"
)
type data struct {
invitecode string
fname string
lname string
}
func main() {
var user data
newUser := map[string]string{"invitecode": "", "fname": "Dude", "lname": "Did"}
user = &data{
invitecode: if newUser.invitecode == "" {"Mr"} else {lnames.title},
fname: newUser.fname,
lname: newUser.lname,
}
fmt.Println(user)
}

Answer 1

You cannot use an if ... else statement inline like you would a ternary operator (or if/else statements) in other languages, you must simply do it procedurally:
user := &data{ /* ... */ }
if user.invitecode == "" {
user.invitecode = "Mr"
} else {
user.invitecode = lnames.title
}

Answer 2

Go does not have ternaries, nor can you do an inline if like you've shown in the code. You will have to do a normal if block:
user = &data{}
if newUser.inviteCode == "" {
user.invitecode = "Mr"
} else {
user.invitecode = lnames.title
}
And so on. You could extract this into a function:
func coalesce(args ...string) string {
for _,str := range args {
if str != "" {
return str
}
}
return ""
}
And use it like so:
user.invitecode = coalesce(lnames.title, "Mr")
Of course, if you deal with multiple types (not just strings), you'll need one such function for each type.