isset in golang!

[amir-taghavi]

hi

 in php we can used isset function to check which variable is set or not set 

<?php

...

if(isset($_POST["name"])){

...

}

...

?>

how is it in golang?

[Matthew Kane]

If you're looking to see if a key exists in a map, like the PHP code
here is doing, use this form of map indexing:

if name, ok := yourmap["name"]; ok {
// name is the string that was stored in the map
} else {
// name is the zero value of whatever values are stored in the map

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[amir-taghavi]

please see the follow code 

func Printuser(w http.ResponseWriter,r *http.Request){

if user,ok:=r.FormValue("user");ok{

user := r.FormValue("name")

pass := r.FormValue("pass")

fmt.Fprintf(w,"Hi %s - %s",user,pass)

}

}

i don't underestand which how isset r.FormValue("user") please help me

[cm...@golang.org]

First of all, does that code even compile? FormValue (http://godoc.org/net/http#Request.FormValue) only returns a string and that string will be empty if the key is not found. If you're trying to replicate the behavior of isset, you probably want something like if user := r.FormValue("user"); user != "" { ... }

Secondly, you probably want to use PostFormValue (http://godoc.org/net/http#Request.PostFormValue) since in your previous example, you only want to read from POST. Using FormValue is like saying if (isset($_POST["user"]) || isset($_GET["user"])) { ... }.

[amir-taghavi]

thanks my problem solved

func Printuser(w http.ResponseWriter,r *http.Request){

if user:=r.FormValue("user");user!=""{

user = r.FormValue("name")

pass := r.FormValue("pass")

fmt.Fprintf(w,"Hi %s - %s",user,pass)

}

}

and one other question

if i want check 2 parameters example follow

func Printuser(w http.ResponseWriter,r *http.Request){

if user:=r.FormValue("user"),pass:=r.FormValue("pass");user!="" && pass!=""{

user = r.FormValue("name")

pass = r.FormValue("pass")

fmt.Fprintf(w,"Hi %s - %s",user,pass)

}

}

how is it possible ? 

[cm...@golang.org]

You can do multiple assignments in one line with the comma operator e.g. user, pass := r.FormValue("user"), r.FormValue("pass"), but that doesn't seem very idiomatic. Just initialize the variables and then check them:

func PrintUser(w http.ResponseWriter, r *http.Request) {
        user := r.FormValue("user")

        pass := r.FormValue("pass")

        if user == "" || pass == "" {
                fmt.Fprintf(w, "Missing username or password")
                return
        }
        fmt.Fprintf(w, "Hi %s!", user) //I doubt you want to print the password.
}

[amir-taghavi]

very thanks dude

[asadhay...@gmail.com]

It will be a compile time error in go if you use a variable that is not declared ...

[Uzondu Enudeme]

in php we can used isset function to check which variable is set or not set 

<?php

...

if(isset($_POST["name"])){

...

}

...

?>

how is it in golang?

A two-value assignment tests for the existence of a key:

i, ok := m["route"]

In this statement, the first value (i) is assigned the value stored under the key "route". If that key doesn't exist, i is the value type's zero value (0). The second value (ok) is a bool that is trueif the key exists in the map, and false if not.

To test for a key without retrieving the value, use an underscore in place of the first value:

_, ok := m["route"]

I copied the above from here: 

https://blog.golang.org/go-maps-in-action

Do read the full blog article to know more about the go map data type.

Regards,

Uzondu