:compass: Navigation: when calling `arguments?.getString` ,which `userId` should be used? red or yel...

# compose

[theapache64]

🧭 Navigation: when calling arguments?.getString ,which userId should be used? red or yellow? and what abt navArgument? 🤔

[Filip Wiesner]

I would assume yellow because that's the parameter name 😄

[Filip Wiesner]

And the red is for navArgument() I guess

[theapache64]

Oookay 😄 I’ll try that

[Filip Wiesner]

Let me know when you find out 😅

[theapache64]

@Ian Lake I think it’d be great if you guys can use different names here. Its little confusing

[theapache64]

@Filip Wiesner sure

[JulianK]

I'm using path arguments like this:

route = "profile/{userId}"
navArgument("userId")
params.backStackEntry.arguments?.getLong("userId")

So in your case... red is the the thing to query for, i guess?

[JulianK]

It's also in the docs: https://developer.android.com/jetpack/compose/navigation#nav-with-args

[theapache64]

@JulianK yeah pathArgs doesn’t make any confusion. but optional arg example kinda confusing. didn’t try it though.

[Filip Wiesner]

Did you test the yellow/red parameters @theapache64? I am kinda curious how it actually is 😄

[theapache64]

@Filip Wiesner

Code

composable("A"){
    Button(onClick = {
        mainNavController.navigate("B?theKey=myValue")
    }) {
        Text(text = "GO TO B")
    }
}
composable("B?theKey={theValue}"){
    println("via theKey : ${it.arguments?.getString("theKey")}")
    println("via theValue : ${it.arguments?.getString("theValue")}")
}

Output

via theKey : null
via theValue : myValue

😄

[Filip Wiesner]

😞 So it was the red arrow. It's weird that when getting an argument from url it does not use the parameter name. But I think it kinda makes sense because it takes the whole url as path and extracts only the specified "arguments" in curly braces.
So it does not and does make sense at the same time 🙃

[theapache64]

Another interesting output with the same navigate call as above

Code

composable("B?theKey={theValue}", arguments = listOf(
    navArgument("theKey") { defaultValue = "theDefaultValue" }
)) {
    println("via theKey : ${it.arguments?.getString("theKey")}")
    println("via theValue : ${it.arguments?.getString("theValue")}")
}

Output

via theKey : theDefaultValue
via theValue : myValue

[theapache64]

It makes sense when we look closely at the code 😄 We asked nav to return theDefaultValue when theKey is null. Since the argument.getString looks for the “placeholder value”, theyKey is null and returned its default value ie theDefaultValue

[Filip Wiesner]

Yeah, that makes sense. But I think the argument just shouldn't have name at all and it should be like this: B?theKey={}. It would be less confusing

[theapache64]

Yeah. I agree.