Navigation component: parcelable argument but get error Type mismatch: inferred type is Student but String was expected

Question

In my root build.gradle I have navigation-safe-args-gradle-plugin version 2.2.0-rc03:

script{
   dependencies {
        classpath 'com.android.tools.build:gradle:3.5.3'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath 'androidx.navigation:navigation-safe-args-gradle-plugin:2.2.0-rc03'
    }
}

In my navigation graph xml:

<fragment
        android:id="@+id/MyListFragment"
        android:name="com.foo.bar.ui.mylist.MyListFragment"
        android:label="My List">

        <action
            android:id="@+id/action_myListFragment_to_myDetailFragment"
            app:destination="@id/myDetailFragment" />

        <!--Here I pass parcelable type as argument-->
        <argument
            android:name="Student"
            app:argType="com.foo.core.model.Student"/>

    </fragment>

Student is a normal class.

package com.foo.core.model

@Parcelize
data class Student(val studentNumber: Int): Parcelable

In my fragment I do:

val student:Student=Student(123)
findNavController().navigate(actionMyListFragmentToMyDetailFragment(student))

When I build my project, I get compiler error:

Type mismatch: inferred type is Student but String was expected

Why is that?

Answer 1

put your argument in MyDetailsFragment not MyListFragment so

MyListFragment

<fragment
    android:id="@+id/MyListFragment"
    android:name="com.foo.bar.ui.mylist.MyListFragment"
    android:label="My List">

    <action
        android:id="@+id/action_myListFragment_to_myDetailFragment"
        app:destination="@id/MyDetailsFragment" />

</fragment>

MyDetailsFragment

<fragment
    android:id="@+id/MyDetailsFragment"
    android:name="com.foo.bar.ui.mylist.MyDetailsFragment"
    android:label="My Details">

    <argument
        android:name="Student"
        app:argType="com.foo.core.model.Student"/>

</fragment>