Safeargs library doesnt generate direction class

Question

I use navigation library and safeargs for passing data. I define argument to fragment like that.

Answer 1

I forgot to apply plugin in app.gradle file, just add this line

apply plugin: "androidx.navigation.safeargs.kotlin"

or this line if you are using java

apply plugin: "androidx.navigation.safeargs"

Answer 2

Took a bit to figure out but you need both action and arguments in your nav xml file to generate both.

<fragment
    android:id="@+id/nav_someId"
    android:name=".CategoriesFragment"
    android:label="@string/someName"
    tools:layout="@layout/fragment_categories">
    <argument
        android:name="@string/category"
        android:defaultValue="0"
        app:argType="string" />
    <action
        android:id="@+id/startCategoriesFragment"
        app:destination="@+id/categoriesFragment">
        <argument
            android:name="@string/category"
            android:defaultValue="0"
            app:argType="string" />
    </action>
</fragment>

Answer 3

Following two steps works for me:

1. Clean project.
2. Rebuild project

Android studio 4.0 Kotlin 1.3.72

Answer 4

Also make sure to use an up to date version. Had the problem, that I had an 1.X version.

// Navigation
implementation "androidx.navigation:navigation-fragment-ktx:2.2.1"
implementation "androidx.navigation:navigation-ui-ktx:2.2.1"

And the args correctely in the nav.xml:

<fragment
    android:id="@+id/categoryFragment"
    android:name="com...CategoryFragment"
    android:label="CategoryFragment"
    tools:layout="@layout/fragment_category">
    <action
        android:id="@+id/action_categoryFragment_to_ProductFragment" // /!\
        app:destination="@id/productFragment"
        <argument
            android:name="products"
            android:defaultValue=""
            app:argType="string" />
    </action>
</fragment>

Code:

override fun onItemClicked(category: Category) {
     val action = CategoryFragmentDirections.actionCategoryToProductFragment(products = "myString") // /!\
     view?.findNavController()?.navigate(action)
}

Answer 5

the problem may be with your apply plugin thing please check if you are using java then add:

apply plugin: "androidx.navigation.safeargs"

and for kotlin use this:

apply plugin: "androidx.navigation.safeargs.kotlin"

Answer 6

I faced a similar issue working with android studio 4.2 preview.

The issue was that the IDE somehow was not picking the source folders where the generated direction classes where being placed by the plugin. So adding the following to my app build.gradle file resolved the issue for me.

sourceSets {
    main {
        java {
            srcDirs += 'build/generated/source/navigation-args'
        }
    }
}

Hope this helps!