Android Data Binding: how to pass variable to include layout

Question

Google documentation says that variables may be passed into an included layout's binding from the containing layout but I can't make it work but get data binding error ****msg:Identifiers must have user defined types from the XML file. handler is missing it. The including XML looks like this:

<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:bind="http://schemas.android.com/apk/res-auto">

<data>
    <import type="com.example.FocusChangeHandler"/>

    <variable
        name="handler"
        type="FocusChangeHandler"/>
</data>

<!-- Some other views  --->

   <include
            android:id="@+id/inputs"
            layout="@layout/input_fields"
            bind:handler="@{handler}"/>        
</layout>

And the included XML like this:

<layout xmlns:android="http://schemas.android.com/apk/res/android">
<EditText
   android:id="@+id/nameEdit"       
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"       
   android:onFocusChange="@{handler.onFocusChange}"/>
</layout>

I'm able to refer the Views from included layout through generated binding class but passing a variable just doesn't work.

score 25 · Answer 1 · edited Jun 20 '20 at 09:12

25

Just create <variable for passing values to included layouts.

Like app:passedText="@{@string/app_name}"

Example

Like I want to pass String to included layout. I will create a variable of type String. Refer that String to your TextView. I created passedText for example.

<?xml version="1.0" encoding="utf-8"?>
<layout
    xmlns:android="http://schemas.android.com/apk/res/android"
    >

    <data>
        // declare fields
        <variable
            name="passedText"
            type="String"/>
    </data>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@{passedText}"/> //set field to your view.

</layout>

Now add passedText field to your <include tag.

<?xml version="1.0" encoding="utf-8"?>
<layout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        >

        <include
            layout="@layout/layout_common"
            app:passedText="@{@string/app_name}" // here we pass any String 
            />

    </LinearLayout>
</layout>

Note that both layouts (parent & included) should be binding layout, wrapped with <layout

edited Jun 20 '20 at 09:12

Community

1
1

answered Aug 01 '18 at 12:32

Khemraj Sharma

57,232
27
203
212

1

Remember to call `DataBindingUtil.setContentView(this, R.layout.fragment_offer_detail)`, EVEN if you're not using any of its elements. – Morgan Koh Aug 14 '18 at 09:32
2

@DelacrixMorgan See https://stackoverflow.com/a/51633632/6891563, please don't use `DataBindingUtil` for Fragments & Dialogs. – Khemraj Sharma Aug 14 '18 at 09:34
Simple and crisp! – User3 Nov 01 '19 at 04:39
1

@CosmicDev yes you can take multiple strings variables, there is no limit. – Khemraj Sharma May 28 '20 at 09:29
This doesn't work for me. Is there anything else im missing except for these 2 code snippets? Do fragments (kotlin) files need something extra? – obey Sep 01 '21 at 08:12
@Patrick please read full answer, it will work. It is working solution. – Khemraj Sharma Oct 04 '21 at 17:25

score 14 · Accepted Answer · answered Feb 18 '16 at 21:38

14

The documentation specifies

Here, there must be a user variable in both the name.xml and contact.xml layout files

I assume you should have this in your included layout:

    <data>
           <variable name="handler"
                     type="FocusChangeHandler"/>
    </data>

answered Feb 18 '16 at 21:38

Batgard

156
1
4

Funny but I already tried this when I was playing with it and got an error about variable being defined multiple times. Something must have been changed between Android Studio 2.0 Beta 3 and Beta 5 as it seems to work now. – pmellaaho Feb 22 '16 at 07:11
1

Is it possible to pass multiple variables? I've tried: ` ` but that doesn't seem to work. – b.lyte Sep 25 '16 at 15:37

score 9 · Answer 3 · answered Jan 30 '19 at 21:49

9

For hardcoded string:

 android:label="@{`Test 123`}"

answered Jan 30 '19 at 21:49

Gene Bo

11,284
8
90
137

1

Not working for me. attribute not found – Patrick Sep 22 '21 at 08:08

Android Data Binding: how to pass variable to include layout

3 Answers3

Example