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.

Community · Accepted Answer · 2020-06-20 09:12:55Z

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, 2020 at 9:12

CommunityBot

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answered Aug 1, 2018 at 12:32

Khemraj Sharma

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6 Comments

Morgan Koh Over a year ago

Remember to call DataBindingUtil.setContentView<FragmentOfferDetailBinding>(this, R.layout.fragment_offer_detail), EVEN if you're not using any of its elements.

Khemraj Sharma Over a year ago

@DelacrixMorgan See stackoverflow.com/a/51633632/6891563, please don't use DataBindingUtil for Fragments & Dialogs.

User3 Over a year ago

Simple and crisp!

Khemraj Sharma Over a year ago

@CosmicDev yes you can take multiple strings variables, there is no limit.

obey Over a year ago

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?

|

Batgard · Accepted Answer · 2016-02-18 21:38:13Z

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, 2016 at 21:38

Batgard

1561 silver badge4 bronze badges

2 Comments

pmellaaho Over a year ago

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.

b.lyte Over a year ago

Is it possible to pass multiple variables? I've tried: <variable name="onClick" type="android.view.View.OnClickListener"/> <variable name="buttonText" type="String"/> but that doesn't seem to work.

Gene Bo · Accepted Answer · 2019-01-30 21:49:03Z

9

For hardcoded string:

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

answered Jan 30, 2019 at 21:49

Gene Bo

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1 Comment

Patrick Over a year ago

Not working for me. attribute not found

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