Android data binding attribute not found

Question

I am trying to replicate this answer: Setting attribute of child element of included layout

I have a simple custom_edit_text.xml:

<?xml version="1.0" encoding="utf-8"?>
<layout
    xmlns:android="http://schemas.android.com/apk/res/android">
    <data>
        <variable name="hint123" type="String" />
    </data>
    <android.support.design.widget.TextInputLayout
        android:id="@+id/emailInputLayout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">
        <android.support.v7.widget.AppCompatEditText
            android:id="@+id/emailField"
            android:layout_width="275dp"
            android:layout_height="wrap_content"
            android:paddingBottom="16dp"
            android:paddingTop="14dp"
            android:hint="@{hint123}"
            android:textCursorDrawable="@null"
            android:background="@drawable/edit_text_background"
            android:fontFamily="@font/eina_regular"
            android:textColor="@color/edit_text_color"
            android:textColorHint="@color/edit_text_color"
            android:textSize="15sp"
            />
    </android.support.design.widget.TextInputLayout>
</layout>

And I include it in another file:

<?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">
    <include
            layout="@layout/custom_edit_text"
            app:hint123="Email"/>
</layout>

However the project refuses to compile after a clean & rebuild with the error:

AAPT: error: attribute hint123 (aka inc.company.appname:hint123) not found.

Any ideas?

I also have

dataBinding {
    enabled = true
}

enabled in the app level build.gradle

At a 10 second glance I would say you Android Studio/Operating System is old, would I be right ? — Jon Goodwin
– Jon Goodwin, Commented Mar 12, 2019 at 3:57
Rather than app:hint123="Email", pass like this app:hint123="@{Email}" in include layout. — Jeel Vankhede
– Jeel Vankhede, Commented Mar 12, 2019 at 4:57
@JeelVankhede that did it, it compiles! However, now when I pass a raw string value, it does not populate in the included view. — Josh
– Josh, Commented Mar 12, 2019 at 5:11

big_m · Accepted Answer · 2019-09-30 23:55:31Z

57

I think I've hit upon the solution. To activate data binding, you need to use a @{} expression, and what's in the braces must be valid Java code. So a literal string must be enclosed in quotes... which must be encoded as " inside an XML attribute value. Put it all together and you get:

<include
    layout="@layout/custom_edit_text"
    app:hint123="@{&quot;Email&quot;}"/>

Data binding does work for include files, it's just that the syntax for a literal is a bit convoluted. I had the same issue and this form is working in my project.

answered Sep 30, 2019 at 23:55

big_m

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4 Comments

alexanderktx Over a year ago

Thanks a lot. This is a very strange behavior. I hope it will be fixed soon.

Daniel Wilson Over a year ago

...or at least a descriptive error message that explains this simple issue

Christopher Pickslay Over a year ago

Excellent explanation of what's going on here. Not sure I would have ever come up with this solution. It's unfortunate that there are no examples of this usage in the layout and bindings expressions docs: developer.android.com/topic/libraries/data-binding/expressions.

rminaj Over a year ago

I regret to inform everyone that this issue still persist. But it seems that you can do something like app:hint123='@{"Email"}' instead if you don't want/need to use "

Braian Coronel · Accepted Answer · 2020-07-22 21:50:13Z

8

Bind the variables using @{ }

activity_main.xml

</layout>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".simple.MainActivity">

        <include layout="@layout/content_main_data_binding"
            bind:name="@{ "Hello World" }" />
    
    </androidx.constraintlayout.widget.ConstraintLayout>

</layout>

content_view.xml

</layout>

    <data>
    <variable
        name="name"
        type="String" />
    </data>

    <TextView
            android:id="@+id/text"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{ name }"/>

 </layout>

GL

edited Jul 22, 2020 at 21:50

answered Apr 6, 2020 at 2:23

Braian Coronel

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3 Comments

mosh.jinton Over a year ago

bind:name isn't working for me, 'Namespace: 'bind' is not bound'

Braian Coronel Over a year ago

Add xmlns:bind="http://schemas.android.com/tools" in your parent layout

Christopher Pickslay Over a year ago

Your binding expression is not valid xml

Christopher Pickslay · Accepted Answer · 2023-02-01 02:48:12Z

3

There are 2 alternatives to the quote-escaping solution @big_m provides.

You can single-quote the entire expression and use double-quotes around the string:

<include
    layout="@layout/custom_edit_text"
    app:hint123='@{"Email"}'/>

Or you can use backticks around the string:

<include
    layout="@layout/custom_edit_text"
    app:hint123="@{`Email`}"/>

answered Feb 1, 2023 at 2:48

Christopher Pickslay

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1 Comment

big_m Over a year ago

Much easier on the eyes, @Christopher! I can't believe I didn't think of using the single quotes, but thanks for that! Is there a minimum version of the tools or Java where the backticks work? I looked for information on that format, as I hadn't seen it before, and everything I found said that Java ended up not adopting the backticks, but it does seem to work with the Android SDK 34 toolset.

novice_2 · Accepted Answer · 2019-03-18 07:22:05Z

I am using Android 3.1.1. And the following code is working for me, and if you can use it you will be able to reuse "hint" as you desired. I have a slightly altered layout file (custom_edit_text.xml) as follows.

<?xml version="1.0" encoding="utf-8"?>

<data>
    <variable name="cName" type="String" />
    <variable name="user" type="your.package.name.User" />
</data>

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

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@{user.email}" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@{user.mobile}" />

    <android.support.design.widget.TextInputLayout
        android:id="@+id/emailInputLayout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">

        <android.support.v7.widget.AppCompatEditText
            android:layout_width="match_parent"
            android:layout_height="50dp"
            android:hint="@{cName.toString()}"
            android:paddingBottom="16dp"
            android:paddingTop="14dp"
            android:textSize="15sp" />

    </android.support.design.widget.TextInputLayout>
</LinearLayout>

Above the second "type" is package name + User class name.

I create the "User" class in a separate file as follows.

public class User {
String email;
String mobile;

User(String email, String mobile) {
    this.email = email;
    this.mobile = mobile;
}


public String getEmail() {
    return email;
}

public String getMobile() {
    return mobile;
}
}

Inside MainActivity inside onCreate() I create the user object create the string and bind them.

String email = "xyz@yahoo";
    String mobile = "9999";
    User user = new User(email,mobile);
    CustomEditTextBinding binding = DataBindingUtil.setContentView(this,R.layout.custom_edit_text) ;
    binding.setCName("Yam May");
    binding.setUser(user);

And I enabled binding in the app level build.gradle as you did.

A very detailed description about data binding can be found in https://www.vogella.com/tutorials/AndroidDatabinding/article.html

don't forget to add the dataBinding element to your build.gradle file in the app module android { ... dataBinding { enabled = true } }

nayakasu · Accepted Answer · 2023-01-03 08:58:08Z

0

Just in case anyone misses one detail like me: you must enclose your parent layout content and the included layout content within "" and "". Without that binding is not used in a layout. I had the same issue when I had not enclosed my parent layout with these tags.

answered Jan 3, 2023 at 8:58

nayakasu

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Comments

Himanshu Likhyani · Accepted Answer · 2024-05-25 14:32:20Z

0

This error can also occur when <layout> tag is not placed upon the calling layout.
(the xml within which we're using the <include> tag and setting a binding attribute value as bind:myvariable or app:myvariable)

PS: Not the case presented in this issue, but just something to be wary of.

edited May 25, 2024 at 14:32

answered May 10, 2024 at 11:00

Himanshu Likhyani

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