How to use Expanded in SingleChildScrollView?

How to Use Expanded in SingleChildScrollView? 📏🔄😮

Are you struggling to use the Expanded widget inside a SingleChildScrollView in your Flutter app? Don't worry, you're not alone! Many developers face this issue and find it tricky to wrap the column with SingleChildScrollView without encountering errors. In this guide, we will walk you through the steps to solve this problem and ensure smooth scrolling even when the keyboard is open. Let's get started! 💪

The Problem 🤔

Let's take a look at the context of the problem. You have a screen that includes an image, a list view, and a row containing a text form field and an icon button. You wrapped the list view with Expanded, but now you want to wrap the entire column with a SingleChildScrollView so that you can scroll the screen when the keyboard is open.

The Error Message 🚫🚧

Unfortunately, when you wrap the column with SingleChildScrollView, you encounter the following error:

RenderFlex children have non-zero flex but incoming height constraints are unbounded.

The Solution 🙌

To solve this issue, follow these simple steps:

1. Remove the Expanded widget that wraps the ListView.builder.

2. Set the shrinkWrap property of the ListView.builder to true.

3. Wrap the Column with a SingleChildScrollView.

Your modified code should look like this:

SingleChildScrollView(
  child: Column(
    children: <Widget>[
      Container(
        child: GestureDetector(
          child: Image.network(
            postOne.imageUrl,
            fit: BoxFit.fitWidth,
            height: MediaQuery.of(context).size.width,
            width: MediaQuery.of(context).size.width,
          ),
          onLongPress: () {},
          onDoubleTap: () {},
        ),
      ),
      ListView.builder(
        shrinkWrap: true, // Add this line
        itemCount: commentList.length,
        itemBuilder: (context, position) {
          return GestureDetector(
              onLongPress: () {},
              child: Card(
                child: Padding(
                  padding: EdgeInsets.all(5.0),
                  child: CheckboxListTile(
                    title: Text(
                      commentList.elementAt(position).coment,
                      style: TextStyle(fontSize: 18.0),
                    ),
                    value: values[commentList.elementAt(position).coment],
                    onChanged: (bool value) {},
                  ),
                ),
              ));
        },
      ),
      Container(
        child: Row(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Flexible(
              child: Theme(
                data: ThemeData(
                    brightness: Brightness.light,
                    primarySwatch: Colors.grey,
                    inputDecorationTheme: InputDecorationTheme(
                      labelStyle: TextStyle(
                        color: Colors.black45,
                        fontSize: 18.0,
                      ),
                    )),
                child: Form(
                  key: _formKey,
                  child: TextFormField(
                    validator: (value) {
                      if (value.isEmpty) {
                        return 'Please enter the comment';
                      }
                    },
                    controller: commentController,
                    decoration: InputDecoration(
                      labelText: "Add comment",
                      //hintText: 'Add comment'
                    ),
                    keyboardType: TextInputType.text,
                  ),
                ),
              ),
            ),
            Container(
              margin: EdgeInsets.only(left: 10.0, top: 12.0),
              child: IconButton(
                icon: Icon(Icons.send, color: Colors.black,),
                onPressed: () {},
              ),
            ),
          ],
        ),
      ),
    ],
  ),
),

Explanation 📝

The error occurred because the Expanded widget inside the SingleChildScrollView caused a conflict between the children's flexible sizes and the unbounded height of the parent. To resolve this conflict and allow scrolling, we removed the Expanded widget from the ListView.builder and set the shrinkWrap property to true. This allows the list view to size itself based on its children. Finally, we wrapped the entire column with SingleChildScrollView.

Conclusion and Next Steps 👏

By following these steps, you should now be able to use the Expanded widget inside a SingleChildScrollView without encountering any errors. Try implementing this solution in your code and see if it solves your problem. If you have any further questions or encounter any issues, feel free to leave a comment below, and we'll be happy to help! Happy coding! 😄👩‍💻👨‍💻