title: Flutter: Bottom sheet with TextField/TextFormField
body: <p>In part of our application, I would like to have a simple form in <code>BottomSheet</code> like with the below code. unfortunately when i put into that, I get an error</p>
  <blockquote>
  <p>The following assertion was thrown during performLayout(): An
  InputDecorator, which is typically created by a TextField, cannot have
  an unbounded width. This happens when the parent widget does not
  provide a finite width constraint. For example, if the InputDecorator
  is contained by a Row, then its width must be constrained. An Expanded
  widget or a SizedBox can be used to constrain the width of the
  InputDecorator or the TextField that contains it.
  'package:flutter/src/material/input_decorator.dart': Failed assertion:
  line 881 pos 7: 'layoutConstraints.maxWidth &lt; double.infinity'</p>
  </blockquote>
  <p>my implemented code:</p>
  <pre><code>  void _settingModalBottomSheet(context){
      showModalBottomSheet(
          context: context,
          elevation: 8.0,
          builder: (BuildContext bc){
            return Directionality(
              textDirection: TextDirection.rtl,
              child: ConstrainedBox(
                constraints: BoxConstraints(
                  minHeight: 250.0
                ),
                child: Container(
                  padding: EdgeInsets.fromLTRB(0.0,10.0,0.0,10.0),
                  child: new Wrap(
                    children: &lt;Widget&gt;[
                      Padding(
                        padding: const EdgeInsets.all(8.0),
                        child: Center(
                          child: Text(
                            'please fill this form',
                            style: TextStyle(
                              fontSize: 13.0,
                            ),
                          ),
                        ),
                      ),
                      Divider(),
                      Row(
                        mainAxisAlignment: MainAxisAlignment.center,
                        crossAxisAlignment: CrossAxisAlignment.center,
                        children: &lt;Widget&gt;[
                          Column(
                            children: &lt;Widget&gt;[
                              Text('item 1'),
                              Container(
                                child: TextField(),
                              )
                            ],
                          ),
                          Column(
                            children: &lt;Widget&gt;[
                              Text('item 2'),
                              Container(
                                child: TextField(),
                              )
                            ],
                          ),
  
                        ],
                      ),
                    ],
                  ),
                ),
              ),
            );
          }
      );
    }
  </code></pre>