Alert box with multi select chip in flutter

In AlertDialog's content use Container and constraints, and in Container's child wrap SingleChildScrollView then wrap MultiSelectChip

code snippet

return AlertDialog(
            title: Text("Report Video"),
            content: Container(
              constraints: BoxConstraints(
                  maxHeight: 100.0,
              ),
              child: SingleChildScrollView(
                child: MultiSelectChip(
                  reportList,
                  onSelectionChanged: (selectedList) {
                    setState(() {
                      selectedReportList = selectedList;
                    });
                  },
                ),
              ),
            ),
            actions: <Widget>[
              FlatButton(
                child: Text("Report"),
                onPressed: () => Navigator.of(context).pop(),
              )
            ],
          );
        })

full code

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  List<String> reportList = [
    "Not relevant",
    "Illegal",
    "Spam",
    "Offensive",
    "Uncivil",
    "a123",
    "b234",
    "c2314",
    "aaaa",
    "a",
    "1Not relevant",
    "2Illegal",
    "3Spam",
    "4Offensive",
    "5Uncivil",
    "6a123",
    "7b234",
    "8c2314",
    "9aaaa",
    "0a",
    "Not relevant",
    "Illegal",
    "Spam",
    "Offensive",
    "Uncivil",
    "a123",
    "b234",
    "c2314",
    "aaaa",
    "a",
    "1Not relevant",
    "2Illegal",
    "3Spam",
    "4Offensive",
    "5Uncivil",
    "6a123",
    "7b234",
    "8c2314",
    "9aaaa",
    "0a",
  ];

  List<String> selectedReportList = List();

  _showReportDialog() {
    showDialog(
        context: context,
        builder: (BuildContext context) {
          //Here we will build the content of the dialog
          return AlertDialog(
            title: Text("Report Video"),
            content: Container(
              constraints: BoxConstraints(
                  maxHeight: 100.0,
              ),
              child: SingleChildScrollView(
                child: MultiSelectChip(
                  reportList,
                  onSelectionChanged: (selectedList) {
                    setState(() {
                      selectedReportList = selectedList;
                    });
                  },
                ),
              ),
            ),
            actions: <Widget>[
              FlatButton(
                child: Text("Report"),
                onPressed: () => Navigator.of(context).pop(),
              )
            ],
          );
        });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          crossAxisAlignment: CrossAxisAlignment.center,
          children: <Widget>[
            RaisedButton(
              child: Text("Report"),
              onPressed: () => _showReportDialog(),
            ),
            Text(selectedReportList.join(" , ")),
          ],
        ),
      ),
    );
  }
}

class MultiSelectChip extends StatefulWidget {
  final List<String> reportList;
  final Function(List<String>) onSelectionChanged;

  MultiSelectChip(this.reportList, {this.onSelectionChanged});

  @override
  _MultiSelectChipState createState() => _MultiSelectChipState();
}

class _MultiSelectChipState extends State<MultiSelectChip> {
  // String selectedChoice = "";
  List<String> selectedChoices = List();

  _buildChoiceList() {
    List<Widget> choices = List();

    widget.reportList.forEach((item) {
      choices.add(Container(
        padding: const EdgeInsets.all(2.0),
        child: ChoiceChip(
          label: Text(item),
          selected: selectedChoices.contains(item),
          onSelected: (selected) {
            setState(() {
              selectedChoices.contains(item)
                  ? selectedChoices.remove(item)
                  : selectedChoices.add(item);
              widget.onSelectionChanged(selectedChoices);
            });
          },
        ),
      ));
    });

    return choices;
  }

  @override
  Widget build(BuildContext context) {
    return Wrap(
      children: _buildChoiceList(),
    );
  }
}