Flutter List Picker

CommodityPicker.dart

import 'package:flutter/material.dart';
import 'package:test_app/models/commodities_model.dart';

class CommodityPicker extends StatelessWidget {

  CommodityPicker(this.commodityMap, this.selected);
  final Map<String, Commodity> commodityMap; // VM
  final String selected; // VM
  @override
  Widget build(BuildContext context) {
    final _names = commodityMap.values.map((c) => c.name).toList(); // VM
    final _symbols = commodityMap.values.map((c) => c.symbol).toList(); // VM
    return Scaffold(
        backgroundColor: Colors.white,
        appBar: AppBar(title: Text("Commodity")), // VM
        body: Column(children: <Widget>[
          SizedBox(height: 20),
          Expanded(
            child: ListView.separated(
                itemCount: _names.length, // VM
                itemBuilder: (BuildContext ctxt, int index) {
                  final commodity = _names[index]; // VM
                  final isSelected = _symbols[index] == selected; // VM
                  return FlatButton(
                      child: SafeArea(
                          child: Row(
                            children: <Widget>[Expanded(child: Text(commodity)), Text(isSelected ? "√" : "")],
                          )),
                      padding: EdgeInsets.symmetric(vertical: 0, horizontal: 20.0),
                      materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
                      onPressed: () => Navigator.pop(ctxt, _symbols[index]), // COORDINATOR
                    );
                },
                separatorBuilder: (BuildContext ctxt, int index) {
                  return Divider();
                }
            )
          ),
        ]));
  }

}