import 'package:flutter/material.dart';
import 'package:flutter_myapp/AllWidgets/Divider.dart';
import 'package:flutter_myapp/AllWidgets/progressDialog.dart';
import 'package:flutter_myapp/Assistants/requestAssistant.dart';
import 'package:flutter_myapp/DataHandler/appData.dart';
import 'package:flutter_myapp/Models/address.dart';
import 'package:flutter_myapp/Models/placePredictions.dart';
import 'package:flutter_myapp/configMaps.dart';
import 'package:provider/provider.dart';
class SearchScreen extends StatefulWidget {
@override
_SearchScreenState createState() => _SearchScreenState();
}
class _SearchScreenState extends State<SearchScreen>
{
TextEditingController pickUpTextEditingController = TextEditingController();
TextEditingController dropOffTextEditingController = TextEditingController();
List<PlacePredictions> placePredictionList = [];
@override
Widget build(BuildContext context)
{
String placeAddress = Provider.of<AppData>(context).pickUpLocation.placeName ?? "";
pickUpTextEditingController.text = placeAddress;
return Scaffold(
body: Column(
children: [
Container(
height: 215.0,
decoration: BoxDecoration(
color: Colors.white,
boxShadow: [
BoxShadow(
color: Colors.black,
blurRadius: 6.0,
spreadRadius: 0.5,
offset: Offset(0.7, 0.7),
),
],
),
child: Padding(
padding: EdgeInsets.only(left: 25.0, top: 25.0, bottom: 20.0),
child: Column(
children: [
SizedBox(height: 5.0),
Stack(
children: [
GestureDetector(
onTap:()
{
Navigator.pop(context);
},
child: Icon(
Icons.arrow_back
),
),
Center(
child: Text("Set Drop Off", style: TextStyle(fontSize: 18.0, fontFamily: "Brand Bold"),),
)
],
),
SizedBox(height: 16.0),
Row(
children: [
Image.asset("images/pickicon.png", height: 16.0, width: 16.0,),
SizedBox(width: 18.0,),
Expanded(
child: Container(
decoration: BoxDecoration(
color: Colors.grey[400],
borderRadius: BorderRadius.circular(5.0),
),
child: Padding(
padding: EdgeInsets.all(3.0),
child: TextField(
controller: pickUpTextEditingController,
decoration: InputDecoration(
hintText: "PickUp Location",
fillColor: Colors.grey[400],
filled: true,
border: InputBorder.none,
isDense: true,
contentPadding: EdgeInsets.only(left: 11.0, top: 8.0, bottom: 8.0),
),
),
),
),
),
],
),
SizedBox(height: 10.0),
Row(
children: [
Image.asset("images/desticon.png", height: 16.0, width: 16.0,),
SizedBox(width: 18.0,),
Expanded(
child: Container(
decoration: BoxDecoration(
color: Colors.grey[400],
borderRadius: BorderRadius.circular(5.0),
),
child: Padding(
padding: EdgeInsets.all(3.0),
child: TextField(
onChanged: (val)
{
findPlace(val);
},
controller: dropOffTextEditingController,
decoration: InputDecoration(
hintText: "Where to? ",
fillColor: Colors.grey[400],
filled: true,
border: InputBorder.none,
isDense: true,
contentPadding: EdgeInsets.only(left: 11.0, top: 8.0, bottom: 8.0),
),
),
),
),
),
],
),
],
),
),
),
//tile for predictions
SizedBox(height: 10.0,),
(placePredictionList.length > 0)
?Padding(
padding: EdgeInsets.symmetric(vertical: 8.0, horizontal: 16.0),
child: ListView.separated(
padding: EdgeInsets.all(0.0),
itemBuilder: (context, index)
{
return PredictionTile(placePredictions: placePredictionList[index],);
},
separatorBuilder: (BuildContext context, int index) => DividerWidget(),
itemCount: placePredictionList.length,
shrinkWrap: true,
physics: ClampingScrollPhysics(),
),
)
:Container(),
],
),
);
}
void findPlace(String placeName) async
{
if(placeName.length > 1)
{
String autoCompleteUrl = "https://maps.googleapis.com/maps/api/place/autocomplete/json?input=$placeName&key=$mapKey&sessiontoken=1234567890&components=country:us";
var res = await RequestAssistant.getRequest(autoCompleteUrl);
if(res == "failed")
{
return;
}
//print("Places Predictions Response :: ");
//print(res);
if(res["status"] == "OK")
{
var predictions = res["predictions"];
var placeList = (predictions as List).map((e) => PlacePredictions.fromJson(e)).toList();
setState(() {
placePredictionList = placeList;
});
}
}
}
}
class PredictionTile extends StatelessWidget
{
final PlacePredictions placePredictions;
PredictionTile({Key key,this.placePredictions}) : super(key: key);
@override
Widget build(BuildContext context)
{
return FlatButton(
padding: EdgeInsets.all(0.0),
onPressed: ()
{
getPlaceAddressDetails(placePredictions.place_id, context);
},
child: Container(
child: Column(
children: [
SizedBox(width: 10.0,),
Row(
children: [
Icon(Icons.add_location),
SizedBox(width: 14.0,),
Expanded(
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
SizedBox(height: 8.0,),
Text(placePredictions.main_text, overflow: TextOverflow.ellipsis, style: TextStyle(fontSize: 16.0),),
SizedBox(height: 2.0,),
Text(placePredictions.secondary_text, overflow: TextOverflow.ellipsis, style: TextStyle(fontSize: 12.0, color: Colors.grey),),
SizedBox(height: 8.0,),
],
),
),
],
),
SizedBox(width: 10.0,),
],
),
),
);
}
void getPlaceAddressDetails(String placeId, context) async
{
showDialog(
context: context,
builder: (BuildContext context) => ProgressDialog(message: "Setting Drop off, Please wait....",),
);
String placeDetailsUrl = "https://maps.googleapis.com/maps/api/place/details/json?place_id=$placeId&key=$mapKey";
var res = await RequestAssistant.getRequest(placeDetailsUrl);
Navigator.pop(context);
if(res == "failed")
{
return;
}
if(res["status"] == "OK")
{
Address address = Address();
address.placeName = res["result"]["name"];
address.placeId = placeId;
address.latitude = res["result"]["geometry"]["location"]["lat"];
address.longitude = res["result"]["geometry"]["location"]["lng"];
Provider.of<AppData>(context, listen: false).updateDropOffLocationAddress(address);
print("This is Drop Off Location :: ");
print(address.placeName);
Navigator.pop(context, "obtainDirection");
}
}
}
请帮帮我，我不明白出了什么问题。
我不断收到此错误。
小部件库捕获的异常：
<块引用>构建 PredictionTile(dirty) 时抛出以下断言：A 必须向文本小部件提供非空字符串。 'package:flutter/src/widgets/text.dart'：断言失败：第 380 行 位置 10: '数据 != null'
答案 0 :(得分：2)
Text Widget 不能包含 null 数据，错误依赖于以下几行：
Text(placePredictions.main_text, overflow: TextOverflow.ellipsis, style: TextStyle(fontSize: 16.0),),
Text(placePredictions.secondary_text, overflow: TextOverflow.ellipsis, style: TextStyle(fontSize: 12.0, color: Colors.grey),),
要修复它，我们可以将它们更改为：
Text(placePredictions.main_text ?? 'n/a', overflow: TextOverflow.ellipsis, style: TextStyle(fontSize: 16.0),),
Text(placePredictions.secondary_text ?? 'n/a', overflow: TextOverflow.ellipsis, style: TextStyle(fontSize: 12.0, color: Colors.grey),),
用“n/a”替换 null 数据。