问题描述
我正在尝试从Firebase实时数据库中获取一些数据。这是我的代码，目的是通过http请求获取数据。我也正在接收数据，并且可以在日志中看到它。
return http.get(placeUrl).then((value) {
var _extractedData = jsonDecode(value.body) as Map<String,dynamic>;
print("Data: $_extractedData");
_extractedData.forEach((_placeName,_details) {
print("Details: $_details");
var _events = _details['events'] as Map<String,dynamic>;
List<EventModel> events = [];
_events != null
? _events.forEach((_event,_eventDetail) {
print("_eventdetail: $_eventDetail");
List<PriceModel> prices = [];
var _price = _eventDetail['price'] as Map<String,dynamic>;
_price != null
? _price.forEach((_type,_typeDetail) {
print("_typeDetail: $_typeDetail");
List<TypeModel> typeModelList = [];
_typeDetail != null
? _typeDetail.forEach((_typeName,_typeSubDetail) {
print("_typeSubDetail: $_typeSubDetail");
var typeModel = TypeModel(
typeName: _typeName.toString(),description:
_typeSubDetail['description'].toString(),price: _typeSubDetail['price'].toString(),);
typeModelList.add(typeModel);
})
: null;
var priceModel = PriceModel(
type: _type,typeData: typeModelList,);
prices.add(priceModel);
})
: null;
var _eventModel = EventModel(
ageLimit: _eventDetail['agelimit'].toString(),date: _eventDetail['date'].toString(),description: _eventDetail['description'].toString(),dressCode: _eventDetail['dresscode'].toString(),eventName: _event,image: _eventDetail['image'].toString(),lineup: _eventDetail['lineup'] as List<dynamic>,prices: prices,stars: double.parse(_eventDetail['stars']),time: _eventDetail['time'].toString(),);
events.add(_eventModel);
})
: null;
var _placeModel = PlaceModel(
description: _details['description'],event: events,images: _details['images'],location: _details['location'],menu: _details['menu'],placeName: _placeName,stars: double.parse("${_details['stars']}"),logo: _details['logo'],);
_places.add(_placeModel);
});
}).then((_) {
print("This is final: ${places[0].images[0]}");
notifyListeners();
}).catchError((e) {
print(e);
});
我得到的日志是：
I/Flutter (25748): Data: {Amethhyyst - Mumbai: {description: In the city that never sleeps,rises a luxury lifestyle lounge built with one sole vision - Live life. One experience at a time!,events: {Saturday club night: {agelimit: 18+,date: Sat 7,Nov 2020,description: It's Club Night and the place will be exploding with amazing music and your tapping on the floor. The party starts at 7 PM,so be there on 07th Nov and rejoice with Dj Manzee @amethhyyst!,dresscode: casuals,image: https://firebasestorage.googleapis.com/v0/b/guestinme-3aafb.appspot.com/o/places%2Famethhyyst%2Fevent%2F07112020_flyer.jpg?alt=media&token=967c8301-7730-40fb-98e4-1dfe07e7e5aa,lineup: [DJ Manzee],price: {crowd: {Couple: {description: 1 male and 1 female only,price: 0},Female: {description: 1 female only,Male Stags: {description: 1 male only,price: 2000}},tables: {Exclusive Table: {description: Exclusive table provided,price: 10000},VIP Table: {decription: VIP table provided,price: 20000}}},time: 19:00 - 01:30}},images: [http
I/Flutter (25748): Details: {description: In the city that never sleeps,images: [https://firebasestorage
I/Flutter (25748): _eventdetail: {agelimit: 18+,description: It's Club Night and the place will be exploding with amazing music
and your tapping on the floor. The party starts at 7 PM,time: 19:00 - 01:30}
I/Flutter (25748): _typeDetail: {Couple: {description: 1 male and 1 female only,Male Stags:
{description: 1 male only,price: 2000}}
I/Flutter (25748): _typeSubDetail: {description: 1 male and 1 female only,price: 0}
I/Flutter (25748): _typeSubDetail: {description: 1 female only,price: 0}
I/Flutter (25748): _typeSubDetail: {description: 1 male only,price: 2000}
I/Flutter (25748): _typeDetail: {Exclusive Table: {description: Exclusive table provided,price: 20000}}
I/Flutter (25748): _typeSubDetail: {description: Exclusive table provided,price: 10000}
I/Flutter (25748): _typeSubDetail: {decription: VIP table provided,price: 20000}
I/Flutter (25748): NoSuchMethodError: The getter 'length' was called on null.
I/Flutter (25748): Receiver: null
I/Flutter (25748): Tried calling: length
我尝试了什么： 我看到了一些与此相关的帖子，并尝试通过初始化列表'[]'来删除null对象上的length方法调用。我还通过if条件检查它们是否确实为null，因此我可以跳过该部分而不运行它（：null;）。
我的Firebase数据：
解决方法
解决了。这是因为我在此处添加了“星星”，而数据库中没有“星星”键。
$headerFooterColor: #4b4276;
$headerFooterHeight: 50px;
$sidebarWidth: 15%;
* {
margin: 0;
padding: 0;
}
html,body {
height: 100%;
text-align: center;
}
#main {
display: flex;
flex-direction: column;
}
#header {
font-size: 1rem;
height: $headerFooterHeight;
background-color: $headerFooterColor;
text-align: center;
color: white;
width: 100%;
left: 0;
position: fixed;
z-index: 1;
top: 0;
height: $headerFooterHeight;
}
.wrapper {
display: flex;
flex: 1 0 0;
margin-top: $headerFooterHeight;
.sidebar {
margin: 0;
padding: 0;
width: $sidebarWidth;
background-color: #b9bcc9;
position: fixed;
height: calc(100% - (2 * #{$headerFooterHeight}));
height: calc(100% - (2 * #{$headerFooterHeight}));
height: calc(100% - (2 * #{$headerFooterHeight}));
margin: 0 auto;
color: white;
}
.sidebar-left {
left: 0;
order: -1;
}
.main {
background-color: rgba(160,194,227,0.5);
text-align: center;
color: white;
width: 70%;
height: calc(100% - (2 * #{$headerFooterHeight}));
overflow: auto;
flex: 1 0 0;
&.fullWidth {
width: 100%;
}
&.leftSidebarEnabled {
margin-left: 15%;
width: 85%;
}
&.rightSidebarEnabled {
margin-right: 15%;
width: 85%;
}
}
.sidebar-right {
right: 0;
order: 1;
}
}
#footer {
font-size: 1rem;
position: fixed;
width: 100%;
bottom: 0;
height: $headerFooterHeight;
left: 0;
background-color: $headerFooterColor;
text-align: center;
color: white;
overflow: auto;
z-index: 1;
}