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Firebase 错误：flatter/lib/ui/ui#u dart_state.cc（177）未处理的异常：NoSuchMethodError:The method'；插入'；被调用为空

firebase flutter dart google-cloud-firestore

Firebase 错误：flatter/lib/ui/ui#u dart_state.cc（177）未处理的异常：NoSuchMethodError:The method'；插入'；被调用为空,firebase,flutter,dart,google-cloud-firestore,flutter-dependencies,Firebase,Flutter,Dart,Google Cloud Firestore,Flutter Dependencies,你好，我是一个入门的flutter开发人员，我想用我的CloudFireStore数据库中的数据做一个列表。我不知道该怎么做。如果您对我的代码有任何帮助或建议，我们将不胜感激 import 'package:cloud_firestore/cloud_firestore.dart'; import 'package:dinghy1/components/default_button.dart'; import 'package:dinghy1/services/reservations.dart

你好，我是一个入门的flutter开发人员，我想用我的CloudFireStore数据库中的数据做一个列表。我不知道该怎么做。如果您对我的代码有任何帮助或建议，我们将不胜感激

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:dinghy1/components/default_button.dart';
import 'package:dinghy1/services/reservations.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import 'package:flutter_svg/flutter_svg.dart';

import '../../../constants.dart';
import '../../../size_config.dart';

class Body extends StatefulWidget {
  @override
  _BodyState createState() => _BodyState();
}

class _BodyState extends State<Body> {
  static List<Map<String, dynamic>> reservations;
  static Map<String, dynamic> documents;
  static List<QueryDocumentSnapshot> documents2;
  static int index;
  bool visibility = false;
  String rental = ReservationService.rental;
  @override
  Widget build(BuildContext context) {
    return SingleChildScrollView(
      child: SafeArea(
        child: Column(
          children: [
            SizedBox(
              height: getPropotionateScreenWidth(20),
            ),
            Padding(
              padding: EdgeInsets.symmetric(
                  horizontal: getPropotionateScreenWidth(20)),
              child: Container(
                decoration: BoxDecoration(
                    color: kPrimaryColor.withOpacity(0.4),
                    borderRadius: BorderRadius.circular(30)),
                height: getPropotionateScreenHeight(75),
                width: double.infinity,
                child: Center(
                  child: Text(
                    "Sprawdź rezerwacje",
                    style: TextStyle(
                        fontSize: getPropotionateScreenWidth(20),
                        fontWeight: FontWeight.bold),
                    textAlign: TextAlign.center,
                  ),
                ),
              ),
            ),
            SizedBox(
              height: getPropotionateScreenWidth(20),
            ),
            DatePicker(),
            SizedBox(
              height: getPropotionateScreenWidth(20),
            ),
            Padding(
              padding: EdgeInsets.symmetric(
                  horizontal: getPropotionateScreenWidth(20)),
              child: DefaultButton(
                text: "Sprawdź",
                press: () {
                  final FirebaseAuth auth = FirebaseAuth.instance;
                  final User user = auth.currentUser;
                  String uid = user.uid;
                  FirebaseFirestore.instance
                      .collection("users")
                      .doc(uid)
                      .get()
                      .then((DocumentSnapshot documentSnapshot) {
                    if (documentSnapshot.exists) {
                      rental = documentSnapshot['rental'].toString();
                      ReservationService()
                          .getReservations(
                              rental,
                              _DatePickerState.selectedDate
                                  .toString()
                                  .split(" ")[0])
                          .then((QuerySnapshot docs) {
                        if (docs.docs.isNotEmpty) {
                          int i = 0;
                          index = docs.size - 1;
                          print(index);
                          while (i <= index) {
                            documents = docs.docs[i].data();
                            if (documents != null) {
                              reservations.insert(i, documents);
                              i++;
                              print(documents);
                            }
                          }
                        }
                      });
                    }
                  });
                  setState(() {
                    RentCard.name = documents['name'];
                    visibility = true;
                  });
                },
              ),
            ),
            SizedBox(
              height: getPropotionateScreenWidth(20),
            ),
            visibility == true
                ? new Padding(
                    padding: EdgeInsets.symmetric(
                        horizontal: getPropotionateScreenWidth(20)),
                    child: Column(
                      children: [
                        // ...List.generate(
                        //   documents2.length,
                        //   (index) => RentCard(reservations: reservations[0]),
                        // ),
                      ],
                    ),
                  )
                : new Text(
                    'Wybierz date i naciśnij przycisk aby sprawdzić rezerwacje!')
          ],
        ),
      ),
    );
  }
}

import'包：cloud_firestore/cloud_firestore.dart'；
导入“package:dinghy1/components/default_button.dart”；
导入“套餐：dinghy1/services/reservations.dart”；
导入“包：firebase_auth/firebase_auth.dart”；
进口“包装：颤振/材料.省道”；
导入“package:flatter_svg/flatter_svg.dart”；
导入“../../../constants.dart”；
导入“../../size_config.dart”；
类主体扩展了StatefulWidget{
@凌驾
_BodyState createState（）；
}
类_BodyState扩展了状态{
静态列表保留；
静态地图文档；
静态列表文档2；
静态整数指数；
布尔可见性=假；
字符串出租=ReservationService.rental；
@凌驾
小部件构建（构建上下文）{
返回SingleChildScrollView(
儿童：安全区(
子：列(
儿童：[
大小盒子(
高度：getPropotionateScreenWidth（20），
),
填充物(
填充：EdgeInsets.symmetric(
水平：getPropotionateScreenWidth（20）），
子：容器(
装饰：盒子装饰(
颜色：kPrimaryColor。不透明度（0.4），
边界半径：边界半径。圆形（30）），
高度：GetPromotionScreenHeight（75），
宽度：double.infinity，
儿童：中心(
子：文本(
“Sprawdźrezerwacje”，
样式：TextStyle(
fontSize:getPropotionateScreenWidth（20），
fontWeight:fontWeight.bold），
textAlign:textAlign.center，
),
),
),
),
大小盒子(
高度：getPropotionateScreenWidth（20），
),
日期选择器（），
大小盒子(
高度：getPropotionateScreenWidth（20），
),
填充物(
填充：EdgeInsets.symmetric(
水平：getPropotionateScreenWidth（20）），
子：默认按钮(
文本：“Sprawdź”，
新闻界：（）{
final FirebaseAuth auth=FirebaseAuth.instance；
最终用户=auth.currentUser；
字符串uid=user.uid；
FirebaseFirestore.instance
.收集（“用户”）
.doc（uid）
.get（）
.然后（（文档快照文档快照）{
if（documentSnapshot.exists）{
rental=documentSnapshot['rental'].toString（）；
ReservationService（）
.GetReserves(
租金
_DatePickerState.selectedDate
.toString（）
.split（“”[0]）
.然后（（QuerySnapshot文档）{
if（docs.docs.isNotEmpty）{
int i=0；
index=docs.size-1；
打印（索引）；
而（i）租赁卡（预订：预订[0]），
// ),
],
),
)
：新文本(
“Wybierz date i naciśnij przycisk aby sprawdzićrezerwacje！”）
],
),
),
);
}
}
下面是出错的代码示例

E/flutter ( 5082): [ERROR:flutter/lib/ui/ui_dart_state.cc(177)] Unhandled Exception: NoSuchMethodError: The method 'insert' was called on null.
E/flutter ( 5082): Receiver: null
E/flutter ( 5082): Tried calling: insert(0, _LinkedHashMap len:7)
E/flutter ( 5082): #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5)
E/flutter ( 5082): #1      _BodyState.build.<anonymous closure>.<anonymous closure>.<anonymous closure>
package:dinghy1/…/components/body.dart:89
E/flutter ( 5082): #2      _rootRunUnary (dart:async/zone.dart:1198:47)
E/flutter ( 5082): #3      _CustomZone.runUnary (dart:async/zone.dart:1100:19)
E/flutter ( 5082): #4      _FutureListener.handleValue (dart:async/future_impl.dart:143:18)
E/flutter ( 5082): #5      Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:696:45)
E/flutter ( 5082): #6      Future._propagateToListeners (dart:async/future_impl.dart:725:32)
E/flutter ( 5082): #7      Future._completeWithValue (dart:async/future_impl.dart:529:5)
E/flutter ( 5082): #8      _AsyncAwaitCompleter.complete (dart:async-patch/async_patch.dart:40:15)
E/flutter ( 5082): #9      _completeOnAsyncReturn (dart:async-patch/async_patch.dart:311:13)
E/flutter ( 5082): #10     Query.get (package:cloud_firestore/src/query.dart)
package:cloud_firestore/src/query.dart:1
E/flutter ( 5082): <asynchronous suspension>
E/flutter ( 5082): #11     ReservationService.getReservations
package:dinghy1/services/reservations.dart:19
E/flutter ( 5082): #12     _BodyState.build.<anonymous closure>.<anonymous closure>
package:dinghy1/…/components/body.dart:76
E/flutter ( 5082): #13     _rootRunUnary (dart:async/zone.dart:1198:47)
E/flutter ( 5082): #14     _CustomZone.runUnary (dart:async/zone.dart:1100:19)
E/flutter ( 5082): #15     _FutureListener.handleValue (dart:async/future_impl.dart:143:18)
E/flutter ( 5082): #16     Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:696:45)
E/flutter ( 5082): #17     Future._propagateToListeners (dart:async/future_impl.dart:725:32)
E/flutter ( 5082): #18     Future._completeWithValue (dart:async/future_impl.dart:529:5)
E/flutter ( 5082): #19     _AsyncAwaitCompleter.complete (dart:async-patch/async_patch.dart:40:15)
E/flutter ( 5082): #20     _completeOnAsyncReturn (dart:async-patch/async_patch.dart:311:13)
E/flutter ( 5082): #21     DocumentReference.get (package:cloud_firestore/src/document_reference.dart)
package:cloud_firestore/src/document_reference.dart:1
E/flutter ( 5082): <asynchronous suspension>
E/flutter ( 5082): #22     _BodyState.build.<anonymous closure>
package:dinghy1/…/components/body.dart:71
E/flutter ( 5082): #23     _InkResponseState._handleTap
package:flutter/…/material/ink_well.dart:993
E/flutter ( 5082): #24     _InkResponseState.build.<anonymous closure>
package:flutter/…/material/ink_well.dart:1111
E/flutter ( 5082): #25     GestureRecognizer.invokeCallback
package:flutter/…/gestures/recognizer.dart:183
E/flutter ( 5082): #26     TapGestureRecognizer.handleTapUp
package:flutter/…/gestures/tap.dart:598
E/flutter ( 5082): #27     BaseTapGestureRecognizer._checkUp
package:flutter/…/gestures/tap.dart:287
E/flutter ( 5082): #28     BaseTapGestureRecognizer.handlePrimaryPointer
package:flutter/…/gestures/tap.dart:222
E/flutter ( 5082): #29     PrimaryPointerGestureRecognizer.handleEvent
package:flutter/…/gestures/recognizer.dart:476
E/flutter ( 5082): #34     PointerRouter.route
package:flutter/…/gestures/pointer_router.dart:106
E/flutter ( 5082): #35     GestureBinding.handleEvent
package:flutter/…/gestures/binding.dart:358
E/flutter ( 5082): #36     GestureBinding.dispatchEvent
package:flutter/…/gestures/binding.dart:338
E/flutter ( 5082): #37     RendererBinding.dispatchEvent
package:flutter/…/rendering/binding.dart:267
E/flutter ( 5082): #38     GestureBinding._handlePointerEvent
package:flutter/…/gestures/binding.dart:295
E/flutter ( 5082): #39     GestureBinding._flushPointerEventQueue
package:flutter/…/gestures/binding.dart:240
E/flutter ( 5082): #40     GestureBinding._handlePointerDataPacket
package:flutter/…/gestures/binding.dart:213
E/flutter ( 5082): #41     _rootRunUnary (dart:async/zone.dart:1206:13)
E/flutter ( 5082): #42     _CustomZone.runUnary (dart:async/zone.dart:1100:19)
E/flutter ( 5082): #43     _CustomZone.runUnaryGuarded (dart:async/zone.dart:1005:7)
E/flutter ( 5082): #44     _invoke1 (dart:ui/hooks.dart:265:10)
E/flutter ( 5082): #45     _dispatchPointerDataPacket (dart:ui/hooks.dart:174:5)
E/flutter ( 5082):



E/flatter（5082）：[ERROR:flatter/lib/ui/ui\u dart\u state.cc（177）]未处理的异常：NoSuchMethodError:对null调用了方法“insert”。
E/颤振（5082）：接收器：空
E/flatter（5082）：尝试呼叫：插入（0，_linkedhashmaplen:7）
E/颤振（5082）：#0 Object.noSuchMethod（dart:core patch/Object_patch.dart:51:5）
E/颤振（5082）：#1#身体状态。构建。。。
包装：鼎海1/../components/body.省道：89
E/flatter（5082）：#2 rootrunnary（dart:async/zone.dart:1198:47）
E/flatter（5082）：#3_CustomZone.runUnary（dart:async/zone.dart:1100:19）
E/flatter（5082）：#4 FutureListener.handleValue（dart:async/future_impl.dart:143:18）
E/flatter（5082）：#5 Future._-propagateToListeners.handleValueCallback（dart:async/Future_-impl.dart:696:45）
E/flatter（5082）：#6未来。"传播给监听器（dart:async/Future\u impl.dart:725:32）
E/颤振（5082）：#7未来。_完成值（dart:async/Future\u impl.dart:529:5）
E/flatter（5082）：#8 AsyncAwaitCompleter.complete（dart:async patch/async patch.dart:40:15）
E/颤振（5082）：#9完成同步返回（dart:async patch/async patch.dart:311:13）
E/flatter（5082）：#10 Query.get（包：cloud_firestore/src/Query.dart）
包：cloud\u firestore/src/query.dart:1
E/颤振（5082）：
E/flatter（5082）：#11 ReservationService.getReservations
套餐：鼎海1号/服务/预订。dart:19
E/颤振（5082）：#12#身体状态。构建。。
包装：鼎海1/../components/body.省道：76
E/颤振（5082）：#13 35;根运行单位（dart:async/zone.dart:1198:47）
E/flatter（5082）：#14 _CustomZone.runUnary（dart:async/zone.dart:1100:19）
E/flatter（5082）：#15 FutureListener.handleValue（dart:async/future_impl.dart:143:18）
E/flatter（5082）：#16 Future._propagateToListeners.handleValueCallback（dart:async/Future_impl.dart:696:45）
E/flatter（5082）：#17未来。(dart:async/Future_impl.dart:725:32）
E/颤振（5082）：#18未来。_完成值（dart:async/Future\u impl.dart:529:5）
E/颤振（5082）：#19#完成器.compl

static List<Map<String, dynamic>> reservations = [];
static Map<String, dynamic> documents = {};
List<QueryDocumentSnapshot> documents2 = [];