Firebase 未处理的异常：类型'；字符串'；不是类型为'；num'；

大家好，我有一个用户应用程序和管理员应用程序，在用户应用程序中，我提供了一个名为promocode的选项，为此我在数据库中创建了两个promocodes。当我应用这些程序时，它工作正常，但当我从管理员应用程序添加新的promocode时，它出现了一个错误。有人能帮助我吗

这是我的密码：

if (passengers != null && passengers != 0) {
      total = ticketprice * passengers;
    }
    if (promoCode != null && promoCode.isNotEmpty) {
      _firestore
          .collection('promo_codes')
          .where('promo_code', isEqualTo: promoCode)
          .getDocuments()
          .then((QuerySnapshot data) {
        if (data != null && data.documents.length > 0) {
          var documentData = data.documents[0];

          if (documentData['price_reduction'] != null) {
            setState(() {
              total -= int.parse(documentData['price_reduction']);
            });
          } else if (documentData['percentage_reduction'] != null) {
            setState(() {
              total -= (total * int.parse(documentData['percentage_reduction']));
            });
          }

          setState(() {
            grandTotal = total;
          });
        }
      });
    }

我只添加了promocode的主代码，如果有人想查看，我将共享整个代码

这是我的错误：

════════ Exception caught by foundation library ════════════════════════════════════════════════════
The following FormatException was thrown while dispatching notifications for TextEditingController:
Invalid number (at character 1)

^

When the exception was thrown, this was the stack: 
#0      int._throwFormatException (dart:core-patch/integers_patch.dart:131:7)
#1      int.parse (dart:core-patch/integers_patch.dart:55:14)
#2      _MyAppState.testListener.<anonymous closure> (package:fire/main.dart:136:24)
#3      State.setState (package:flutter/src/widgets/framework.dart:1148:30)
#4      _MyAppState.testListener (package:fire/main.dart:130:5)
...
The TextEditingController sending notification was: TextEditingController#1dc24(TextEditingValue(text: ┤├, selection: TextSelection(baseOffset: 0, extentOffset: 0, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1)))
════════════════════════════════════════════════════════════════════════════════════════════════════
E/flutter (14220): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: type 'String' is not a subtype of type 'num'
E/flutter (14220): #0      _MyAppState._onChanged.<anonymous closure>.<anonymous closure> (package:fire/main.dart:109:36)
E/flutter (14220): #1      State.setState (package:flutter/src/widgets/framework.dart:1148:30)
E/flutter (14220): #2      _MyAppState._onChanged.<anonymous closure> (package:fire/main.dart:108:13)
E/flutter (14220): #3      _rootRunUnary (dart:async/zone.dart:1134:38)
E/flutter (14220): #4      _CustomZone.runUnary (dart:async/zone.dart:1031:19)
E/flutter (14220): #5      _FutureListener.handleValue (dart:async/future_impl.dart:140:18)
E/flutter (14220): #6      Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:682:45)
E/flutter (14220): #7      Future._propagateToListeners (dart:async/future_impl.dart:711:32)
E/flutter (14220): #8      Future._completeWithValue (dart:async/future_impl.dart:526:5)
E/flutter (14220): #9      _AsyncAwaitCompleter.complete (dart:async-patch/async_patch.dart:33:15)
E/flutter (14220): #10     _completeOnAsyncReturn (dart:async-patch/async_patch.dart:291:13)
E/flutter (14220): #11     Query.getDocuments (package:cloud_firestore/src/query.dart)
E/flutter (14220): <asynchronous suspension>
E/flutter (14220): #12     _MyAppState._onChanged (package:fire/main.dart:102:12)
E/flutter (14220): #13     _MyAppState.build.<anonymous closure> (package:fire/main.dart:559:33)
E/flutter (14220): #14     EditableTextState._formatAndSetValue (package:flutter/src/widgets/editable_text.dart:1607:14)
E/flutter (14220): #15     EditableTextState.updateEditingValue (package:flutter/src/widgets/editable_text.dart:1208:5)
E/flutter (14220): #16     TextInput._handleTextInputInvocation (package:flutter/src/services/text_input.dart:962:36)
E/flutter (14220): #17     MethodChannel._handleAsMethodCall (package:flutter/src/services/platform_channel.dart:402:55)
E/flutter (14220): #18     MethodChannel.setMethodCallHandler.<anonymous closure> (package:flutter/src/services/platform_channel.dart:370:54)
E/flutter (14220): #19     _DefaultBinaryMessenger.handlePlatformMessage (package:flutter/src/services/binding.dart:200:33)
E/flutter (14220): #20     _invoke3.<anonymous closure> (dart:ui/hooks.dart:303:15)
E/flutter (14220): #21     _rootRun (dart:async/zone.dart:1126:13)
E/flutter (14220): #22     _CustomZone.run (dart:async/zone.dart:1023:19)
E/flutter (14220): #23     _CustomZone.runGuarded (dart:async/zone.dart:925:7)
E/flutter (14220): #24     _invoke3 (dart:ui/hooks.dart:302:10)
E/flutter (14220): #25     _dispatchPlatformMessage (dart:ui/hooks.dart:162:5)
E/flutter (14220): 
E/flutter (14220): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: type 'String' is not a subtype of type 'num'
E/flutter (14220): #0      _MyAppState._onChanged.<anonymous closure>.<anonymous closure> (package:fire/main.dart:109:36)
E/flutter (14220): #1      State.setState (package:flutter/src/widgets/framework.dart:1148:30)
E/flutter (14220): #2      _MyAppState._onChanged.<anonymous closure> (package:fire/main.dart:108:13)
E/flutter (14220): #3      _rootRunUnary (dart:async/zone.dart:1134:38)
E/flutter (14220): #4      _CustomZone.runUnary (dart:async/zone.dart:1031:19)
E/flutter (14220): #5      _FutureListener.handleValue (dart:async/future_impl.dart:140:18)
E/flutter (14220): #6      Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:682:45)
E/flutter (14220): #7      Future._propagateToListeners (dart:async/future_impl.dart:711:32)
E/flutter (14220): #8      Future._completeWithValue (dart:async/future_impl.dart:526:5)
E/flutter (14220): #9      _AsyncAwaitCompleter.complete (dart:async-patch/async_patch.dart:33:15)
E/flutter (14220): #10     _completeOnAsyncReturn (dart:async-patch/async_patch.dart:291:13)
E/flutter (14220): #11     Query.getDocuments (package:cloud_firestore/src/query.dart)
E/flutter (14220): <asynchronous suspension>
E/flutter (14220): #12     _MyAppState._onChanged (package:fire/main.dart:102:12)
E/flutter (14220): #13     _MyAppState.build.<anonymous closure> (package:fire/main.dart:559:33)
E/flutter (14220): #14     EditableTextState._formatAndSetValue (package:flutter/src/widgets/editable_text.dart:1607:14)
E/flutter (14220): #15     EditableTextState.updateEditingValue (package:flutter/src/widgets/editable_text.dart:1208:5)
E/flutter (14220): #16     TextInput._handleTextInputInvocation (package:flutter/src/services/text_input.dart:962:36)
E/flutter (14220): #17     MethodChannel._handleAsMethodCall (package:flutter/src/services/platform_channel.dart:402:55)
E/flutter (14220): #18     MethodChannel.setMethodCallHandler.<anonymous closure> (package:flutter/src/services/platform_channel.dart:370:54)
E/flutter (14220): #19     _DefaultBinaryMessenger.handlePlatformMessage (package:flutter/src/services/binding.dart:200:33)
E/flutter (14220): #20     _invoke3.<anonymous closure> (dart:ui/hooks.dart:303:15)
E/flutter (14220): #21     _rootRun (dart:async/zone.dart:1126:13)
E/flutter (14220): #22     _CustomZone.run (dart:async/zone.dart:1023:19)
E/flutter (14220): #23     _CustomZone.runGuarded (dart:async/zone.dart:925:7)
E/flutter (14220): #24     _invoke3 (dart:ui/hooks.dart:302:10)
E/flutter (14220): #25     _dispatchPlatformMessage (dart:ui/hooks.dart:162:5)
E/flutter (14220): 
I/flutter (14220): false
I/chatty  (14220): uid=10288(m20zero.fire) Thread-3 identical 2 lines
I/flutter (14220): false

════════ 基金会例外════════════════════════════════════════════════════
为TextEditingController发送通知时引发以下FormatException：
无效数字（在字符1处）
^
引发异常时，这是堆栈：
#0 int.\u throwFormatException（dart:core patch/integers\u patch.dart:131:7）
#1 int.parse（dart:core patch/integers\u patch.dart:55:14）
#2_MyAppState.testListener。（包装：消防/主要。省道：136:24）
#3 State.setState（包：flatter/src/widgets/framework.dart:1148:30）
#4_MyAppState.testListener（包：fire/main.dart:130:5）
...
发送通知的TextEditingController为：TextEditingController#1dc24（TextEditingValue（文本：┤├, 选择：TextSelection（baseOffset:0，extendtoffset:0，affinity:textfaffinity.down，isDirectional:false），组合：TextRange（开始：-1，结束：-1）））
════════════════════════════════════════════════════════════════════════════════════════════════════
E/flatter（14220）：[错误：flatter/lib/ui/ui\u dart\u state.cc（157）]未处理的异常：类型“String”不是类型“num”的子类型
E/颤振（14220）：#0#MyAppState.#一旦更改。。（包装：消防/主要。省道：109:36）
E/flatter（14220）：#1 State.setState（包：flatter/src/widgets/framework.dart:1148:30）
E/颤振（14220）：#2#MyAppState.#一次更改。（包装：消防/主要。省道：108:13）
E/颤振（14220）：#3 RootRunnary（dart:async/zone.dart:1134:38）
E/flatter（14220）：#4_CustomZone.runUnary（dart:async/zone.dart:1031:19）
E/flatter（14220）：#5 FutureListener.handleValue（dart:async/future_impl.dart:140:18）
E/flatter（14220）：#6 Future._-propagateToListeners.handleValueCallback（dart:async/Future_-impl.dart:682:45）
E/flatter（14220）：#7未来。(dart:async/Future\u impl.dart:711:32）
E/颤振（14220）：#8未来。_完成值（dart:async/Future_impl.dart:526:5）
E/flatter（14220）：#9 AsyncAwaitCompleter.complete（dart:async patch/async patch.dart:33:15）
E/颤振（14220）：#10#完成同步返回（dart:async patch/async patch.dart:291:13）
E/flatter（14220）：#11 Query.getDocuments（包：cloud_firestore/src/Query.dart）
E/颤振（14220）：
E/颤振（14220）：#12(我的应用状态.)一旦改变（包：火/主。dart:102:12）
E/颤振（14220）：#13_MyAppState.build。（包装：消防/主要。省道：559:33）
E/flatter（14220）：#14 EditableTextState.(格式和设置值（包：flatter/src/widgets/EditableText.dart:1607:14）
E/flatter（14220）：#15 EditableTextState.updateEditingValue（包：flatter/src/widgets/EditableText.dart:1208:5）
电子/颤振（14220）：#16文本输入。#手工输入职业（包：颤振/src/services/text#u输入。dart:962:36）
电子/颤振（14220）：#17方法频道。_handleAsMethodCall（套餐：颤振/src/services/platform_频道。dart:402:55）
E/颤振（14220）：#18 MethodChannel.setMethodCallHandler。（包装：颤振/src/服务/平台通道。dart:370:54）
E/flatter（14220）：#19_DefaultBinaryMessenger.handlePlatformMessage（包：flatter/src/services/binding.dart:200:33）
E/颤振（14220）：20。（省道：用户界面/挂钩。省道：303:15）
E/颤振（14220）：#21 rootRun（dart:async/zone.dart:1126:13）
E/flatter（14220）：#22 _CustomZone.run（dart:async/zone.dart:1023:19）
E/颤振（14220）：#23 CustomZone.runguard（dart:async/zone.dart:925:7）
E/颤振（14220）：#24 _调用3（省道：ui/挂钩。省道：302:10）
E/flatter（14220）：#25 dispatchPlatformMessage（dart:ui/hooks.dart:162:5）
E/颤振（14220）：
E/flatter（14220）：[错误：flatter/lib/ui/ui\u dart\u state.cc（157）]未处理的异常：类型“String”不是类型“num”的子类型
E/颤振（14220）：#0#MyAppState.#一旦更改。。（包装：消防/主要。省道：109:36）
E/flatter（14220）：#1 State.setState（包：flatter/src/widgets/framework.dart:1148:30）
E/颤振（14220）：#2#MyAppState.#一次更改。（包装：消防/主要。省道：108:13）
E/颤振（14220）：#3 RootRunnary（dart:async/zone.dart:1134:38）
E/flatter（14220）：#4_CustomZone.runUnary（dart:async/zone.dart:1031:19）
E/flatter（14220）：#5 FutureListener.handleValue（dart:async/future_impl.dart:140:18）
E/flatter（14220）：#6 Future._-propagateToListeners.handleValueCallback（dart:async/Future_-impl.dart:682:45）
E/flatter（14220）：#7未来。(dart:async/Future\u impl.dart:711:32）
E/颤振（14220）：#8未来。_完成值（dart:async/Future_impl.dart:526:5）
E/flatter（14220）：#9 AsyncAwaitCompleter.complete（dart:async patch/async patch.dart:33:15）
E/颤振（14220）：#10#完成同步返回（dart:async patch/async patch.dart:291:13）
E/flatter（14220）：#11 Query.getDocuments（包：cloud_firestore/src/Query.dart）
E/颤振（14220）：
E/颤振（14220）：#12(我的应用状态.)一旦改变（包：火/主。dart:102:12）
E/颤振（14220）：#13_MyAppState.build。（包装：消防/主要。省道：559:33）
E/flatter（14220）：#14 EditableTextState.(格式和设置值（包：flatter/src/widgets/EditableText.dart:1607:14）
E/颤振（14220）：#15 EditableTextState.updateEditingValue
int.tryParse(documentData['price_reduction']);

int.tryParse(documentData['price_reduction']) ?? 0;

int.parse(documentData['price_reduction']);