Dart 角镖中的求值误差

我得到的评估错误如下所示，但我的程序中的一切都在工作秩序，所以我想知道为什么我得到这个？从堆栈跟踪中没有问题所在位置的指示

isChecked（field，value）

是一个函数，它返回一个布尔值，我在

ng model

属性中对该布尔值进行计算，该属性由

ng repeat

生成，约70个复选框。如果这是一个问题，任何帮助和建议都将不胜感激：）

---

这里的“alertFilter”是从服务中获得的。更新alertFilter时会触发错误-这会触发共享此筛选器的程序的其他4个部分进行更新。请注意，这些其他部分不更新alertFilter，它们仅从中读取。

请添加一些代码（

isChecked（）

和复选框的html）@GünterZöchbauer感谢您的回复。我已经用额外的代码更新了OP。isChecked中的alertFilter变量是通过从服务获取它的getter获得的，因为程序的多个部分共享此筛选器。我假设错误与此有关，但我仍然不明白为什么我的程序没有任何错误，尽管有错误。我认为添加的代码很好地演示了您正在做的事情，但我不知道为什么它会失败。

Eval Error: Cannot assign to isChecked(field, val) while evaling [isChecked(field, val)]

FROM:
#0      Expression.assign (package:angular/core/parser/syntax.dart:45:7)
#1      _UnwrapExceptionDecorator.assign (package:angular/core/parser/parser.dart:125:26)
#2      BoundExpression.assign (package:angular/core/parser/syntax.dart:60:41)
#3      NgModel.modelValue= (package:angular/directive/ng_model.dart:211:11)
#4      NgModel.viewValue= (package:angular/directive/ng_model.dart:200:5)
#5      InputCheckbox.InputCheckbox.<anonymous closure>.<anonymous closure> (package:angular/directive/ng_model.dart:318:19)
#6      NgModelOptions._runFuncDebounced (package:angular/directive/ng_model_options.dart:80:11)
#7      NgModelOptions.executeChangeFunc (package:angular/directive/ng_model_options.dart:68:20)
#8      InputCheckbox.InputCheckbox.<anonymous closure> (package:angular/directive/ng_model.dart:317:49)
#9      _rootRunUnary (dart:async/zone.dart:915)
#10     _ZoneDelegate.runUnary (dart:async/zone.dart:510)
#11     VmTurnZone._onRunUnary.<anonymous closure> (package:angular/core/zone.dart:122:55)
#12     VmTurnZone._onRunBase (package:angular/core/zone.dart:104:16)
#13     VmTurnZone._onRunUnary (package:angular/core/zone.dart:122:7)
#14     _CustomZone.runUnary (dart:async/zone.dart:811)
#15     _CustomZone.runUnaryGuarded (dart:async/zone.dart:717)
#16     _CustomZone.bindUnaryCallback.<anonymous closure> (dart:async/zone.dart:743)


STACKTRACE:
#0      _UnwrapExceptionDecorator.assign (package:angular/core/parser/parser.dart:127:7)
#1      BoundExpression.assign (package:angular/core/parser/syntax.dart:60:41)
#2      NgModel.modelValue= (package:angular/directive/ng_model.dart:211:11)
#3      NgModel.viewValue= (package:angular/directive/ng_model.dart:200:5)
#4      InputCheckbox.InputCheckbox.<anonymous closure>.<anonymous closure> (package:angular/directive/ng_model.dart:318:19)
#5      NgModelOptions._runFuncDebounced (package:angular/directive/ng_model_options.dart:80:11)
#6      NgModelOptions.executeChangeFunc (package:angular/directive/ng_model_options.dart:68:20)
#7      InputCheckbox.InputCheckbox.<anonymous closure> (package:angular/directive/ng_model.dart:317:49)
#8      _rootRunUnary (dart:async/zone.dart:915)
#9      _ZoneDelegate.runUnary (dart:async/zone.dart:510)
#10     VmTurnZone._onRunUnary.<anonymous closure> (package:angular/core/zone.dart:122:55)
#11     VmTurnZone._onRunBase (package:angular/core/zone.dart:104:16)
#12     VmTurnZone._onRunUnary (package:angular/core/zone.dart:122:7)
#13     _CustomZone.runUnary (dart:async/zone.dart:811)
#14     _CustomZone.runUnaryGuarded (dart:async/zone.dart:717)
#15     _CustomZone.bindUnaryCallback.<anonymous closure> (dart:async/zone.dart:743)

  <fieldset ng-repeat="field in $.filterFields">
      <legend>Filter by {{field}}</legend>
      <span ng-repeat="val in $.getValuesForField(field)">
          <label>{{val}}</label>
          <input type="checkbox" ng-click="$.checkboxClicked(field, val)" ng-model="isChecked(field, val)">
      </span>
  </fieldset>

bool isChecked(String key, String value){
    if(alertFilter.containsKey(key) && alertFilter[key].contains(value)) {
      return true;
    }
    else{
      return false;
    }
}