AngularJS-TypeError：使用下拉菜单时，无法读取未定义的属性“名称”

Question

 <select id="ddlPropertyName" ng-options="property.Name for property in allProperty" ng-model="property.Name"><option value="">-Select Name-</option>
                            </select>

If there no value selected in dropdown i'm getting below error :( TypeError: Cannot read property 'name' of undefined"

js code Name: $scope.property.Name.Name

But I want if no value gets selected still I can check undefined or null so that my Json can set value and code execute without execption

Answer 1

Use some other model variable instead of property . Here in the modified HTML I have used selectedProperty

<select id="ddlPropertyName" 
    ng-options="property.Name for property in allProperty" 
    ng-model="selectedProperty">
    <option value="">-Select Name-</option>
</select>

Note: You are using label for value in array in ngOption so selectedProperty will hold the property type

Answer 2

Below Code Works For Me

  <select ng-model="qid">
            <option value="">--Select--</option>
     <option ng-repeat="p in pollquestions" value="{{p.QId}}">{{p.QText}}</option>
 </select>

 app.controller("optionsCntrl", function ($scope, angularService) {
//$scope.optionsCntrl = [{ QId: 1, QText: "What is this 1?" }];
var getData = angularService.getQuestion();
getData.then(function (ques) {
    $scope.pollquestions = ques.data;
}, function () {
    alert('Error in getting records');
});
$scope.AddUpdatePollQuestionOption = function () {
    var pollquestionanswer = {
        qid:$scope.qid,
        anstext: $scope.anstext,
        anscount: 1
    };
    var getData = angularService.addPollQuestionOptions(pollquestionanswer).success(deferred.resolve).error(deferred.reject);
    getData.then(function (msg) {
        alert(msg.data);
    }, function () {
        alert('Error in adding record');
    });
}
});
 public string AddPollQuestionOptions(PollQuestionAnswer pollQuestionAnswer)
    {
        if (pollQuestionAnswer != null)
        {
            if (!String.IsNullOrEmpty(Convert.ToString(pollQuestionAnswer.qid)))
            {
                try
                {
                    using (DemoContext contextObj = new DemoContext())
                    {
                        contextObj.pollquestionanswer.Add(pollQuestionAnswer);
                        contextObj.SaveChanges();
                        return "Poll Question Answer Added";
                    }
                }
                catch (Exception objEx)
                {
                    return "Poll Question Not Found";
                }
            }
            else
            {
                return "Invalid Request";
            }
        }
        else
        {
            return "Invalid Record";
        }

    }

Answer 3

This error occurs basically when the fields specified by you in the Column Definition doesn't have name or the same column has been put twice in the Column Definition. Search for the similar column and remove one with the same name that will solve this error.

Answer 4

Just use below code in your controller

if($scope.property.Name !== null || $scope.property.Name !== undefined) {
    console.log('here');
}