从视图的javascript向控制器发送参数（不能为null） [英] Send a parameter (cannot be null) to the controller from the javascript of the view

问题描述

在更改视图中的下拉列表时调用以下函数 GetProject 。



Javascript

The following function GetProject is called on change of the dropdown in the view.

Javascript

<script>
    function GetProject(projId) {
        
        var selectedText = projId.options[projId.selectedIndex].innerHTML;

        var selectedValue = projId.value;
        
        var url = '@Url.Action("OpenEndedDetails", "ResponseController", new { @projId = "projId" }, null);
        url = url.replace('projId', encodeURIComponent(selectedValue));

        alert(url);
        window.location.href = url;
    }

</script>

ResponseController

ResponseController

public ActionResult OpenEndedDetails(int projId)
        {
            
            ResponseContext feedback = new ResponseContext();
           
            /* Conditions:
             * @All openended questions in a project
             * */
            List<Response> feedbacks = feedback.Responses.Where(resp => resp.Answer.Equals("0") && resp.ProjectID == projId).ToList();

            return View(feedbacks);
        }

错误：

参数字典包含参数'projId'的空条目对于'SmartAdminMvc.Controllers.ResponseController'中方法'System.Web.Mvc.ActionResult OpenEndedDetails（Int32）'的非可空类型'System.Int32'。可选参数必须是引用类型，可以为空的类型，或者声明为可选参数。

参数名称：参数





ProjId 是int类型的主键。我不知道如何摆脱这种异常。我希望Url.Action加载我的整个视图，以及从下拉列表中传递的值。

我可能在代码中犯了一些重大错误。请更正。

请帮助我，因为我长期坚持这个问题。

谢谢

Error:
The parameters dictionary contains a null entry for parameter 'projId' of non-nullable type 'System.Int32' for method 'System.Web.Mvc.ActionResult OpenEndedDetails(Int32)' in 'SmartAdminMvc.Controllers.ResponseController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter.
Parameter name: parameters


ProjId is a primary key of type int. I don't know how to get rid of this exception. I want the Url.Action to load my entire view, with the value that i pass from the dropdown.
I might have made some major blunders with code. Kindly correct it.
Please help me as i am stuck with this issue for long.
Thanks

推荐答案

Check whether value is null before assigning it to selectedValue
to check whether value is null refer this

http://stackoverflow.com/questions/6003884/如何在javascript中检查空值 - [ ^ ]

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