Using a javascript parameter in a cshtml file to filter data in a datatable

Question

Using a javascript parameter in a cshtml file to filter data in a datatable

Here is the model code

public class viewCase
{
  public List<string> lstCategory   { get; set; }
  public DataTable dtWrkTsk { get; set; }
}

This is the controller code

string query = "SELECT WorkFlowID,Subject,Category FROM CMSTasksWorkFlow" 

objcase.dtWrkTsk   = objdataclas.ExecuteDataTable(query);

return View("../ViewCases/CasesScreen",objcase);

Below is the cshtml code snippet

 function getCaption() {

var cat=    $("#layout option:selected").text();  

var arr =  @Html.Raw(Newtonsoft.Json.JsonConvert.SerializeObject(
Model.dtWrkTsk.Select("Catagory='" + cat + "'") )); 
}

An error 'cat ' does not exist in current context' is encountered

If trying this approach

function getCaption() {

      var cat=    $("#layout option:selected").text();  
     var arr =  @Html.Raw(Newtonsoft.Json.JsonConvert.SerializeObject(
       Model.dtWrkTsk.Select("Catagory='" +@<text> cat </text> + "'") ));}

Error CS1660: Cannot convert lambda expression to type 'string' because it is not a delegate type

<div id="addTask" class="modal fade " aria-hidden="true">
        <div class="modal-dialog">
            <div class="modal-content round">
                <div class="modal-header"><h4>New Task </h4></div>
                <div id="tbody" class="modal-body" style="height:20%">
                    @Html.DropDownList("layout", Model.lstCategory.Select(m => new SelectListItem { Text = m, Value = m }), "All", new { onclick = "getCaption()" })
                    <div id="dtask" style="width: 80%; overflow: scroll; ">

                    </div>
                </div>
                <div class="modal-footer">
                    <button type="button" data-dismiss="modal" class="btn btn-primary"  >OK</button>
                    <button type="button" data-dismiss="modal" class="btn">Cancel</button>
                </div>
            </div>
        </div>
    </div>

The goal is to keep the datatable disconnected from the server. The getCaption() function is called whenever the user changes the value in the Html.DropDownList.

Only the select condition in the datatable needs to be updated based on the JavaScript variable being passed.

How can the JavaScript variable be passed in the datatable.select function?

javascript c#asp.net-mvc razor

Answer 1

Answer №1

When using @Html.Raw() in the code snippet var arr = @Html.Raw(...), it's important to note that this is razor code that gets processed on the server before being sent to the view. The code includes a query function .Select() which relies on a JavaScript variable that may not be in scope at that point.

To resolve this issue, you should assign the collection to a JavaScript variable and then filter the resulting array in JavaScript based on the selected option.

In the scenario where dtWrkTsk represents a collection of a model with a property string Category, and you want to filter the collection to only return objects whose Category value matches the selected option:

@Html.DropDownList("layout", Model.lstCategory.Select(m => new SelectListItem { Text = m, Value = m }), "All")

Alternatively:

@Html.DropDownList("layout", new SelectList(Model.lstCategory), "All")

<script>
    // Assign the collection to a JavaScript array
    var arr = @Html.Raw(Json.Encode(Model.dtWrkTsk))
    $('#layout').change(function() {
        var selectedCategory = $(this).val();
        // Filter the collection for matching objects
        var result = $(arr).filter(function(index, item) {
            return item.Category === selectedCategory;
        });
        .... // Perform actions with the results
    });
</script>

For further information, consider reading about Unobtrusive JavaScript.

Answer 2

When using @Html.Raw() in the code snippet var arr = @Html.Raw(...), it's important to note that this is razor code that gets processed on the server before being sent to the view. The code includes a query function .Select() which relies on a JavaScript variable that may not be in scope at that point.

To resolve this issue, you should assign the collection to a JavaScript variable and then filter the resulting array in JavaScript based on the selected option.

In the scenario where dtWrkTsk represents a collection of a model with a property string Category, and you want to filter the collection to only return objects whose Category value matches the selected option:

@Html.DropDownList("layout", Model.lstCategory.Select(m => new SelectListItem { Text = m, Value = m }), "All")

Alternatively:

@Html.DropDownList("layout", new SelectList(Model.lstCategory), "All")

<script>
    // Assign the collection to a JavaScript array
    var arr = @Html.Raw(Json.Encode(Model.dtWrkTsk))
    $('#layout').change(function() {
        var selectedCategory = $(this).val();
        // Filter the collection for matching objects
        var result = $(arr).filter(function(index, item) {
            return item.Category === selectedCategory;
        });
        .... // Perform actions with the results
    });
</script>

For further information, consider reading about Unobtrusive JavaScript.

Using a javascript parameter in a cshtml file to filter data in a datatable

Answer №1

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