Finding markup in order to validate - ASP.NET

I have a form. I need to validate two input fields in this form. I'm having trouble because the code that was written has an odd way of displaying markup. When the user clicks submit and the input field is empty, I want a check to be made that displays that the user must input a value before submitting. I'm also unfamiliar with how .NET is structured. The forms are in the Model.FormData - when I console log it I get this -

1[ViewModels.data.dataFormFieldViewModel]

The forms I am looking for are not displayed below. That is all the evidence I have. The question is where can I go to find the markup for these input fields? Where are they typically located in a .NET project? I can't seem to find any evidence they are in any other cshtml files. Thanks

cshtml

@for (var count = 0; count < Model.FormData.Count; count++)
            {

                if (count == 2)
                 {
                     <div class="form-group">
                         <label asp-for="Date" class="control-label">Date Of Trip</label>
                         <div class="input-group filter-input datepicker">
                             <input asp-for="Date" class="form-control" type="date"/>
                             <span class="input-group-addon">
                                 <span class="glyphicon glyphicon-calendar"></span>
                             </span>
                         </div>
                         <span asp-validation-for="Date" class="text-danger"></span>
                         <span asp-validation-for="Description" class="text-danger"></span>
                     </div>
                 }

                if (count == 11)
                 {
                     <div class="form-group">
                         <label class="control-label">Attachments</label>
                         <input type="file" name="files" class="input-group" multiple="multiple" />
                     </div>
                 }

                if (count == 13)
                {
                    <hr style="background:#FFFFFF; border:0; height:7px" />
                }

                if (count == 14)
                 {
                     <div class="form-group">
                         <label asp-for="SelectedPriority" class="control-label  ">Priority</label>
                         <select asp-for="SelectedPriority" asp-items="@Model.Priorities" class="form-control 1 "></select>
                         <span asp-validation-for="SelectedPriority" class="text-danger"></span>
                     </div>
                     <div class="form-group">
                         <label asp-for="Cost" class="control-label  "></label>
                         <div class="input-group filter-input">
                             <span class="input-group-addon">$</span>
                             <input asp-for="Cost" class="form-control currency" placeholder="0.00"/>
                         </div>
                         <span asp-validation-for="Cost" class="text-danger"></span>
                     </div>
                 }

                var fieldType = Model.FormData[count].HtmlFieldType;

                <div class="form-group">
                    <!--hide label if type is checkbox-->
                    @if (!Model.FormData[count].Type.Equals(FieldType.Checkbox))
                    {
                        <label asp-for="@Model.FormData[count].Name" class="control-label  ">@Model.FormData[count].Name</label>
                    }

                    <!--hidden fields to maintain model data-->
                    <input asp-for="FormData[count].Type" class="hidden"/>
                    <input asp-for="FormData[count].AllowedValues" class="hidden"/>
                    <input asp-for="FormData[count].Name" class="hidden" value="@Model.FormData[count].Name"/>

                    @if (Model.FormData[count].Type.Equals(FieldType.Checkbox))
                    {
                        <div class="checkbox-inline">
                            <label>
                                <input asp-for="FormData[count].CheckboxValue" type="checkbox"/>@Model.FormData[count].Name</label>
                        </div>
                    }
                    else if (Model.FormData[count].Type.Equals(FieldType.Combobox))
                    {
                        <select asp-for="FormData[count].Value" asp-items="@Model.FormData[count].AllowedValues" class="form-control" asp-selected-item=""></select>
                    }
                    else if (Model.FormData[count].Type.Equals(FieldType.Label))
                    {
                        <div>@Model.FormData[count].Value</div>
                        <input asp-for="FormData[count].Value" class="hidden" value="@Model.FormData[count].Value"/>
                    }
                    else if (Model.FormData[count].Type.Equals(FieldType.Double))
                    {
                        <input asp-for="FormData[count].Value" type="number"
                               class="form-control" step="any"/>
                    }
                    else if (Model.FormData[count].Type.Equals(FieldType.Date))
                    {
                        <div class="input-group filter-input datepicker">
                            <input asp-for="FormData[count].Value" class="form-control date-input" type="date"/>
                            <span class="input-group-addon">
                                <span class="glyphicon glyphicon-calendar"></span>
                            </span>
                        </div>
                    }
                    else
                    {
                        <input asp-for="FormData[count].Value" type="@fieldType"
                               class="form-control 1 "/>
                    }
                </div>
            }