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ASP.NET Core DropDownList in Razor Pages

Razor Pages is an alternative to the MVC pattern that makes page-focused coding easier and more productive. This approach consists of a cshtml file and a cshtml.cs file (by design, the two files have the same name). You can seamlessly integrate the Telerik UI DropDownList for ASP.NET Core in Razor Pages applications. This article describeshow to configure the DropDownList component in a Razor Pages scenario. For the complete project, refer to the DropDownList in Razor Pages example.

Getting Started

In order to set up the Razor DropDownList component bindings, you need to configure the Read method of its DataSource instance. The URL in this method should refer the name of the method in the PageModel. In this method, you can also pass additional parameters, such as filter string and antiforgery token (see dataFunction).

Razor

```csthml HtmlHelper    

    @(Html.Kendo().DropDownList()
            .Name("products")
            .DataTextField("ShipName")
            .DataValueField("ShipCity")
            .HtmlAttributes(new { style = "width:300px;" })
            .AutoBind(false)
            .Filter(FilterType.Contains)      
            .DataSource(ds => ds
                .Custom()
                .Transport(transport => transport
                    .Read(read => read
                        .Url("/DropDownList/DropDownListCrudOps?handler=Read").Data("dataFunction")
                    ))
                    .ServerFiltering(true)
            )
    )
```
```Razor TagHelper

    <kendo-dropdownlist name="products"
                        datatextfield="ShipName"
                        datavaluefield="ShipCity"
                        auto-bind="false"
                        filter="FilterType.Contains">
        <datasource server-filtering="true">
            <transport>
                <read url="@Url("/DropDownList/DropDownListCrudOps?handler=Read")" data="dataFunction" />
            </transport>
        </datasource>
    </kendo-dropdownlist>
```

Add an AntiForgeryToken at the top of the page.

Razor

    @inject Microsoft.AspNetCore.Antiforgery.IAntiforgery Xsrf
    @Html.AntiForgeryToken()

Send the AntiForgeryToken with the [Read, Create, Update, Destroy] request.

Razor

    <script>
        function forgeryToken() {
            return kendo.antiForgeryTokens();
        }
    </script>

Additional parameters can also be supplied.

Razor

    <script>
        function dataFunction() {
            var value = $("#products").getKendoDropDownList().filterInput.val();
            return {
                __RequestVerificationToken: kendo.antiForgeryTokens().__RequestVerificationToken,
                filterValue: value
            };
        }   
    </script>

Within the cshtml.cs file, add a handler method for the Read operation that returns the dataset.

cshtml.cs

    public JsonResult OnGetRead(string filterValue)
    {
        if (filterValue != null)
        {
            //orders is the DBContext
            var filteredData = orders.Where(p => p.ShipName.Contains(filterValue)); 
            return new JsonResult(filteredData);
        }
        return new JsonResult(orders);
    }

Declare the PageModel at the top of the page.
C#
```
    @page
    @model IndexModel
```

Bind the DropDownList to the property using the DropDownListFor() configuration.

HtmlHelper_Index.cshtml
    @page
    @model IndexModel

    @inject Microsoft.AspNetCore.Antiforgery.IAntiforgery Xsrf
    @Html.AntiForgeryToken()

    @(Html.Kendo().DropDownListFor(m => m.Product))
TagHelper_Index.cshtml
    @page
    @model IndexModel

    @inject Microsoft.AspNetCore.Antiforgery.IAntiforgery Xsrf
    @Html.AntiForgeryToken()
    @addTagHelper *, Kendo.Mvc

    <kendo-dropdownlist for="Product">
    </kendo-datepicker>

ASP.NET Core DropDownList in Razor Pages

Getting Started

See Also