xVal with WebForms Part 2

Since my last post, I’ve completely rethought and re-implemented my take on xVal for WebForms. If you’re not familiar with xVal, stop now and read the tutorial. Now that you’re back, lets talk about xVal and WebForms.


This is the model we’ll be using (you should recognize it from the xVal tutorial):

public class Booking
    public string ClientName { get; set; }

    [Range(1, 20)]
    public int NumberOfGuests { get; set; }

    public DateTime ArrivalDate { get; set; }


And here is the form:

<asp:ValidationSummary ID="valSummary" runat="server" />
<label for="txtClientName">
  Your name:
<asp:TextBox ID="txtClientName" runat="server" />
<label for="txtNumberOfGuests">
  Number of guests:
<asp:TextBox ID="txtNumberOfGuests" runat="server" />
<label for="txtArrivalDate">
  Arrival date:
<asp:TextBox ID="txtArrivalDate" runat="server" />
<asp:Button ID="btnSubmit" runat="server" Text="Submit" OnClick="btnSubmit_Click" />


My first try at validation was adding a validator control for each input field. After playing with it a bit, I decided that it would be better to have one validator for the entire model. This control defines the model’s type (ModelType), and then maps each property (PropertyName) to an input control (ControlToValidate).

<val:ModelValidator ID="valBooking" runat="server" ModelType="xVal.WebForms.Demo.Booking, xVal.WebForms.Demo">
    <val:ModelProperty PropertyName="ClientName" ControlToValidate="txtClientName" />
    <val:ModelProperty PropertyName="NumberOfGuests" ControlToValidate="txtNumberOfGuests" />
    <val:ModelProperty PropertyName="ArrivalDate" ControlToValidate="txtArrivalDate" />


The biggest challenge was figuring out how to reference the input controls by given ID instead of by the elementPrefix + PropertyName convention. In other words, MVC xVal assumes that your ClientName input control ID is booking.ClientName, where booking is the elementPrefix and ClientName is the name of the property. This doesn’t work out so well with web forms and generated IDs. I got around this with the ModelProperties collection of ModelValidator. Then I updated the json formatted rule script to include each property’s control ID.

Complete Source and Demo

Get the complete source (with Bookings demo) at the xVal.WebForms project page on CodePlex.

John Rummell

Read more posts by this author.