ASP.NET RangeValidator weirdness with MaximumValue

Question

I have a pretty simple ASP.NET page with some input fields and validators. A single field accepting a double is as follows:

<asp:TextBox ID="tbHeight" runat="server" /> <asp:RangeValidator ID="vdHeight" runat="server" ErrorMessage="Height must be a positive number" Text="*" ControlToValidate="tbHeight" MinimumValue="0" Type="Double" /> 

This works as expected, and the user must enter a number> = 0.
Update: this does not work properly (some strange errors in the project). See comments for answers below for more details.

Then I will try the same for a field accepting an integer:

 <asp:TextBox ID="tbGrossTonnage" runat="server" /> <asp:RangeValidator ID="vdGrossTonnage" runat="server" ErrorMessage="Gross Tonnage must be a positive whole number" Text="*" ControlToValidate="tbGrossTonnage" MinimumValue="0" Type="Integer" /> 

When loading the ASP page, this gives me the following error: the value of the '' MaximumValue property for 'vdGrossTonnage' cannot be converted to an Integer type.

I do not have any specific requirements for the maximum value in the system, so I would just like the default for Int32.MaxValue (although I would have to enter 2,147,483,647, since MaximumValue does not seem to accept the Int32.MaxValue constant).

Why RangeValidator t RangeValidator type Integer not accept the missing MaximumValue property, but is it normal for one of the Double types?

Answer 1

The MinimumValue and MaximumValue properties of the MinimumValue class return string.Empty as their default value, if not set.

Further, it also happens that the protected Convert() method implemented by BaseCompareValidator , which is used to convert string properties to values, calls int.Parse() for the case of ValidationDataType.Integer . int.Parse() does not like an empty string and throws an exception.

But, in the case of ValidationDataType.Double , Convert() first calls another protected method, ConvertDouble() (instead of double.Parse() ), and in this method it explicitly returns the string value “0” when an empty string is detected , and this is a string the value "0" is later parsed, via double.Parse() at 0d .

The Integer case does not use such a mapping from string.Empty to "0".

Consequently, drowsiness. The devil is in the details, and Reflector is your friend.

Answer 2

Leaving the MaximumValue field in Type = "Double" is equivalent to setting MaximumValue to 0. I’m not sure that you are correct that the first of your examples is working fine.

Answer 3

It is best to specify the MaximumValue for the RangeValidator , even if your requirements do not specifically require this. In this case, use MaxValue for Type . The default value for MaximumValue is String.Empty .

Answer 4

Just to make it more confusing ..

In my view of the form (which is in the update, if that matters) I have.

 <div class="Width100PercentPadded"> <div class="Width40PercentPadded FloatLeft ClearLeft"> Latitude: </div> <div class="Width60PercentPadded FloatLeft"> <asp:TextBox runat="server" ID="txtLatitude" CssClass="Width100Percent" Text='<%# Bind("Latitude") %>' ></asp:TextBox> <asp:CompareValidator ID="CompareValidatorLatitude" runat="server" ControlToValidate="txtLatitude" Operator="DataTypeCheck" Type="Double" ErrorMessage="Latitude must be numeric" Text="must be numeric" ForeColor="Red" Display="Dynamic"></asp:CompareValidator> <asp:RangeValidator ID="RangeValidatorLatitude" runat="server" ControlToValidate="txtLatitude" MinimumValue="0" MaximumValue="90" ErrorMessage="Latitude in range 0 to 90" Text="range 0 to 90" ForeColor="Red" Display="Dynamic"></asp:RangeValidator> </div> </div> <div class="Width100PercentPadded"> <div class="Width40PercentPadded FloatLeft ClearLeft"> Longitude: </div> <div class="Width60PercentPadded FloatLeft"> <asp:TextBox runat="server" ID="txtLongitude" CssClass="Width100Percent" Text='<%# Bind("Longitude") %>'></asp:TextBox> <asp:CompareValidator ID="CompareValidatorLongitude" runat="server" ControlToValidate="txtLongitude" Operator="DataTypeCheck" Type="Double" ErrorMessage="Longitude must be numeric" Text="must be numeric" ForeColor="Red" Display="Dynamic"></asp:CompareValidator> <asp:RangeValidator ID="RangeValidatorLongitude" runat="server" ControlToValidate="txtLongitude" MinimumValue="0" MaximumValue="180" ErrorMessage="Longitude in range 0 to 180" Text="range 0 to 180" ForeColor="Red" Display="Dynamic"></asp:RangeValidator> </div> </div> 

Please note that my validation for latitude and longitude is almost the same, except that Longitude allows you to get a higher max value.

At startup, the longitude is checked exactly as expected - the type must be numeric, and the value must be between 0 and 180.

The type of the Locator must be numeric, and the range is reset if the value is negative, but the value of maxvalue is not checked. I can put millions in the text box, and the validation is not interrupted.