Scott on Writing

# re: My Wife's First Contribution to 4Guys 11/23/2004 5:26 PM bestcomy

a really usefule control.
by the way,are your wife is a chinese? cause her name is Jisun Lee

# re: My Wife's First Contribution to 4Guys 11/23/2004 9:21 PM Scott Mitchell

She was born in South Korea, moved to the states when she was a toddler.

# re: My Wife's First Contribution to 4Guys 11/24/2004 8:40 AM Eric Madariaga

Nice control.

One can also handle this kind of problem with a regularexpressionvalidator by setting the validation expression.

e.g. If you want to limit the length of a textbox to 20 characters you could set:

validationexpression=".{0,20}"

# re: My Wife's First Contribution to 4Guys 11/28/2004 6:08 AM Guy Baron

Nice Control + Article,
However I would add another property that would let the consumer of the control declare how he would like an input that contains all white spaces be evaluated, and factor that in the validation routine.

# re: My Wife's First Contribution to 4Guys 11/28/2004 1:14 PM Rajeev Gopal

Wonderful!

But, to be honest, I would go Eric Madariga's way.

Hey, who can stop you creating controls? You are really a control freak :-)

# re: My Wife's First Contribution to 4Guys 11/29/2004 8:44 AM Michael

I guess you can't call it 4Guys anymore, eh?

# re: My Wife's First Contribution to 4Guys 12/2/2004 3:32 AM Gavin Lyons

Love regular expression too ..

But I like the example, it was helpful to understand how controls work.

I updated your control to sport mininum length too.

/// <summary>
/// TextBoxLengthValidator - orginal authored by Jisun Lee, extended to support mininum values by Gavin Lyons
/// </summary>
[ToolboxData("<{0}:TextBoxLengthValidator runat=server ErrorMessage=\"TextBoxLengthValidator\"></{0}:TextBoxLengthValidator>")]
public class TextBoxLengthValidator : BaseCompareValidator
{
/// <summary>
/// Specifies the maximum length of the TextBox the control is validating. If this value
/// is less than 0, then inputs of any length are considered valid.
/// </summary>
[Bindable(true),
Description("Specifies the maximum length of the TextBox the control is validating. If this value is less than 0, then inputs of any length are considered valid."),
Category("Behavior"),
DefaultValue(-1)]
public int MaximumLength
{
get
{
object MaxLengthVS = this.ViewState["MaximumLength"];
if (MaxLengthVS != null)
{
return (int) MaxLengthVS;
}
return -1;
}
set
{
this.ViewState["MaximumLength"] = value;
}
}
/// <summary>
/// Specifies the minimum length of the TextBox the control is validating. If this value
/// is less than 0, then inputs of any length are considered valid.
/// </summary>
[Bindable(true),
Description("Specifies the minimum length of the TextBox the control is validating. If this value is less than 0, then inputs of any length are considered valid."),
Category("Behavior"),
DefaultValue(-1)]
public int MinimumLength
{
get
{
object MinLengthVS = this.ViewState["MinimumLength"];
if (MinLengthVS != null)
{
return (int) MinLengthVS;
}
return -1;
}
set
{
this.ViewState["MinimumLength"] = value;
}
}
#region Overriden Methods
/// <summary>
/// Adds client-side functionality for uplevel browsers by specifying the JavaScript function
/// to call when validating, as well as a needed parameter (the MaximumLength property value).
/// </summary>
protected override void AddAttributesToRender(HtmlTextWriter writer)
{
base.AddAttributesToRender(writer);
if (base.RenderUplevel)
{
writer.AddAttribute("evaluationfunction", "TextBoxLengthValidatorIsValid");
writer.AddAttribute("maximumlength", this.MaximumLength.ToString());
writer.AddAttribute("minimumlength", this.MinimumLength.ToString());
}
}

/// <summary>
/// Checks to ensure that the ControlToValidate property is set to a TextBox
/// </summary>
protected override bool ControlPropertiesValid()
{
if (base.FindControl(base.GetControlRenderID(base.ControlToValidate)).GetType() != new System.Web.UI.WebControls.TextBox().GetType())
throw new HttpException("Control to Validate of must be a text box.");
return base.ControlPropertiesValid();
}

/// <summary>
/// Performs the server-side validation. If MaximumLength is less than 0, always returns True;
/// otherwise, returns True only if the ControlToValidate's length is less than or equal to the
/// specified MaximumLength.
/// </summary>
protected override bool EvaluateIsValid()
{
bool MaxLenForValidate = false;
bool MinLenForValidate = false;

string ControlToValidateName = base.GetControlValidationValue(base.ControlToValidate);

if (this.MaximumLength > 0) MaxLenForValidate = (ControlToValidateName.Length <= System.Convert.ToInt32(this.MaximumLength));
else MaxLenForValidate=true;

if (this.MinimumLength > 0) MinLenForValidate = (ControlToValidateName.Length >= System.Convert.ToInt32(this.MinimumLength));
else MinLenForValidate = true;

if (MinLenForValidate && MaxLenForValidate) return true;
else return false;
}

/// <summary>
/// Injects the JavaScript function that performs client-side validation for uplevel browsers.
/// </summary>
protected override void OnPreRender(EventArgs e)
{
base.OnPreRender(e);

if (base.RenderUplevel)
Page.RegisterClientScriptBlock("TxtBxLngthValIsValid",
@"<script language='javascript'>
function TextBoxLengthValidatorIsValid(val)
{var maxb=false;var minb=false;var value=ValidatorGetValue(val.controltovalidate);if (val.maximumlength>0) {if (value.length<=val.maximumlength) {maxb=true;} else {maxb=false;}} else {maxb=true};if (val.minimumlength>0) {if (value.length>=val.minimumlength) {minb=true;} else {minb=false;}} else {minb=true};if (maxb && minb) {return true;} else {return false;}}
</script>");
}
#endregion
}

# re: My Wife's First Contribution to 4Guys 9/26/2005 2:16 AM gavin

For user controls it will give an object reference error. Here's little workaround which is incomplete, if anyone wants to fill in the blanks.. :-)


protected override bool ControlPropertiesValid()
{
string CtrlToValName=base.ControlToValidate;
if (base.NamingContainer.ClientID!=null)
{
// User controls, Datagrid etc...

}
else
{
if (base.FindControl(base.GetControlRenderID(base.ControlToValidate)).GetType() != new System.Web.UI.WebControls.TextBox().GetType())
throw new HttpException("Control to Validate of must be a text box.");
}
return base.ControlPropertiesValid();
}