C# – validation control unable to find its control to validate

asp.netccustom-controlsvalidation

i have a repeater that is bound to a number of custom dataitems/types

on the itemdatabound event for the repeater the code calls a renderedit function that depending on the custom datatype will render a custom control. it will also (if validation flag is set) render a validation control for the appropriate rendered edit control

the edit control overrides the CreateChildControls() method for the custom control adding a number of literalControls thus

protected override void CreateChildControls()
{
    //other bits removed - but it is this 'hidden' control i am trying to validate
    this.Controls.Add(new LiteralControl(string.Format(
                                         "<input type=\"text\" name=\"{0}\" id=\"{0}\" value=\"{1}\" style=\"display:none;\" \">"
                                         , this.UniqueID
                                         , this.MediaId.ToString())
                                         ));
    //some other bits removed
}

the validation control is rendered like this: where the passed in editcontrol is the control instance of which the above createchildcontrols is a method of..

public override Control RenderValidationControl(Control editControl)
{
    Control ctrl = new PlaceHolder();

    RequiredFieldValidator req = new RequiredFieldValidator();
    req.ID = editControl.ClientID + "_validator";
    req.ControlToValidate = editControl.UniqueID;
    req.Display = ValidatorDisplay.Dynamic;
    req.InitialValue = "0";
    req.ErrorMessage = this.Caption + " cannot be blank";
    ctrl.Controls.Add(req);

    return ctrl;
}

the problem is, altho the validation controls .ControlToValidate property is set to the uniqueid of the editcontrol.
when i hit the page i get the following error:
Unable to find control id 'FieldRepeater$ctl01$ctl00' referenced by the 'ControlToValidate' property of 'FieldRepeater_ctl01_ctl00_validator'.

i have tried changing the literal in the createchildcontrols to a new TextBox(), and then set the id etc then, but i get a similar problem.

can anyone enlighten me?
is this because of the order the controls are rendered in? ie the validation control is written before the editcontrol?
or…

anyhow any help much appreciated

thanks

nat

Best Answer

You have to use editControl.ID not editControl.UniqueID

Also take into account that if editControl must be something that can be used with a required field vaidator. It doesn't make sense this validator for ALL input controls.

Related Solutions

Javascript – Validate decimal numbers in JavaScript – IsNumeric()

@Joel's answer is pretty close, but it will fail in the following cases:

// Whitespace strings:
IsNumeric(' ')    == true;
IsNumeric('\t\t') == true;
IsNumeric('\n\r') == true;

// Number literals:
IsNumeric(-1)  == false;
IsNumeric(0)   == false;
IsNumeric(1.1) == false;
IsNumeric(8e5) == false;

Some time ago I had to implement an IsNumeric function, to find out if a variable contained a numeric value, regardless of its type, it could be a String containing a numeric value (I had to consider also exponential notation, etc.), a Number object, virtually anything could be passed to that function, I couldn't make any type assumptions, taking care of type coercion (eg. +true == 1; but true shouldn't be considered as "numeric").

I think is worth sharing this set of +30 unit tests made to numerous function implementations, and also share the one that passes all my tests:

function isNumeric(n) {
    return !isNaN(parseFloat(n)) && isFinite(n);
}

P.S. isNaN & isFinite have a confusing behavior due to forced conversion to number. In ES6, Number.isNaN & Number.isFinite would fix these issues. Keep that in mind when using them.

Update : Here's how jQuery does it now (2.2-stable):

isNumeric: function(obj) {
    var realStringObj = obj && obj.toString();
    return !jQuery.isArray(obj) && (realStringObj - parseFloat(realStringObj) + 1) >= 0;
}

Update : Angular 4.3:

export function isNumeric(value: any): boolean {
    return !isNaN(value - parseFloat(value));
}

Javascript – How to validate an email address in JavaScript

Using regular expressions is probably the best way. You can see a bunch of tests here (taken from chromium)

function validateEmail(email) {
    const re = /^(([^<>()[\]\\.,;:\s@"]+(\.[^<>()[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
    return re.test(String(email).toLowerCase());
}

Here's the example of regular expresion that accepts unicode:

const re = /^(([^<>()[\]\.,;:\s@\"]+(\.[^<>()[\]\.,;:\s@\"]+)*)|(\".+\"))@(([^<>()[\]\.,;:\s@\"]+\.)+[^<>()[\]\.,;:\s@\"]{2,})$/i;

But keep in mind that one should not rely only upon JavaScript validation. JavaScript can easily be disabled. This should be validated on the server side as well.

Here's an example of the above in action:

function validateEmail(email) {
  const re = /^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
  return re.test(email);
}

function validate() {
  const $result = $("#result");
  const email = $("#email").val();
  $result.text("");

  if (validateEmail(email)) {
    $result.text(email + " is valid :)");
    $result.css("color", "green");
  } else {
    $result.text(email + " is not valid :(");
    $result.css("color", "red");
  }
  return false;
}

$("#email").on("input", validate);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<label for=email>Enter an email address:</label>
<input id="email">
<h2 id="result"></h2>

Best Answer

Related Solutions

Javascript – Validate decimal numbers in JavaScript – IsNumeric()

Javascript – How to validate an email address in JavaScript

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