I'm writing an ASP.NET page and trying to get validation working. My problem is that I've got a repeater that contains several custom grid controls, each of which has validators and a validation summary.
At first, I didn't assign any validation groups, but this ended up making validation summaries appear for every grid whenever there was an error in one (because the validation summary's validation group was not set, I suppose, which meant it captured all validation errors).
So I assigned a separate validation group for each grid, unique with respect to a certain property on the control. But I have a button at the bottom of the page (with no validation group) that needs to validate the input. Not having a validation group, it won't automatically validate the grids' validators, so I added a click handler that calls Page_ClientValidate(). No dice--validation appears everywhere.
Okay, so I iterate through the validation groups and call Page_ClientValidate(validationGroup) on each if it has any validators. Works fine when only one grid has validators, but when two or more do, it automatically hides all validation summaries but the last one checked. Is there any way to disable this behavior, or a better way to do this entirely?
If I need to, I guess I can go through and unhide the other validation summaries once I've finished iteratively validating (although that might possibly have other implications), but I'd also need to unhide the validator displays (I'm using an image to denote invalid fields). It seems like such an annoying and possibly fragile solution.
EDIT: Oh, a twist. I tried doing the approach I mentioned at the end--re-showing the hidden validators/validation summaries that are invalid--but the Microsoft code prevents that, too; in the first line of the ValidatorValidate(validator, validationGroup, event) method (called by Page_ClientValidate(validationGroup) on each validator in the page), validator.isvalid is set to true, and is only set to the return value of the validation function within a conditional that only runs if the validationGroup parameter matches the validator's. The upshot being, the hidden validators all are marked as valid, making it tough to determine after the fact whether a validator is valid because it's actually valid or because Microsoft was stupid in designing the client-side validation code.
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I have a aspx page with multiple groups to be validated. validation on groups happen based on some conditions I have written.
Currently all my validation work fine with client side validation.
But, when I do a postback the validation summary is getting disappeared. In the post back I am enabling some additional controls which are not yet touched by the user( so validation should not happen on this newly visible controls).
so My problems are:
To Retain the Validation summary generated by client side script on post back.
Only Validation messages that are generated on client side should be visible.
Newly added field should not be validated on postback(fields that are untouched).
Please suggest....
In the post back event handler add the invalid validators by calling Page.Validate("Group");
To Retain the Validation summary generated by client side script on post back.
I think you should check ViewState.EnablViewState=true
Newly added field should not be validated on postback(fields that are untouched).
Use ValidationGroup.Apply different ValidationGroup for different input and related button.
Only Validation messages that are generated on client side should be visible.
Not fully understood.May be by solving 1 & 3 this will disappear .
I'm working on a WebForms application that consists of a number of pages and each page contains a form which the user fills out. Each form corresponds to a part of an entity meaning that the data from one page/form populates a part of the entity's fields or its child entities' fields.
As an example: a Person's name and birth data is filled out on first page, health status on second page, family information on third page etc.
The data should of course be valid before continuing to the next page. My customer doesn't want to deal with jQuery or Javascript so this is ruled out. What is "best practice" for implementing validation in this case?
Entity Framework 4 is being used and most of the GUI controls are implemented in HTML and not by WebForms controls.
If you're using custom HTML for your inputs, then you're probably going to have to use some custom code for your validation. In your server-side form handler you can validate the inputs and render the page back to the user if something was invalid. The input checking could be as simple as:
if (string.IsNullOrWhiteSpace(FormCollection["someRequiredInput"])
You can iterate through all of your inputs, check them according to business logic, and perhaps build a list of errors. Then after the input checking, if the list of errors isn't empty, render the page back to the user with the errors added to a placeholder of some kind. If the list is empty, continue processing the form post.
Even if JavaScript wasn't ruled out, you'd still want to perform server-side validation. Never assume that the client-side code worked as intended or was even executed at all. Client-side validation isn't a security measure, it's just a better user experience. Server-side validation is the only real validation.
(So you may still be able to add client-side validation for that added UX touch, and if the client does indeed disallow JavaScript then they wouldn't see that and would just use the server-side validation instead. This is sometimes referred to as "graceful degradation" where you design a web application to still fully function, albeit with slightly less UX goodness, when the user disables client-side technologies.)
My customer don't want to deal with jQuery och[sic] Javascript so this is ruled out.
Good. Javascript is the wrong place to enforce validation. Any validation you do with javascript is merely a performance optimization. The only acceptable place to truly validate data is on the server.
That out of the way, .Net includes some handy Validation controls you can use. One of those controls is a CustomValidator, that is very easy to override and provide your own server-side code to enforce whatever rules you want. If you're using webforms, these controls are an obvious choice.
Since you have a multi-paged approach, you may also want to look into the Wizard control.
I have a custom class (ServerSideValidator.vb) that validates user input on server side (it doesn't use any of the .NET built in validators, therefore Page.Validate() is not an option for me). I am calling the Validate() method on page.IsPostback event and the class performs without any problem
My issue is, when validation fails (returns false), I want to stop the postback event handler from firing, but load the page along with all the controls and user-input values in them. If I do, Response.End(), the page comes up blank. I can programmatically instruct the page to go to the previous page (original form before postback), but it loses all user-inputs.
I thought of creating a global boolean variable in the page code behind file and check the value before performing any postback method, but this approach takes away from my plan to provide all functionalities inside the class itself. The page object is being referenced to ServerSideValidator.
Seems like all the postback related properties/variables I come across inside Page class are 'Readonly' and I can't assign value(s) to control/prevent postback event from firing.
Any idiea on how I can accomplish this? Please let me know if you need further details
It's probably easier to post back to the same page every time and do your validation there, specifically on the page load event. If the validation fails, you're already on the correct page and don't have to go to a previous page. If the validation succeeds, then you can redirect to another page if you wish, in which case you probably don't need any data.
Edit: This isn't exactly what you asked for, but I have a feeling it will do what you want while fitting into the existing ASP.NET validation design. See http://www.dotnetcurry.com/ShowArticle.aspx?ID=197 and https://web.archive.org/web/20211020145934/https://www.4guysfromrolla.com/articles/073102-1.aspx
Basically, you create a custom class just like you have now, but inherit from BaseValidator. To follow your design, you can create an enum called ValidationType which has Alphabetic, Alphanumeric, etc. In your custom class, create a property called ValidationType that uses the ValidationType enum. Of course you have to add all the validation logic. Then in your aspx page, you can add your custom validator to the page and set ValidationType="Alphabetic", etc. with full IntelliSense support.
Since you use BaseValidator, all the regular validation techniques will work including Page.Validate(), Page.IsValid, etc. You can even create client-side validation JavaScript if you wish.
Having said this, someone has probably already done most of this for you.
Can you tell me when will use CustomValidator. For eg I have Textbox that accept comments from the user. Any reason why the CustomValidator would fit in scenario and what other validators cannot do or is difficult to do?
Your question describes the exact reason to use a CustomValidator: you use it when the existing validators won't do what you need done. For instance, there is no validator that will ensure that the value in text box B is between the values in A and C. You'd have to do that in code, in a CustomValidator.
CustomValidator is meant to give you freedom to implement your own validation logic where other validators just don't do what you need to do.
E.G: When you need to do any kind of validation that doesn't actually require a user input control (such as checking if a cookie exists) or if the control you want to validate has to follow input rules that are too involved for the other validators.
It depends what you are trying to validate - you will need to provide more information.
The CustomValidator lets you write any code you want to perform one or more validations on the data entered into the Textbox. The other validators perform a distinct function like comparing values, checking that a value has been entered or checking that a value conforms to a regular expression.
One thing I've used CustomValidators for in the past was generate a list of error messages to go in a ValidationSummary control. In general, use them whenever you would want to do some custom validation that the standard set of ASP.NET validators don't cover.
I'm looking to make validation for a page in which one or more fields have a value in them. I have an advanced search form in asp.net and I'm trying to pop up an error and not post back if all the fields are empty. I've looked into required fields validators but I'm not sure how to make them work together in a AND type fashion instead of the OR fashion that a validation group of required field validators would imply. I hope this makes sense. Thanks for the help.
i had to do something similar years ago and i was using 1.1 then.
what we ended up doing was creating required field validators but disabling them.
then onload we would loop through the validator dictionary, enable them and check if they passed. if any of them passed we broke off the loop and we continued execution, otherwise, if all of them failed then we displayed a warning. Unfortunately, this would require a postback.
If you want to accomplish this on the client-side then you could write a simple javascript function to take care of it before postback.
for every control, place an onBlur event. javascript will check if there is a value in the field and maintain a flag. then before submission you would check the flag and either allow submission or show warning.
You could just write the javascript validation function yourself to handle this case and attach it to your search button.