I need to validate a form in php and display some error messages in the view if there are validation errors. The problem is that once the form is submitted, sending the user back to the page will clear all the of the completed form fields. Is there a simple way to not lose the unvalidated form data?
The only solution I can come up with is reverse engineering the $_POST variable, but I'd like a more elegant way to do it.
Don't send the user anywhere, but re-render the form right where you are, pre-populating the form with the entered values. That would be the most common method.
The second way would be storing the values in session variables, but that should be the last resort if the project structure doesn't allow for the first approach.
Validate on the client side.
If you must validate on the server side, made an ajax call (so you won't have to refresh the page) to the server with the elements you want to validate. Make the validations you need and return an answer back to the page (is valid or not).
If answer is valid, you can proceed (Note: you may not need to return to the page after the validation, if all the elements you need to proceed are also the ones validated).
If it's not valid, the answer should return the invalid elements (and possibly a error message for each) so that you can display the error messages you want.
If in php code that you use to prepare the form you always set field values to whatever exists in $_POST array, then in validation code you can simply conditionally include that form file and it will render itself with user values. When you render the form the first time (empty form) $_POST will not have elements with field names, and the form will be empty.
Related
I have a form that the user will submit multiple values to PHP via POST.
The PHP takes the input and if the data entered is valid, it will display a second form for the user to fill out.
After the user has filled out the second form, I need to process the data that was entered in the first form again as well as the data entered in the second form.
What is the best way to access the form data from the first PHP form?
Should I put each value into its own SESSION variable and access it when I need it again later?
I just wasn't sure if this is the best/cleanest way to accomplish this task.
Thanks!
I like the idea of sticking it in the $_SESSION, but depending on your validation needs, it might be better for you to simply use client-side (javascript) validation and some conditional logic to reveal additional form fields. Then you only have one efficient post to the server with all necessary information.
I think it should go without saying, but nevertheless, once it does post to the server you want to re-validate and sanitize the data.
In a form(in Drupal) I want to have a temporary field that there is no need to save it's value in database. So I need a way to prevent form from sending the field's value to $_POST array. Is it possible?
If it's outside the form being submitted, it won't be sent by the browser.
If it doesn't have a name, it won't be sent by the browser.
If it is disabled, it won't be sent by the browser.
See Form submission: Successful controls for the complete rules.
That said, your approach is very very wrong. You shouldn't decide what to put in a database based on what comes from the client. The client can send you anything!
Just don't give it the name="" attribute.
You can also exclude it from the $_POST array when placing it in the database
Hi I'm a relative newbie.
Have a mail contact form set up with a captcha image generator.
When the captcha is verified, on submitting the form, a php page is actioned which further validates the input data (checking against spam).
Challenge: would like to retain form data in case of error in enterred capthca code and needing to return to form.
If I use a sticky form with the form sticks okay but I cannot see how I then direct http to the php script for form data validation.
So I figure the answer is a javascript function to validate the captcha and stay within the same page where the form appears, ideally just having a pop up message (alert ...) if the enterred code is wrong, before sending the http to the php script page.
I have seen that this can be done but I cannot adapt the code to the captcha I use (i.e. webspamprotect.com) Could any body suggest a generic js function useable with any captcha ?
Would be most grateful for any input.
MANY THANKS
Steve
It doesn't make sense to be able to validate the CAPTCHA with javascript on the client. If you made it possible to validate with Javascript a scammer could use the validation function to test their guesses before they sent them to the server, so they would always be able to get the answer right.
You could implement an AJAX call requesting the server to validate the attempt instead of requiring a full page refresh, but the validation must still be done on the server.
When the captcha is generated the written word is usually stored inside the session or written into a hidden input field, so it can be validated against the user supplied word, when the form is submitted back to the PHP script.
You could pass the session variable holding this to your JavaScript (or read it from the hidden input if present) when rendering the page holding the form and captcha. Then, when the user clicks submit, intercept the call and check if the entered word matches the expected word.
As for retaining the values: just add the values to your HTML form value attribute. Make sure you escape the output in case users supply malicious code.
EDIT: agreeing with everyone who says you still have to validate the input on the server side as well. Client Side validation can easily be tinkered with and is nothing but a convenience feature for users, so they can fix their input before submitting.
simply check the value of "g-recaptcha-response"
if($('#g-recaptcha-response').val()==''){
alert('captcha not ticked');
}else{
alert('captcha ticked');
}
I want to ask a best practice question.
Suppose I have a form in php with 3 fields say name, email and comment.
I submit the form via POST. In PHP I try and insert the date into the database.
Suppose the insertion fails.
I should now show the user an error and display the form filled in with the data he previously inserted so he can correct his error. Showing the form in it's initial state won't do.
So I display the form and the 3 fields are now filled in from PHP with echo or such. Now if I click refresh I get a message saying "Are you sure you want to resend information?".
OK.
Suppose after I insert the data I don't carry on but I redirect to the same page but with the necessary parameters in the query string. This makes the message go away but I have to carry 3 parameters in the query string.
So my question is:
How is it better to do this? I want to not carry around lots of parameters in the query string but also not get that error. How can this be done? Should I use cookies to store the form information.
Your first scenario seems the most valid.
i.e.
User submits the form
Some problem prevents submission, so form is re-displayed
If user "refreshes" they see the usual message about re-sending information (although their most likely path of progression is to re-submit the form that you are kindly re-populating for them).
The "Are you sure you want to resend information?" message is perfectly valid in the event of someone refreshing the page after a form submission, so don't write code to specifically break this behaviour.
I think generally people would temporarily store the submitted data in a session variable, and send the data back to the client.
Maybe it is besides the point but you mentioned "wrong dates", and I think many would say you should arrange things so that the user cannot unintentionally send you wrong dates.
Im trying my first form validation with PHP.
I need some guidance with the logic.
I have purchase.php (which has the form) and review-purchase.php(which sets SESSION variables and displays the user data inputted)
If any of the fields fail validation I don't want the user to get to review-purchase.php
Should I be sending the user to the review-purchase.php script, checking validation there and then redirecting back the purchase.php with an error message?
or
should I be using an if/else statement with $_SERVER['php_self'] etc in the form action="" and keep all the validation on the purchase.php page itself and only letting purchase-review run if everything passes validation?
Sorry for the confusing question but i myself am very confused...
That's a question many people ask themselves, and there is probably not one right answer...
What I generally do, in your case, is :
purchase.php displays the form
that form posts on itself (ie, purchase.php)
when data has been submitted, it is dealt with -- still in purchase.php
if there is an error (like something not OK in the input), you can re-display the form really easily, this way : you already have every values that were typed in by the user
if there is no error, you can do whatever you have to with the data ; like set it in session, if that's what you need, or save it to database, for instance.
only when everything was OK (data validation OK and storage OK), you redirect to "confirm.php"
that confirmation page does nothing except display a message saying "thanks for your purchase", or something like that.
It means putting more stuff in your purchase.php, yes :
(re-)displaying of the form
dealing with the input
But, this way, it is really easier to re-display the form, pre-filled with what the use first typed, when there's a validation error.
You can use functions/classes/methods or even some included files, though, to not end up with one big chunk of un-readable / un-maintenable code...
If your form posts to another page, it'll be really harder to re-display the form... If you are using redirections, you'll to pass everything in the URL, and it'll be a mess (And there's a size limit, too)
Here, it means I would totaly remove your review-purchase.php file ; and transform it to a confirmation page, so the user knows everything was OK and his purchase is being take care of.
I suppose it's quite what you meant in your last paragraph, actually :-)
Just beware : you have to think about escaping data before injecting it back into the form (see htmlspecialchars and/or htmlentities) ; that is true for everything you get from the user (And, probably, for PHP_SELF too, I'd say) ;-)
Well, it seems you have a misconception about where and when PHP code is executed. If you want to validate user input on the server side - with PHP (and you should because any JavaScript validation on the client can be worked around by a nefarious user) - the PHP validation can only occur after the user has posted data. That is no matter to which page the user posts the data - be it the original form or a different page.
So, in your situation if you want users to go to a page if validation is successful and to a different page is validation fails yo will need to do a redirect anyway.
In this case you have two paths:
user requests Purchase.php and fills out the form
user posts data to validation page
if data is valid -> display purchase review information
else -> re-display form page and have user re-enter data
So if Purchase.php posts to itself, you can validate there and redirect to review.php only if data is valid. Which means that in the successful case you do 2 redirects and in the failed case you do only 1 post.
On the other hand, if you post directly to review.php and you validate there, you have 1 post in the successful case, and 2 in the failed case.
The above is true no matter how you spin it - unless you use the same URL for the form and the review, in which case you can put logic in the same place to do the form, validation and purchase review in the successful case.
I hope this helps.
The most common way of doing this would be to do all your validation checks in purchase.php. This way, if there are validation errors, it's easier to re-display the form with all of the information that the user has already entered.
If the validation passes, you can do a redirect to review-purchase.php with the necessary purchase information set in a database, or possibly $_SESSION if you're not using a database.
If you can separate the validation code into functions, and the display code into templates to be included, you can achieve a nice separation of logic that would allow you to use them from whichever file you go with. You might be able to avoid a redirect in that way, ie. in purchase.php you could check if there's $_POST input, validate it, and either re-display the form template, or display the purchase review template.