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How can I keep a value in a text input after a submit occurs?

Answer 1

A:

You could use client side javascript - you save a trip to the server this way.

The downside though : you can really only do basic checking as the user cannot be trusted (for security measures of course ). You can at least "flag" the invalid patterns before making an expensive trip to the server.

jldupont 2010-02-19 12:56:06

I need a PHP only solution right now. :P I'll look into that when I hand in this little homework. Could just describe what I need to do? I don't necessarily want all the code just handed to me.

Serg 2010-02-19 12:57:49

Client side JS would save a trip to the server, but it requires trusting the user. It can only be a "nice for the user" and never a substitute for real checking.

David Dorward 2010-02-19 13:11:54

Answer 2

+1 A:

If a user writes in only his last name, the form should show again with an error message beside the last name field, but the name value should still be there.

Just get their value from $_GET (the form method you are using)

<input type="text" value="" name="lastname" value="<?php echo $_GET['lastname'];?>" />

and so on....

You must also use htmlspecialchars function for security reasons.

More Information Here.

Sarfraz 2010-02-19 12:58:29

**must** not could. Failing to sanitize the data before it goes out of the system will open the site up to XSS attacks.

David Dorward 2010-02-19 13:12:44

@David: you are right :)

Sarfraz 2010-02-19 13:19:04

Answer 3

A:

I think, Javascript is the best answer if you can rely on Javascript. But client side script can be over-ridden. So validate your input on the server later.

Kangkan 2010-02-19 13:00:29

Answer 4

A:

just a small note i had to learn the hard way: displaying an error message and urging the user pressing the back-button (or doing the same using javascript) does not in general preserve values in the input fields.

This seems to be completely browser-specific, e.g. for me it worked on Safari, but not on Firefox...

chros 2010-02-19 13:01:59

Answer 5

+7 A:

Place the variable you need into the "value" field of your input-tag like this:

<input type="text" value="<?php echo htmlspecialchars($_GET['lastname']); ?>" name="lastname" />

AND it's important to quote at a minimum the HTML characters someone might put in (by htmlspecialchars).

initall 2010-02-19 13:02:20

To handle undefined index notice when $_GET isn't set, I usually do this somewhere at the top of scripts $lastname = isset($_GET['lastname'])?$_GET['lastname']:'';

vsr 2010-02-19 13:31:48

Answer 6

A:

Hi,

Its good to do validations on the server side. Your approach seems to be right. You can just maintain a flag which will tell you at the end of the page weather or not the validation was successful.

Example

$flag=ture;

<?php if((isset($_GET['lastname'])) && ($_GET['lastname'] == "")){
       echo "Please write a correct last name.";
       $flag="false";
}
?>

then at the bottom of the page if($flag==true) echo "form submit";

About persistence of value one of the person has correctly mention adding value to your input tag

value="<?php echo $_GET['lastname'];?>"

Hope this helps.

2010-02-19 13:06:45

Answer 7

A:

If you are doing something like

<input type="text" value="" name="lastname" value="<?php echo $_GET['lastname'];?>" />

never never ever forget to check/escape the value you display using e.g. htmlentities(). Otherwise you are open to completely trivial javascript injection attacks!

chros 2010-02-19 13:07:38

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How can I keep a value in a text input after a submit occurs?

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