php - filling in form fields from database values

Instead of thinking about this from a global perspective think about the problem in it's context.

Your starting point (from the server perspective) is that an HTTP GET request has come in from a client for this page, or a client is returning to this page from after a POST request. In either case, the server has located the "resource" (the PHP script) that should handle this request and dispatched it by loading the PHP interpreter with the script file.

The context at this point is at the first line of the script; at the point where the interpreter has just finished parsing and started executing. Ask yourself: does the current request include an active session identifier? If it does have an active session, then check to see if the client has filled in this form before and if they have, substitute the default form values they've previously submitted for the normal form default values. If the client does not have an active session or has not used the form before then show a blank form with default values as needed.

Tip: Consider using this technique to debug your code. Pick a line in your code and place a mental "break point" at that place. Ask yourself: what is the context of this script at this point? What variables are defined? What is the server state? What is the client expecting? Once you have an answer to those questions, writing the code is simple.

From what I see in your code you have the variable in single quotes:

$city = "usercity"; echo $formValue->location('$city');

remove the single quotes, as it will pass '$city' as is, not the value of $city. Try

$city = "usercity"; echo $formValue->location($city);

to make it clearer:

$city = "usercity";
print ('$city'); // will print $city
print ($city); // will print usercity

My last few projects had forms all over the place and telling php to fill out the forms each time was a pain in the arse.

For my current project, I kept the input names the same as the mysql field names. Makes submitting and populating way easier.

When it comes to populating the forms, I use some ajax (jQuery used all over the project so using jquery's ajax() function;

FORM

<form>
<input name="field_one" type = "text" >
<input name="field_two" type = "text" >
<input type="button" value="Send">
</form>

I put a conditional statement at the top of the doc along the lines of:

<?php if($_POST['update']){ 
    $query=mysql_query("SELECT * FROM table WHERE unique_id='$id' LIMIT 1");
    echo json_encode(mysql_fetch_assoc($query));
    exit;
} ?>

Lets say you have a list of items you want to be able to click on and edit (populate the form with it's corresponding data). I assign it a data- attribute and fill it with it's unique id, normally an AI PRIMARYKEY eg:

while($r=mysql_fetch_assoc($data)){
    echo "<li data-unique_id=\"\">$r[name]<span class="edit">edit</span></li>";
?>

$('.edit').click(function(){
    var toget = $(this).parent().data('unique_id');
    $.ajax({
        url:'here so it sends to itself',
        data:'update='+toget,
        success:function(data){
            for (var key in data) {
        if (data.hasOwnProperty(key)) {
            $('input[name="'+key+'"]').each(function(){
            $(this).val(data[key]);
            });
        }
        }
        }
    });

There's a little more work required for <select>, <textarea>, checkboxes, but same general idea applies, (I threw in a couple of if statements, but it could probably be handled way better)

I could probably explain this better, but I hope you get the idea and i've been of some help.

FYI

my inserts are like...

foreach($_POST as $k=>$v){
    $v=mysql_real_escape_string($v);
    $fields.=" `$k`,";
    $vals.=" '$v',";
}
$fields=substr($fields,0,strlen($fields)-1);//to get rid of the comma :)
$vals=substr($vals,0,strlen($vals)-1);//and again
mysql_query("INSERT INTO ($fields) VALUES ($vals)");