[RESOLVED] Using a variable in a $row-> call from sql is breaking the code

MikeCxt

I've never had to use a variable in this position, but I am obviously misunderstanding something, as this is the code...

$row = mysql_fetch_object( mysql_query("SELECT * FROM book_bundle WHERE bundle_id='$bundleID'") );

This selects a single row from my database.

if ( !empty($row) ) {

  if 		(!empty($row->book_name_4)) {$field_count=4;}
  elseif 	(!empty($row->book_name_3)) {$field_count=3;}
  elseif 	(!empty($row->book_name_2)) {$field_count=2;}
  elseif 	(!empty($row->book_name_1)) {$field_count=1;}
  else {}

  for ($i=1; $i<=$field_count; $i++){
  	echo"
		<img src='/images/thumbs/$row->book_image_$i.png' />
		$row->book_name_$i
		<br />
  ";
  } 

}

The issue is in the FOR statement. Before this was a FOR statement, I just repeated the same code 4 times, and inside the difference was that instead of $row->book_image$i and $row->book_name$i, the $i's were '1' in the first block of code, '2' the second time, and so on. It was manually coded in.

I tried to shrink the code using the FOR statement, but I can't seem to pass a variable inside the $row-> call, without breaking it. This code never looks up the $row, it outputs just '1' the first time, '2' the second time. It disregards the $row-> and disregards all text before the $i as well. I don't understand this behavior.

On the other hand, if I change $i to '1', then it works as expected, giving me the book name and picture from the database, only it repeats the same one 4 times as expected from the FOR statement. I just can't figure out how to turn that number into a variable and have the statement work.

Also, while testing, I changed "$row->book_name_$i" to "$row->$i". This broke all code from this point forward when displayed.

I'm sure there's a simple reason why variables don't work like this, or how to properly do it, but I don't know the terminology for these. I've been searching google and php.net/manual, but without knowing what to call them, I've had no luck discovering the answer. Thank you for any help.

mrbaseball34

use mysql_fetch_array() and try:

$row['book_name_'.$i]

MikeCxt

I changed the sql code to mysql_fetch_array() instead of mysql_fetch_object().

I then used

$row['book_name_'.$i]

No change, it still does not work. In fact, the following won't work either (with no variable inside):

$row['book_name_1']

mrbaseball34

That's strange. Have you looked at the "Variable variables" topic in the help?
It has an example there on class properties that may interest you as it can be used with objects as well.

MikeCxt

I searched about Variable Variables, but so far that hasn't yielded the answer.

Let me simply it, as even simplified it isn't working. This does not work:

$book='book_name_1';
  	echo"
		$row->$book
  ";

This does work:

echo"
		$row->book_name_1
  ";

bradgrafelman

You have to use the "complex syntax" for that, e.g.
[Php]"{$foo->{'some_text_' . $bar}}"[/code]

See the manual page for a [man]string[/man] for more information.

bradgrafelman

You have to use the "complex syntax" for that, e.g.
[Php]"{$foo->{'some_text_' . $bar}}"[/code]

See the manual page for a [man]string[/man] for more information.

mrbaseball34

Yes, he forgot the curly braces, like in the Variable variables topic says.

MikeCxt

Thank you bradgrafelman and mrbaseball34. It work's perfectly now. I never knew about complex syntax, but after reading the strings part of the php manual, it makes sense now. I never actually found the 'variable variables' topic, I looked in the different help sections, ran a search on that term here, ended up reading about it on other sites, but the other sites never explained the curly braces.

Thanks again.

mrbaseball34

MikeCxt;10960810 wrote:
I never actually found the 'variable variables' topic, I looked in the different help sections, ran a search on that term here, ended up reading about it on other sites, but the other sites never explained the curly braces.

Well, I used a CHM of the manual so I don't know if it is in the online manual or not.

Ooh, I found it:
http://us3.php.net/manual/en/language.variables.variable.php