using eval() or ob_start() for assigning variables?

[tatlar]

Hi there,

I have a proprietary database that I connect to using PHP. When I grab values from the database tables I have to use the following syntax:

<?php 
list( $var1, $var2, $var3 ) = dbgetv( $database, 'var1','var2','var3' ) ; 
?>

Where var1, var2, var3 are field names.

Say I want to grab the following fields:
1. firstname
2. lastname
3. age

I have these in an array thus:

<?php 
$myvars = array( 'firstname', 'lastname', 'age' ) ; 
?>

How can I ensure that I use these values in my dbgetv query. I.e. I want to use the values in $myvars in my query, such that the resulting query will look like this to the PHP Zend engine:

<?php 
list( $firstname, $lastname, $age ) = dbgetv( $database, 'firstname','lastname','age' ) ; 
?>

I looked at the eval() and ob_start() man pages on the PHP site, but it was not clear to me. All help appreciated. Thanks in advance.

PS: Please note that the database is not MySQL, or PostgreSQL. I cannot go into the database structure. Thanks.

PPS: For the list() part I know that I could do the following:

list( $$myvars[0], $$myvars[1], $$myvars[2] ) ; 

and to the Zend engine this would look like:

list( $firstname, $lastname, $age ) ; 

however it is the second part I am having trouble with. Thanks.

[bogu]

tatlar wrote:

however it is the second part I am having trouble with

This part?

dbgetv( $database, $myvars[0], $myvars[1], $myvars[2]) ;

[Weedpacket]

Well, neither eval() nor ob_start() would be hugely useful....

Is your problem that you don't know in advance which fields will be asked for in the dbgetv call? Because if you want the code to look like

list( $firstname, $lastname, $age ) = dbgetv( $database, 'firstname','lastname','age' ) ; 

when it's evaluated, then the obvious code to write would be

list( $firstname, $lastname, $age ) = dbgetv( $database, 'firstname','lastname','age' ) ; 

On the other hand, if the fields requested are decided on at runtime, so that you're writing

dbgetv( $database, $field1, $field2, $field3 ) ;

then you don't want the variables to have the same names as the fields, because you won't know what the variables are named when you want to use them. What you'd really want to do in that case is have dbgetv() return an associative array, using the requested field names as keys.

If you can't change dbgetv then things get messier. I'm going to take a wild guess and assume that dbgetv() can take a variable number of arguments. Let's say you've got a list of the fields you're requesting in an array.

$fields_to_request = array('firstname', 'lastname', 'age');

And I'm going to take a further wild guess and assume that dbgetv() will return fields in the same order that they're asked in - otherwise you're stuffed.

$returned_values = call_user_func_array('dbgetv', $fields_to_request);

And then you just need to pair off the elements of $fields_to_request with the elements of $returned_values, so that you get $result['firstname']="Firstname", $result['lastname']="Lastname", etc. So that the results are finally in the form that dbgetv() should have returned them in in the first place.

The pairing off could be done in PHP5 by writing

$result = array_combine($fields_to_request, $returned_values);

. In earlier versions a loop would have to be written to do the task.