[SOLVED] PHP - Return Array from a Function issues... GRR!

wh33t · 01-09-2012, 06:33 PM

Hey guys, can anyone tell me what is going wrong with this script?

Code:

//This function retrieves all of the parents of a category
function category_family($category_id)
{
  
  global $parent_category_array;
  
  //Select the child category that we want to retrieve the parents for
  $query = 'select * from item_categories where item_category_id = "' . $category_id . '"';
  $result = mysql_query($query);
  $a_parent_category = mysql_fetch_assoc($result);
  
  //If we found a parent category
  if(is_array($a_parent_category))
  {
    
    echo 'Found [' . $a_parent_category['item_category_name'] . ']<br />';
    
    //Record it.
    $parent_category_array[] = $a_parent_category;
    
    //Check again to see if we will find another (recursively call itself again until no more have been found)
    category_family($a_parent_category['item_category_parent']);
    
  } else { //If we didn't managed to find a parent category
    
    //Even though we didn't find a parent category this time, it's possible we found one before
    if(is_array($parent_category_array))
    {
      
      echo 'Exiting with an array';
      
      //If we found at least one category, return the array.
      return $parent_category_array;
      
    } else {
      
      echo 'Exiting with out an Array';
      
      //If we never found one category ever, just return false.
      return false;
      
    }
    
  }
  
}

//Load all of the parents
$parents = category_family(2907);

print_r($parents);

The output of this script is as follows.

Quote:

Found [Sub Sub Category]
Found [Sub Category]
Found [Main Category]
Exiting with an array.

Ok, so what I'm gathering is that the function is indeed locating parent categories. That it is exiting while it knows that it's found parent categories yet for some reason I am unable to retrieve the category array from the function when I try to create an array called "$parents" ($parents = category_family(2907)

What the HELL am I missing here?

Snark1994 · 01-10-2012, 04:04 AM

I dunno if this is the issue, but you're certainly mixing global variables with local ones (local ones being preferred). What happens if you add

Code:

print_r($parent_category_array);

?

I would be more happy if each time you returned from category_family() you returned an array or false (which you do) but then didn't update the $parent_category_array at all.

You would just call

Code:

return array_merge(category_family(blah),$a_parent_category);

when returning (or similar, I'm at school so can't check code

)

Hope this helps,

heinblöd · 01-10-2012, 09:21 AM

just had a quick look , but I would say that your condition

Code:

if(is_array($parent_category_array))

will always be true even when you don't get a result from the SQl
as you declared an empty array before

wh33t · 01-10-2012, 11:07 PM

Hey guys, I appreciate the replies. I have since altered the script to further investigate where I'm going wrong here. Here is the new code.

Code:

//This function retrieves all of the parents of a category
function category_family($category_id)
{
  
  global $parent_category_array;
  
  //Select the child category that we want to retrieve the parents for
  $query = 'select * from item_categories where item_category_id = "' . $category_id . '"';
  $result = mysql_query($query);
  $a_parent_category = mysql_fetch_assoc($result);
  
  //If we found a parent category
  if(is_array($a_parent_category))
  {
    
    echo 'Found [' . $a_parent_category['item_category_name'] . ']<br />';
    
    //Record it.
    $parent_category_array[] = $a_parent_category;
    
    //Check again to see if we will find another (recursively call itself again until no more have been found)
    category_family($a_parent_category['item_category_parent']);
    
  } else { //If we didn't managed to find a parent category
    
    //Even though we didn't find a parent category this time, it's possible we found one before
    if(is_array($parent_category_array))
    {
      
      echo 'This is the Array being echo`d from the function.<br />';
      
      print_r($parent_category_array);
      
      //If we found at least one category, return the array.
      return $parent_category_array;
      
    } else {
      
      echo 'Exiting with out an Array<br />';
      
      //If we never found one category ever, just return false.
      return false;
      
    }
    
  }
  
}

//Load all of the parents
$parents = category_family(2907);

echo '<br />This is the Array being echo`d from outside of the function.<br />';

print_r($parents);

This is it's output now.

Quote:

Found [Sub Sub Category]
Found [Sub Category]
Found [Main Category]
This is the Array being echo`d from the function.
Array ( [0] => Array ( [item_category_id] => 2907 [item_type_id] => 1 [item_category_name] => Sub Sub Category [item_category_desc] => [item_category_parent] => 2906 [item_category_order] => 0 [date_created] => 1326071099 ) [1] => Array ( [item_category_id] => 2906 [item_type_id] => 1 [item_category_name] => Sub Category [item_category_desc] => [item_category_parent] => 2767 [item_category_order] => 0 [date_created] => 1326071092 ) [2] => Array ( [item_category_id] => 2767 [item_type_id] => 1 [item_category_name] => Main Category [item_category_desc] => Here is a description. [item_category_parent] => 0 [item_category_order] => 1 [date_created] => 1312659389 ) )
This is the Array being echo`d from outside of the function.

So from what I gather. EVERYTHING is working as I expect it to. The function is calling itself recursively as it should. When it fails to find any more Parent Categories it is exiting the function EXACTLY where I expect it too. "This is the Array being echo`d from the function." is running from:

Code:

echo 'This is the Array being echo`d from the function.<br />';
      
print_r($parent_category_array);
      
//If we found at least one category, return the array.
return $parent_category_array;

I also notice it is indeed printing out the $parent_category_array right in the exit statement. The problem appears to be with returning it! GRR! What is going on! Is that not how you return an array from a function? Shouldn't this work:

Code:

function make_an_array()
{
  $array_name[0] = 'some value';
  $array_name[1] = 'some other value';

  return $array_name;
}

$new_array_from_a_function = make_an_array();

Nominal Animal · 01-11-2012, 12:24 AM

Quote:

Originally Posted by wh33t

Code:

category_family($a_parent_category['item_category_parent']);

When you do the above recursive call, you discard the return value!

So, if you have nested results (and you do), the very first recursive call will just drop the results on the floor and return nothing. Note that after that call no return statement will be executed.

Consider this recursive example.

Code:

function babushka($depth, $array = FALSE)
{
    if ($depth > 1)
        $array = babushka($depth - 1, $array);

    if ($array === FALSE || $array === NULL)
        $array = array();
    else
    if (!is_array($array))
        $array = array( $array );

    return array( 'depth' => $depth, 'array' => $array );
}

var_dump(babushka(1));
var_dump(babushka(5, array("One", "Two"));
var_dump(babushka(4, babushka(3, babushka(2, array("1", "0")))));

Your make_an_array() example function does work, if you first initialize $array_name to an empty array, i.e.

Code:

function make_an_array()
{
  $array_name = array();
  $array_name[0] = 'some value';
  $array_name[1] = 'some other value';
  return $array_name;
}

although a much simpler way to write the same function would be

Code:

function make_an_array()
{
  return array( 0 => 'some value',
                1 => 'some other value' );
}

Hope this helps.

wh33t · 01-11-2012, 01:42 AM

I get it now. Thanks for your help man.

The problem is that I was assuming that when I recursive called the function that it wouldn't run any more statements after.

This now works as expected.

PHP Code:


			
//This function retrieves all of the parents of a category

        function category_family($category_id)

        {

          

          global $parent_category_array, $run_times;

          

          //Select the child category that we want to retrieve the parents for

          $query = 'select * from item_categories where item_category_id = "' . $category_id . '"';

          $result = mysql_query($query);

          $a_parent_category = mysql_fetch_assoc($result);

          

          $run_times++;

          

          //If we found a parent category

          if(is_array($a_parent_category))

          {

            

            //Record it.

            $parent_category_array[] = $a_parent_category;

            

            //Check again to see if we will find another (recursively call itself again until no more have been found)

            category_family($a_parent_category['item_category_parent']);

            

            return $parent_category_array;

                        

          } else { //If we didn't managed to find a parent category

            

            //If we didn't find a parent.

            return false;

            

          }

          

        }

        

        //Load all of the parents

        $parents = category_family(2907);



        print_r($parents);

Snark1994 · 01-11-2012, 10:48 AM

Well done, if you don't have any further questions can you mark this thread as SOLVED please? (and mark e.g. Nominal Animal's post as being 'helpful', as I'm guessing it probably was

)

Thanks,

wh33t · 01-11-2012, 04:52 PM

Will do. Thank you LQ!