query into multidimensional array

[turpentyne]

I'm trying to find a good simple tutorial on how to take my query and turn it into a multidimensional array, but can't seem to find anything.

 

basically I have this:

 

?php 
include("../builder-test-code/dbc.php");


$query_options  = "SELECT component_name, image_filepath, component_category FROM tbl_components";
$result = mysql_query($query_options);

while($row = mysql_fetch_assoc($result)){

$categorized_items = array();
// something remotely like this?
$categorized_items[$row['component_category']] = array($row['component_name'], $row['image_filepath']);


}

?>

 

basically I am pulling all the results from a table with these three rows, and I'm trying to group them into individual arrays by the column "component_category" so I can figure out how to print the results of each array out to the page.

[xyph]

Why not just ORDER BY component_category in your query?

 

To answer your question, you may want this

 

$categorized_items[$row['component_category']][] = array($row['component_name'], $row['image_filepath']);

 

The extra [] on the end will 'push' the data in to a new key of the array.

[Barand]

put

 

$categorized_items = array();

 

before the start of the while loop otherwise you will clear the array on each iteration

[Christian F.]

Nope, it won't.

for ($run = 0; $run < 10; $run++) {
    $arr['test'][] = array ($run);
}
var_dump ($arr);
/* Result:
array(1) {
  ["test"]=>
  array(10) {
    [0]=>
    array(1) {
      [0]=>
      int(0)
    }
    [1]=>
    array(1) {
      [0]=>
      int(1)
    }
    [2]=>
    array(1) {
      [0]=>
      int(2)
    }
    [3]=>
    array(1) {
      [0]=>
      int(3)
    }
    [4]=>
    array(1) {
      [0]=>
      int(4)
    }
    [5]=>
    array(1) {
      [0]=>
      int(5)
    }
    [6]=>
    array(1) {
      [0]=>
      int(6)
    }
    [7]=>
    array(1) {
      [0]=>
      int(7)
    }
    [8]=>
    array(1) {
      [0]=>
      int(
    }
    [9]=>
    array(1) {
      [0]=>
      int(9)
    }
  }
}
*/

That said, it is a very good practise to do so anyway. Cuts down on the number of warnings, and avoids potential problems.

[Psycho]

$query  = "SELECT component_name, image_filepath, component_category
           FROM tbl_components";
$result = mysql_query($query);

$categorized_items = array();
while($row = mysql_fetch_assoc($result))
{
    $category = array_pop($row);
    $categorized_items[$category][] = $row;
}

[Pikachu2000]

Either way, initializing an array or variable by assigning it a value doesn't generate any notices anyhow.

[Barand]

Nope, it won't.

 

 

Yes it will.

.

$categorized_items = array();

 

will create a new empty array on each loop.

[Pikachu2000]

Yes, Barand is right. Having $categorized_items = array(); inside the while() loop, as it is now, will initialize a new array on each iteration of the loop.

[Christian F.]

Oh, snap! Didn't see that he'd put it inside the loop. 

Better go get me some brain fuel, I think. Sorry about the mixup.

[turpentyne]

haha! Now my head is spinning from the replies!

 

I've gotten to here, but now I'm not sure how/where I echo a header for each nested array, when I'm printing to the page?

 

$categorized_items = array();

$query_options  = "SELECT component_name, image_filepath, component_category FROM tbl_components";
$result = mysql_query($query_options);

while($row = mysql_fetch_assoc($result)){
$categorized_items[$row['component_category']][] = array($row['component_name'], $row['image_filepath']);
}

function PrintArray($categorized_items)
{

if(is_array($categorized_items))
{

	foreach($categorized_items as $key=>$value)
	{

		if(is_array($value))
		{

		PrintArray($value);

		}
		else
		{

		echo " $key: $value<br>";
		}
	}
}
}  

?>

<!--html -->
<?php
echo "and now...<br>";
PrintArray($categorized_items);

?>

[Barand]

print_r($categorized_items) does a pretty good job of recursively printing array contents.

[Psycho]

Why dump the results into an array only to use the array for output. Just create the output from the query results.

 

$query  = "SELECT component_name, image_filepath, component_category
           FROM tbl_components
           ORDER BY component_category";
$result = mysql_query($query);

$category = false;
while($row = mysql_fetch_assoc($result))
{
    if($category != $row['component_category'])
    {
        $category = $row['component_category'];
        echo "<br>{$category}<br>\n";
    }
    echo "{$row['component_name']} <img src='{$row['image_filepath']}'><br>\n";
}

[turpentyne]

I was told by someone that they felt the best way to generate a list with headers was to put them in a multidimensional array and then loop through it to create something like this. They mentioned the other way that Xyph suggested at the start of this thread (and that you just suggested), but said the array method was better in their mind.

 

CATEGORY 1

item 1

item 2

item 3

 

CATEGORY 2

item 4

item 5

item 6

 

and so on... Is this not a good way to do this? maybe I'm taking the long way around? Or are there benefits you can think of?

 

right now, it's printing everything to the page, but not breaking it apart.

 

[Christian F.]

If you know the structure of the array, and that it always the same number of elements in the second dimension, then you're far better off skipping that second loop.

 

Also, unless you need to use the data in another location, you don't need to save it in an interim array either. It's just a waste of time and memory.

 

I'd do something like what Psycho posted above, if I were you. Only saving the completed table to a variable, instead of printing it outright.

[turpentyne]

Well, that was certainly easier...

 

quick follow-up question and I'll call this thread solved.

 

what about a footer? I've got a header , but I also need a footer, and didn't think about that...

 

Is there some similar method to the header snippet that can be used to detect when to put a bit of code before going on to the next grouping?

 

 

[Christian F.]

If you're thinking about a footer for each section, then just print it out before the header for the next. Just remember to save the previous line at the bottom of the loop first, so you can get the necessary data.

Doing it that way means you don't have to detect twice, but can just refer to the previous line's data before starting on a new category.

 

Something like this, in other words:

while ($row = fetch_array ()) {
    if (if($category != $row['component_category'])
    {
        // Add a footer unless this is the first row, and thus the first category.
        if (isset ($prev)) {
            $output .= $prev['footer']."</p>";
        }
        $category = $row['component_category'];
        $output .= "<p>{$category}<br>\n";
    }
    $output .= "{$row['component_name']} <img src='{$row['image_filepath']}'><br>\n";
    $prev = $row;
}

Simple and easy.