Forum Level Tree Forum 1 > Forum 2 > Forum 3 etc...

jonno946

I am making a forum system for my site, however i am having problems with the level tree (i.e Level1 > Level2 > Level3 etc... ).

Basically by database layout looks like the following:

id Name parent

1 | Hardware | 0 |
2 | Web Design | 0 |
3 | Hard Drives | 1 |

4 | PHP & MySQL | 2 |

Now, say if i am currently in the 'PHP & MySQL' forum, the tree would be: 'Web Design > PHP & MySQL'.

The problem is, how do i make the 'Web Design > PHP & MySQL', from just knowing the id?

For example:

htttp://www.mysite.com/view_forum?id=4.

I know there is some loop involved, and possibly inputting the data into an array, thus:

array[1] > [array[2] > array[3] etc...

Any help would be massively appreciated, as ive been twiddling my thumbs over this one for quite some time!!

Thanks,

Jonathan

Stu

I would imagine it depends on how you've got your database set up but this is how I did it on my forum.

For the table containing the boards, they all had an ID (as you should with virtually everything, so I'm told 🙂). In the table that contained the threads, they had a column for "board" which was set when someone posted. It was basically the ID of the board in which the thread was posted.

It was then a case of querying the database get teh ID the thread was posted in. Then using the result returned from that you query the boards table to get the name of the board.

Hope that was understandable!

jonno946

i understand that, but more than likely youf forum only had one level. i.e:

Forums > hardware

Mine has for example:

Forums > Hardware > Processors > AMD > Athlon

Now if i did what you just said, i would get:

Forums > Athlon

See what i'm saying?

Stu

You would need to do a few extra steps then such as querying a categories table for the name. The logic would still be the same.

jonno946

it seems i would have to query the current forum, for its parent id, the query that id for that forums parent id, and then query that parent id for that forums id... etc... , until the parent id = 0.

That seems the only logical way to do it😕

jonno946

anybody 😕

yelvington

Recursion.

yelvington

OK, I'll be a little more verbose.

What you need to do is get a record, build the link string, and if the record has a parent, recurse.

Since you're building the string from right to left you can't just print it. Instead, concatenate.

You can't write a recursive SQL statement with MySQL. You'll have to do it with PHP.


// Build a breadcrumb trail from 0 to this location $id
function breadcrumbs($id)
        {
        $result = mysql_query("select * from mytable where
id='$id'");
        $item = mysql_fetch_object($result);
        $trail =
"<a href=\"view_forum.php?id=$item->id\">$room->title</a> > $trail";

    if ($room->roomparent)
            $trail =                      breadcrumbs($room->roomparent) . $trail;
    return $trail;
    }

Then invoke the function as follows

echo breadcrumbs($id);

Yes, you could write a while() loop that would do this. Recursion is actually simpler.

jonno946

its amazing theres something for everything with php 😃

Thanks for the help by the way, much appreciated!

sadly, i just tried that and it just prints:

and nothing else 😕

Ive checked the sql query, that seems to be fine, and im definately calling up the page ok view_forums.php?id=41 for example.

Any ideas?

BuzzLY

$_GET['id']

BuzzLY

If you want to do breadcrumbs properly, I strongly, STRONGLY recommend you read this article. Do it right, and you'll have a very robust breadcrumb app in PHP. Do it wrong, and you'll tie up your MySQL resources in a knot.

jonno946

thanks for all the input!

I checked out the tutorial, and all looks a bit too complicated for me :o

i still cannot get that method yelvington mentioned to work, ive changed to the $_get method buzz mentioned, however that brings up a parse error 😕

Thanks for all of the input guys!!

BuzzLY

Please show us the code where you are using the $_GET... it should be working unless you typed something wrong in the code.

jonno946


function breadcrumbs($id) { 
        $result = mysql_query("select * from `forums` where 'parent' = '$id'"); 
        $item = mysql_fetch_object($result); 
        $trail = "<a href=\"view_forum.php?id=$item->id\">$room->title</a> > $trail";
        if ($room->roomparent) 
                $trail =                      breadcrumbs($room->roomparent) . $trail; 
        return $trail; 
}

echo breadcrumbs($_GET['id']);

However... i have tried different combinations with no luck 🙁

laserlight

Where is $room defined?

It is an undefined local object.

yelvington

Sorry, c/$room/$item

That code was stripped down from something I wrote three or four years ago.

jonno946

Any chance you can re-post the whole working code as im not sure where you meant the c/$room/$item
to go.

Your help has been much appreciated!!

Jonathan 🙂

yelvington

Wherever you see $room, change it to $item.

The original code is here:

http://prattle.sourceforge.net/

jonno946

you guys make it look so easy!!

Sorry to be dumb, but it still wont work, and all i get printed to my screen is '>', and when i view the source its:

What am i doing wrong?!

Here is my current source:

<?php

// Log into MySQL database
$db = mysql_connect("localhost", "db_username", "db_password") or die ("Could not connect"); 
mysql_select_db("db_name") or die ("Could not select db"); 

function breadcrumbs($id) { 
        $result = mysql_query("select * from `forums` where 'parent' = '$id'"); 
        $item = mysql_fetch_object($result); 
        $trail = "<a href=\"view_forum.php?id=$item->id\">$item->title</a> > $trail";
        if ($item->parent) 
                $trail = breadcrumbs($item->parent) . $trail; 
        return $trail; 
}

echo breadcrumbs($id);

?>

I have checked your source code yelvington, but the code you guys are using is of a much higher standard than i am used to!!

What does -> mean for a start!!

Again, sorry to be dumb, but do you know what could be wrong?

Thanks.,

Jonathan

BuzzLY

If you are familiar with Object Oriented Programming, $item->parent is equivalent to $item.parent. In other words, the "parent" column in the $item that was pulled from the database.

I'd like you to modify your code a bit. Change your last line to this:

//echo breadcrumbs($id);
echo "ID: " . $id . "<br>";
echo "ID: " . $_GET['id'];

Load the page. If there is an id# on both lines, then you have register_globals = "On," and your code should work.

If there is only an id# on the second line, then register_globals = "Off." In this case, add the line "$id = $_GET['id'];" just before "echo breadcrumbs($id);"

If there is not an id# on either line, then either you didn't include "?id=x" in your URL, or you are using an older version of PHP (prior to 4.1.0) that doesn't recognize $_GET. Use $HTTP_GET_VARS['id'] instead.