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Hi
Ive been having a very tedious problem lately where Im not able to display the topics in a forum category. I have been able to display all categories in a forum-style table but when I click on one of the categories I am getting the following error but I dont understand where in my code it is going wrong:

Notice: Undefined index: topic_cat in .../category.php on line 44

I want to get the topics that are linked with a specific category (topic_cat links to cat_id). So for cat_id=2, I want all topics that are assigned topic_cat=2.

Below is my code, can anyone see any problems? Note: this is the code that is currently being processed:

else
        {
            if(mysql_num_rows($topicResult) == 0)
            {
                echo 'There are no topics in this category yet.';
            }


And this is my code:

  else
    {
        //display category data
        while($row = mysql_fetch_assoc($result))
        {
            echo '<h2>Topics in ′' . $row['cat_name'] . '′ category</h2>';
        }
     
        //do a query for the topics
        $topicSql = "SELECT 
                    topic_id,
                    topic_subject,
                    topic_date,
                    topic_cat
                FROM
                    topics
                WHERE
 44-->      topic_cat = '" . mysql_real_escape_string($_GET['topic_cat']) . "'";
         
        $topicResult = mysql_query($topicSql);
         
        if(!$topicResult)
        {
            echo 'The topics could not be displayed, please try again later.';
        }
        else
        {
            if(mysql_num_rows($topicResult) == 0)
            {
                echo 'There are no topics in this category yet.';
            }
            else
            {
                //prepare the table
                echo '<table border="1">
                      <tr>
                        <th>Topic</th>
                        <th>Created at</th>
                      </tr>';
                     
                while($row = mysql_fetch_assoc($topicResult))
                {              
                    echo '<tr>';
                        echo '<td class="leftpart">';
                            echo '<h3><a href="topic.php?topic_id=' . $row['topic_id'] . '">' . $row['topic_subject'] . '</a><h3>';
                        echo '</td>';
                        echo '<td class="rightpart">';
                            echo date('d-m-Y', strtotime($row['topic_date']));
                        echo '</td>';
                    echo '</tr>';
                }
            }
        }
    }
}
Posted

1 solution

this may be probably because the get variable takes the value passed in the url... like products.php?cat_id=2

so you can get cat_id=2 in this example...

may be you are not passing any value so the $_GET in line 44 is not getting any value...

you can check that via a issset function, if isset($_GET['topic_cat']) returns null it is not set and hence you can set it to default value to that you can see the results.
   
Comments
jba1991 5-Jul-14 9:07am
   
Okay cool. So where in the code would I put the isset function? does it replace any existing code?
ShubhamSaxena 6-Jul-14 15:20pm
   
if(isset($_GET['cat_id']))
$cat_id = $_GET['cat_id'];
else
$cat_id = 2 //let 2 be the default category

Now perform the sql query for the category by using the $cat_id to display the topics

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