show posts belong to any category in php

hi mate,

i am just start coding with my PHP, i have to know about populate (fetch) content from database anyway so you no need to worry about this section :)

today when i am trying to implement my new web task that my use can select any post category and i have to done with this task but there is one thing getting wrong :(

first of all, here is sample of my URL to get list of post based on category that my user clicked:

Quote:

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http://localhost/cat.php?id=1

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so this URL would fetch all content (post title, post author, post content, cat label, etc) but when i enter non exist cat id it will show show error like invalid argument supplied for foreach.

what should i do when my user want to get non exists cat_id without any php error instead show a 404 page error :x

You should work out first what you want to do if a cat has not been chosen:

Show all posts?
Show nothing, just a warning?

Likewise, if the cat id returns no records (presumably this should not happen, but could).

Show all posts?
Show nothing, just a warning?

A conditional check can be done like this.

PHP Code:

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// use (int) to typecast the incoming cat variable to an integer
// if it is not able to cast it as an integer, it will return 0
// so only go on with the action 
// IF id is set AND id is recognised as an integer greater than 0

if( isset($_GET['id'] && (int)$_GET['id'] > 0){

// now an integer has been submitted, but you will still have to work out 
// whether there are any matching records in your db
$sql = "select things FROM mytable where cat =" . $_GET['id'];

}else{

// now do your default action
// maybe show all things?
$sql = "select things FROM mytable";

}

// now action your sql statement. 


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Remove the comments. This could be run through PDO or Mysqli or Mysql functions, but I hope you get the general idea.

Quote:

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Originally Posted by Cups

You should work out first what you want to do if a cat has not been chosen:

Show all posts?
Show nothing, just a warning?

Likewise, if the cat id returns no records (presumably this should not happen, but could).

Show all posts?
Show nothing, just a warning?

A conditional check can be done like this.

PHP Code:

---


// use (int) to typecast the incoming cat variable to an integer
// if it is not able to cast it as an integer, it will return 0
// so only go on with the action 
// IF id is set AND id is recognised as an integer greater than 0

if( isset($_GET['id'] && (int)$_GET['id'] > 0){

// now an integer has been submitted, but you will still have to work out 
// whether there are any matching records in your db
$sql = "select things FROM mytable where cat =" . $_GET['id'];

}else{

// now do your default action
// maybe show all things?
$sql = "select things FROM mytable";

}

// now action your sql statement. 


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Remove the comments. This could be run through PDO or Mysqli or Mysql functions, but I hope you get the general idea.

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ough my God, it's really should work for me

thanks mate, you save my lot of time when i can't to do it.

hi mate,

i want to ask something else, i have done with this but i didn't make sure any security issues. so, just forget about that for while:

PHP Code:

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(isset($_GET['id']) ? $catId = $_GET['id'] : '');
    
    require_once 'inc/database.php';
    
    // Get all post from database
    $getPosts = "SELECT posts.*, posts_categories.*, categories.*
                 FROM (posts
                 INNER JOIN posts_categories
                       ON posts.post_id = posts_categories.postid)
                 INNER JOIN categories
                       ON posts_categories.catid = categories.cat_id
                 WHERE categories.cat_id = '$catId'";
    $nowPosts = $db->query($getPosts);
    
    if (!$nowPosts)
    {
        $title = 'Please try again later!';
        echo "<p class=\"dbError\">This category could not display. Please try again later.</p>";
    }
    else
    {
        if ($nowPosts->num_rows == 0)
        {
            $title = '404, Page Not Found!'; 

            // I will set $posts[] array manually in below like this
            /*
            $posts = array ( 
                     array (
                        'title' => '404, Page Not Found!',
                        'post_id' => '',
                        'post_title' => '404, Page Not Found!',
                        'post_createon' => '',
                        'post_content' => 'There is no any content in this category. 
                                           Please select another category.',
                         
                     ));
           */

        }
        else
        {
            while ($post = $nowPosts->fetch_assoc())
            {
                $title = $post['cat_label'];
             
                // here, i sent the content from database to $posts[] array
                $posts[] = $post;
            }
        }
    } 


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ok, according to my comment at the above code. i have sent all content that fetched from database (mysql) to $posts[] array. so i do this code in html template:

PHP Code:

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<?php

foreach ($posts as $post): ?>
                <h1>
                    <a href="post.php?id=<?php echo $post['post_id']; ?>" 
                       title="<?php echo $post['post_title']; ?>">                    
                    <?php echo $post['post_title']; ?>
                    </a>
                </h1>
                <p><em>Created Date: <?php echo $post['post_createon']; ?></em></p>
                <p><?php echo $post['post_content']; ?></p>
                <?php endforeach;
?>

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based on the above code, i must have some content in $posts[] array but when i have no any content in that category that mean no any content in $posts[] i will get error like this:

PHP Code:

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Notice:  Undefined variable: posts in /var/www/site/cat.php on line 117

Warning:  Invalid argument supplied for foreach() in /var/www/site/cat.php on line 117 


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so i think i can add any value in $posts[] array manually like first code in above that I've comment them. but, it's still make me disturbed cause it will make the title clickable and will go to this url:

PHP Code:

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http://localhost/site/post.php?id= 


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you can see that this title will redirect us to post.php page with no any [id] value :(

sorry for my bad english and explanation, but you can read my full code in attachment :)