insert image alongwith with custom data via a frontend form

Question

I use wordpress as a cms. I wanted to insert custom data via a form from the frontend in my wordpress site and then echo it on a page somewhere. After learning from here and there I am able to put together a codes below which works. Here is a code of what my form looks like currently.

<form id="costing_submit_form" action="http://somesite.com/..../process-costing.php" method="post">
<input type="hidden" name="costing_submit_date" value="<?php echo $costing_submit_date;?>"/>        
<input type="text" id="costing_submit_title" name="costing_submit_title" size="90%" maxlength="150" /><br>
<textarea id="costing_submit_description" name="costing_submit_description" size="90%" cols="60" rows="10 tabindex="15" maxlength="2000" rows="20" required="" /></textarea>    
<input type="submit" class="costing_submit_button" name="costing_submit_button" value="SUBMIT COSTING" />
</form>

At this point I am able to insert the data and also display it in the frontend using $wpdb. This part of the code is in process-costing.php which inserts the data in the database table.

global $wpdb; 
    require_once('../../../wp-load.php');
    $costing_submit_date        = strip_tags($_POST['costing_submit_date']);
    $costing_submit_title       = strip_tags($_POST['costing_submit_title']);
    $costing_submit_description = strip_tags($_POST['costing_submit_description']);
    $table_name = $wpdb->prefix . "costing";
    $wpdb->insert( $table_name, array(
    'costing_date' => $costing_submit_date,
    'costing_title' => $costing_submit_title,
    'costing_description' => $costing_submit_description,
    ));

Now, I would like to add an image to every entry made, so how do I go about it. If not a complete solution kindly give me a road-map as to what I should be doing or following, what specific functions should I be using ? Even if I am able to upload the image. My main concern is how do I associate the uploaded image to that particular entry...something like post-thumbnail perhaps ? If possible I would also like to assign a particular folder to these images. Thanks in advance.

Answer 1

For Image uploads you can use wp_handle_upload(). Adding attachments can be done through wp_insert_attachment(). The association between attachment and your costing item can be achieved through update_post_meta(). Aside: Meta keys starting with an underscore _ are not showing up in WordPress UI.

You code could be looking like this:

<?php
$my_costing_id; /* contains the id of the corresponding item in your costing table */

// create attachment
$attachment_data = array(
    'post_title' => 'An Image', 
    'post_content' => 'An Image', 
    'post_status' => 'publish', 
    'post_mime_type' => 'image/jpeg', 
);
$attachment_id = wp_insert_attachment($attachment_data , 'path/to/uploaded/file.jpg' );

update_post_meta( $attachment_id , '_costing_id' , $my_costing_id );

To get the $costing_id corresponding to a known $attachment_id simply use get_post_meta. To get the $attachment_id of a corresponding $costing_id, you will need to write your own SQL query and pass it to $wpdb:

<?php
$attachment_id = $wpdb->get_var( $wpdb->prepare("SELECT post_id FROM $wpdb->postmeta WHERE meta_value=%d AND meta_key=%s") , $costing_id , '_costing_id' );

Hope this helps,

regards j.