how to make wordpress widget plugin

How to make a wordpress adserv plugin

Today we will make a widget that can do

1. Rotation display ad tags , track impression, compare impression at even

In order to do this, we need an internal table , and setup this table during plugin setup.

In the wp-config.php file, a WordPress site owner can define a database table prefix. By default, the prefix is “wp_”, but you’ll need to check on the actual value and use it to define your database table name. This value is found in the $wpdb->prefix variable. (If you’re developing for a version of WordPress older than 2.0, you’ll need to use the $table_prefix global variable, which is deprecated in version 2.1).

So, if you want to create a table called (prefix)liveshoutbox, the first few lines of your table-creation function will be:

global $wpdb;

$table_name = $wpdb->prefix . “ad_rotation”;

Since we going to use this table later during query, it make sense to create a function that return this table name for later reuse.

function get_tablename () {
global $wpdb;

$table_name = $wpdb->prefix . “ad_rotation”;
}

CREATE TABLE IF NOT EXISTS $table_name (
`id` int(11) NOT NULL AUTO_INCREMENT,
`type` int(11) NOT NULL COMMENT ‘ 300 900 -1’,
`banner` text NOT NULL,
`impression` int(11) NOT NULL,
`current_period_minute` int(11) NOT NULL,
`totalimpression` int(11) NOT NULL,
`enabled` int(11) NOT NULL,
PRIMARY KEY (`id`),
KEY `id` (`id`),
KEY `type` (`type`),
KEY `id_2` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=latin1;

A Good document from WordPress main dev site is https://codex.wordpress.org/Creating_Tables_with_Plugins. now, we have got the table creation SQL, we need to find a way to exec this sql when plug-in been installed.

So we come to today’s first wordpress built in function,

Examples
If you have a function called myplugin_activate() in the main plugin file at either

wp-content/plugins/myplugin.php or
wp-content/plugins/myplugin/myplugin.php
use this code:

function myplugin_activate() {

// Activation code here…
}
register_activation_hook( __FILE__, ‘myplugin_activate’ );

This will call the myplugin_activate() function on activation of the plugin.

If your plugin uses the singleton class pattern, add the activation hook like so:

class MyPlugin {
static function install() {
// do not generate any output here
}
}

register_activation_hook( __FILE__, array( ‘ad_rotation’, ‘_install’ ) );

https://codex.wordpress.org/Function_Reference/register_activation_hook

register_deactivation_hook( __FILE__, array( ‘CMAdChanger’, ‘_uninstall’ ) );

So we have our first code ready to test out. and we got an error.

One thing worth to poitn out, testing wordpress plug-in has do be done at wordpress sites and watch error output at the web error log ,

eg /var/log/apache2/cceye.com_error.log

2016/10/12 14:40:21 [error] 3514#0: *42992556 FastCGI sent in stderr: “PHP Fatal error: Call to undefined function get_tablename() in adrotation.php on line 68” while reading response header from upstream, client: 108.161.162.92, server: cceye.com, request: “GET /wp-admin/plugins.php?action=deactivate&plugin=adrotation%2Fadrotation.php&plugin_status=all&paged=1&s&_wpnonce=21cdd674ab HTTP/1.1”, upstream: “fastcgi://127.0.0.1:9000”, host: “www.cceye.com”

Ok, after fixing the the typo caused error, we move on next task: Show the form in backend to

1, allow add banner tag code in manage page
2, allow to show banner statics

let’s take a look of this https://codex.wordpress.org/Administration_Menus, ok, done. pretty long document. but here is the quick summary.

/** Step 2 (from text above). */
add_action( ‘admin_menu’, ‘my_plugin_menu’ );

/** Step 1. */
function my_plugin_menu() {
add_options_page( ‘Ad rotation Options’, ‘Ad Rotation’, ‘manage_options’, ‘my-unique-identifier’, ‘adrotation_options’ );
}

/** Step 3. */
function adrotation_options() {
if ( !current_user_can( ‘manage_options’ ) ) {
wp_die( __( ‘You do not have sufficient permissions to access this page.’ ) );
}
echo ‘

‘;
echo ‘

Here is where the form would go if I actually had options.

‘;
echo ‘

‘;
}

3, allow to select which type of tag to show in widget area.

Notice has right manage_options here is the list of all role and capabilite
https://codex.wordpress.org/Roles_and_Capabilities#update_core

Now I need to hold all the ad unit in memory so setting page can show it’s

ID,name,size,slot, TAG,IMPRESSION, 24 hours impression, total impression, enabled or not //size, slot

Now I have added admin menu, it’s time to insert data into the table we just created.

https://codex.wordpress.org/Class_Reference/wpdb

public function myAdminPage() {
// Echo the html here…
$adminpage=plugin_dir_path( __FILE__ ). ‘admin_ad.php’;

echo ‘This is the page contents ‘.$adminpage;

ob_start();
require_once $adminpage;
$content = ob_get_contents();
ob_end_clean();

echo $content;

}

prepare(
”
INSERT INTO $wpdb->postmeta
( post_id, meta_key, meta_value )
VALUES ( %d, %s, %s )
“,
10,
$metakey,
$metavalue
);
*/

#$tagcode = str_replace(“‘”, “\\'”, $_POST[‘bannercode’]);
#$name= str_replace(“‘”, “\\'”, $_POST[‘bannername’]);
/* $sqlquery=”INSERT INTO $tablename
(`id`, `name`, `size`, `type`, `banner`, `impression`, `current_period_minute`, `last_24h_impression`, `totalimpression`, `enabled`, `enabled_time`)
VALUES (NULL, %s ,%d ,%d,%s, ‘0’, ‘0’, ‘0’, ‘0’, ‘1’, CURRENT_TIMESTAMP)”;
*/
$sqlquery=”INSERT INTO $tablename (`id`, `name`, `size`, `type`, `banner`, `impression`, `current_period_minute`, `last_24h_impression`, `totalimpression`, `enabled`, `enabled_time`) VALUES (NULL, ‘”.$name.”‘,”.$size.”, “.$_POST[‘bannertype’].”,'”.$tagcode.”‘, ‘0’, ‘0’, ‘0’, ‘0’, ‘1’, CURRENT_TIMESTAMP)”;

#$sqlquery=$wpdb->prepare($sqlquery,$name,$_POST[‘bannertype’], $_POST[‘bannersize’],$tagcode);

$success=$wpdb->query($sqlquery);

#$success=$wpdb->query(“$sqlquery”);