Takes a post ID and returns the database record for that post. You can specify, by means of the $output parameter, how you would like the results returned.Retrieves all category IDs.

<?php get_post( $post_id, $output ); ?> 

$post_id

(integer) (required) The ID of the post you'd like to fetch. You must pass a variable containing an integer (e.g. $id). A literal integer (e.g. get_post(7)) will cause a fatal error (Only variables can be passed for reference or Cannot pass parameter 1 by reference).

Default: None

$output

(string) (optional) How you'd like the result.

• OBJECT - (default) returns an object
• ARRAY_A - Returns an associative array of field names to values
• ARRAY_N - returns a numeric array of field values

Default: OBJECT

In case of failure, this function returns null.

The fields returned are:

ID

(integer) The post ID

post_author

(integer) The post author's ID

post_date

(string) The datetime of the post (YYYY-MM-DD HH:MM:SS)

post_date_gmt

(string) The GMT datetime of the post (YYYY-MM-DD HH:MM:SS)

post_content

(string) The post's contents

post_title

(string) The post's title

post_category

(integer) The post category's ID. Note that this will always be 0 (zero) from wordpress 2.1 onwards. To determine a post's category or categories, use get_the_category().

post_excerpt

(string) The post excerpt

post_status

(string) The post status (publish|pending|draft|private|static|object|attachment|inherit|future|trash)

comment_status

(string) The comment status (open|closed|registered_only)

ping_status

(string) The pingback/trackback status (open|closed)

post_password

(string) The post password

post_name

(string) The post's URL slug

to_ping

(string) URLs to be pinged

pinged

(string) URLs already pinged

post_modified

(string) The last modified datetime of the post (YYYY-MM-DD HH:MM:SS)

post_modified_gmt

(string) The last modified GMT datetime of the post (YYYY-MM-DD HH:MM:SS)

post_content_filtered

(string)

post_parent

(integer) The parent post's ID (for attachments, etc)

guid

(string) A link to the post. Note: One cannot rely upon the GUID to be the permalink (as it previously was in pre-2.5), Nor can you expect it to be a valid link to the post. It's merely a unique identifier, which so happens to be a link to the post at present.

menu_order

(integer)

post_type

(string) (post|page|attachment)

post_mime_type

(string) Mime Type (for attachments, etc)

comment_count

(integer) Number of comments

To get the title for a post with ID 7:

<?php
$my_id = 7;
$post_id_7 = get_post($my_id); 
$title = $post_id_7->post_title;
?> 

Retrieves all category IDs.

<?php get_all_category_ids() ?>

None.

To print a list of categories by id: name

<?php
$category_ids = get_all_category_ids();

foreach($category_ids as $cat_id) {
  $cat_name = get_cat_name($cat_id);
  echo $cat_id . ': ' . $cat_name;
}
?> 

This Conditional Tag checks if an Author archive page is being displayed. This is a boolean function, meaning it returns either TRUE or FALSE.

<?php is_author($author); ?>

$author

(string) (optional) Author ID or Author Nickname
Default: None

(boolean)
   True on success, false on failure.

is_author();
// When any Author page is being displayed.

is_author('4');
/********************************************
When the archive page for Author
number (ID) 4 is being displayed.
********************************************/

is_author('Vivian');
/********************************************
When the archive page for the Author with
Nickname "Vivian" is being displayed.
********************************************/

is_author('john-jones');
/********************************************
When the archive page for the Author with
Nicename "john-jones" is being displayed.
********************************************/

is_author(array(4,'john-jones','Vivian'));
/***********************************************
// When the archive page for the author is 
either user ID 4, or user_nicename "john-jones",
or nickname "Vivian".  Note: the array ability
was added at Version 2.5.
***********************************************/

Schedules a hook which will be executed once by the WordPress actions core at a time which you specify. The action will fire off when someone visits your WordPress site, if the schedule time has passed.

<?php
wp_schedule_single_event(time(), 'my_schedule_hook'); 
?> 

Note that scheduling an event within 10 minutes of an event of the same name will be ignored, unless you pass unique values for $args to each scheduled event. See Function_Reference/wp_next_scheduled for more information.

Attempts to schedule an event after an event of the same name and $args will also be ignored.

$timestamp

(integer) (required) The time you want the event to occur. This must be in a UNIX timestamp format.

Default: None

$hook

(string) (required) The name of an action hook to execute.

Default: None

$args

(array) (optional) Arguments to pass to the hook function(s)

Default: None

(false | null)
    False if the event was cancelled by a plugin, Null otherwise.

Schedule an event one hour from now

function do_this_in_an_hour() {
// do something
}
add_action('my_new_event','do_this_in_an_hour');

// put this line inside a function, 
// presumably in response to something the user does
// otherwise it will schedule a new event on every page visit

wp_schedule_single_event(time()+3600, 'my_new_event');

// time()+3600 = one hour from now.

Retrieve or display nonce hidden field for forms.

The nonce field is used to validate that the contents of the form came from the location on the current site and not somewhere else. The nonce does not offer absolute protection, but should protect against most cases. It is very important to use nonce fields in forms.

If you set $echo to false and set $referer to true, then you will need to retrieve the referer field using wp_referer_field(). If you have the $referer set to true and are echoing the nonce field, it will also echo the referer field.

The $action and $name are optional, but if you want to have better security, it is strongly suggested to set those two parameters. It is easier to just call the function without any parameters, because validation of the nonce doesn't require any parameters, but since crackers know what the default is it won't be difficult for them to find a way around your nonce and cause damage.

The input name will be whatever $name value you gave. The input value will be the nonce creation value.

<?php
wp_nonce_field( $action, $name, $referer, $echo ) 
?>

$action

(string) (optional) Action name. This is the unique identifier for this nonce. Optional but recommended.

Default: -1

$name

(string) (optional) Nonce name. This is the name of the hidden field form variable (once submitted you can access the nonce via $_POST[$name]).

Default: "_wpnonce"

$referer

(boolean) (optional) default true. Whether to set the referer field for validation.

Default: true

$echo

(boolean) (optional) default true. Whether to display or return hidden form field.

Default: true

(string)
    Nonce field.

While less secure than the examples that follow, this is the simplest implementation which omits all arguments. In your form add the following:

<?php wp_nonce_field(); ?>

It's better to name your action and nonce in your form. Enter values for the first and second arguments to print the necessary hidden field:

<form method="post">
   <!-- some inputs here ... -->
   <?php
   wp_nonce_field('name_of_my_action',
                  'name_of_nonce_field'); 
   ?>
</form>

Then in the page where it is being submitted to, you may verify it using the wp_verify_nonce() function. Notice that you have to manually retrieve the nonce (from the $_POST array in this example), and the name of the action is the 2nd parameter instead of the first:

<?php
if ( empty($_POST) || 
    !wp_verify_nonce($_POST['name_of_nonce_field'],
                            'name_of_my_action') )
{
   print 'Sorry, your nonce did not verify.';
   exit;
}
else
{
   // process form data
}

If you are submitting and processing the form inside the WP administration area, you may verify the nonce using the check_admin_referer() function:

<?php
/****************************************
if this fails, check_admin_referer()
will automatically print a "failed" page and die.
****************************************/
if ( !empty($_POST) && 
     check_admin_referer('name_of_my_action',
                         'name_of_nonce_field') )
{
   // process form data
}

This function is a method of the $wp_admin_bar global object (see: WP_Admin_Bar), and can be used to add a new item to the Toolbar. You can also use it to change the properties of an item that is already in the Toolbar.

The Toolbar replaces the Admin Bar since WordPress Version 3.3.

Toolbar items are also called "nodes". Nodes can be parents for other nodes, which creates dropdown menus. Group nodes together with add_group() to create distinct sections in a Toolbar menu.

Note: This function is a method of the WP_Admin_Bar class and $wp_admin_bar global object, which may not exist except during the 'admin_bar_menu' or 'wp_before_admin_bar_render' hooks.

<?php $wp_admin_bar->add_node( $args ); ?>

$args

(array) (required) An array of arguments.

Default: None
 

Arguments:

id

(string) (required) The ID of the node.

Default: false

title

(string) (optional) The text that will be visible in the Toolbar. Including html tags is allowed.

Default: false

parent

(string) (optional) The ID of the parent node.

Default: false

href

(string) (optional) The 'href' attribute for the link. If 'href' is not set the node will be a text node.

Default: false

group

(boolean) (optional) This will make the node a group (node) if set to 'true'. Group nodes are not visible in the Toolbar, but nodes added to it are. See add_group().

Default: false

meta

(array) (optional) An array of meta data for the node.

Default: array()

• 'html' - The html used for the node.
• 'class' - The class attribute for the list item containing the link or text node.
• 'onclick' - The onclick attribute for the link. This will only be set if the 'href' argument is present.
• 'target' - The target attribute for the link. This will only be set if the 'href' argument is present.
• 'title' - The title attribute. Will be set to the link or to a div containing a text node.
• 'tabindex' - The tabindex attribute. Will be set to the link or to a div containing a text node.

None.

Add a Page to the Toolbar

This example will add a Page with a "my-toolbar-page" class to the Toolbar. It will be a top level item because the 'parent' argument is not set (it has no parent node). Put this in your theme's functions.php file.

add_action( 'admin_bar_menu', 'toolbar_link_to_mypage', 999 );

function toolbar_link_to_mypage( $wp_admin_bar ) {
  global $wp_admin_bar;
  $args = array(
    'id' => 'my_page',
    'title' => 'My Page',
    'href' => 'http://mysite.com/my-page/',
    'meta' => array('class' => 'my-toolbar-page')
  );

  $wp_admin_bar->add_node($args);
}

This Conditional Tag checks if the main page is being displayed. This is a boolean function, meaning it returns either TRUE or FALSE.

Note: WordPress 2.1 handles this function differently than prior versions - See static Front Page. If you select a static Page as your frontpage (see is_front_page()), this tag will be applied to your "posts page".

<?php is_home(); ?>

None.

(boolean)
   True on success, false on failure.

The following example can be used in your sidebar to display different content when displaying home page.

<?php
if ( is_home() ) {
    // This is a homepage
} else {
    // This is not a homepage
}
?>