How to Use Custom Post Meta in WordPress Plugin
Posted on 20th June 2023
Please note that this is a guideline and not an exact word count.
How to Use Custom Post Meta in WordPress Plugin
As a WordPress plugin developer, you may be wondering how you can take advantage of custom post meta to provide more features and functionality to your users. Custom post meta allows you to add arbitrary data to a post, which can then be used in your plugin to provide additional functionality. In this article, we’ll show you how to use custom post meta in a WordPress plugin.
First, you need to add the custom post meta to the post. You can do this using the add_post_meta() function. The first argument is the post ID, the second argument is the key of the custom field, and the third argument is the value of the custom field. For example, let’s say we want to add a custom field called “color” to a post with the ID of 123. We would use the following code:
add_post_meta( 123, ‘color’, ‘red’ );
Now that the custom field has been added, we can retrieve it in our plugin using the get_post_meta() function. This function takes the post ID as its first argument, the key of the custom field as its second argument, and a boolean value as its third argument. If the third argument is set to true, this function will return an array of all values for the specified key. If the third argument is set to false, this function will return the first value for the specified key. In our example, we would use the following code to get the value of the “color” custom field:
$color = get_post_meta( 123, ‘color’, true );
This code would return an array of all values for the “color” custom field. If we only wanted the first value, we would use the following code:
$color = get_post_meta( 123, ‘color’, false );
This code would return the string “red”, which is the first value for the “color” custom field.
In addition to retrieving values from a custom field, you can also update and delete values using the update_post_meta() and delete_post_meta() functions, respectively. These functions work similarly to the add_post_meta() function, but take an additional fourth argument: the value you want to update or delete. For example, let’s say we want to update the “color” custom field to “blue”. We would use the following code:
update_post_meta( 123, ‘color’, ‘blue’ );
If we wanted to delete the “color” custom field, we would use the following code:
delete_post_meta( 123, ‘color’ );
Custom post meta is a powerful tool that can be used to add arbitrary data to a post. In this article, we’ve shown you how to add, retrieve, update, and delete custom post meta.
Assuming you have a basic understanding of how to create a WordPress plugin, we will now take a look at how to use custom post meta in a WordPress plugin.
WordPress stores a great deal of data about each post in a custom post meta table. This data is stored as key/value pairs. The key is the name of the piece of data, and the value is, well, the value of the data.
To get at this data, you need to use the WordPress get_post_meta() function. This function takes three parameters: the post ID, the key, and a Boolean value that specifies whether or not to return a single value or an array of values.
Here’s an example of how to use get_post_meta():
$post_id = 123;
$key = ‘my_custom_field’;
$single = true;
$custom_field = get_post_meta( $post_id, $key, $single );
In the example above, we are retrieving the value of the my_custom_field custom field for the post with an ID of 123. We are specifying that we only want to retrieve a single value, so if there are multiple values for this field, only the first one will be returned.
If, on the other hand, we set the $single parameter to false, we would get an array of all the values for this field, even if there is only one:
$post_id = 123;
$key = ‘my_custom_field’;
$single = false;
$custom_field = get_post_meta( $post_id, $key, $single );
So, how do you actually use this data once you’ve retrieved it?
Well, that depends on what the data is. If it’s just a simple string, you can output it directly:
echo $custom_field;
If the data is more complex, such as an array of values, you will need to process it further before outputting it.
Now that we’ve seen how to retrieve custom post meta data, let’s take a look at how to update it.
The WordPress function for updating custom post meta data is update_post_meta(). This function takes four parameters: the post ID, the key, the value, and a Boolean value that specifies whether or not to add the key/value pair if it doesn’t already exist.
Here’s an example of how to use update_post_meta():
$post_id = 123;
$key = ‘my_custom_field’;
$value = ‘This is my new value’;
$prev_value = ‘This is my old value’;
update_post_meta( $post_id, $key, $value, $prev_value );
In the example above, we are updating the my_custom_field custom field for the post with an ID of 123. We are setting the new value to ‘This is my new value’. We are also specifying the old value (‘This is my old value’) so that WordPress will only update the field if the current value is what we expect it to be.
If you don’t need to specify a previous value, you can just leave that parameter out:
$post_id = 123;
$key = ‘my_custom_field’;
$value = ‘This is my new value’;
update_post_meta( $post_id, $key, $value );
And that’s all there is to it! Using custom post meta is a great way to add extra data to your WordPress posts.
If you want to add some extra data to a post, you can use custom post meta. This is data that is not part of the main post content, but is still stored in the database. You can add as much or as little custom post meta as you want, and it can be used to store anything from simple data like ratings to more complex data like user preferences.
To add custom post meta to a plugin, you first need to register the meta key with the WordPress. To do this, you can use the register_meta() function. This function takes three arguments: the meta key, the object type, and an array of args. The object type can be either ‘post’ or ‘user’.
Once you have registered the meta key, you can then use the add_post_meta() or update_post_meta() functions to add or update the meta data for a post. These functions take three arguments: the post ID, the meta key, and the meta value.
You can also use the get_post_meta() function to retrieve the value of a specific meta key for a post. This function takes two arguments: the post ID and the meta key.
So, for example, let’s say you want to add a ‘rating’ meta key to store the rating for a post. You would first need to register the meta key with WordPress:
‘string’,
‘single’ => true,
‘show_in_rest’ => true,
) );
?>
Then, you can use the add_post_meta() or update_post_meta() functions to add or update the rating for a post:
Finally, you can use the get_post_meta() function to retrieve the rating for a post:
