Custom Fields

Documentation for version 1.4 or later

Regular meta

The Custom Fields extension supports meta of three object types:

Posts
Users
Comments

Here are the examples with equivalents in get_****_meta()

{postmeta {post_ID} metakey}
// equivalent of:
// get_post_meta( $post_id, $metakey, true );

{usermeta {user_ID} metakey}
// equivalent of:
// get_user_meta( $user_id, $metakey, true );

{commentmeta {comment_ID} metakey}
// equivalent of:
// get_comment_meta( $comment_id, $metakey, true );

Note that {post_ID} or {user_ID} or {comment_ID} part is the object ID which can be static (like just 365783) or can be a merge tag. If you are using merge tags for this part, like in the examples, please make sure you can see this merge tag in the sidebar. So if you choose the Book updated trigger, the {post_ID} will become {book_ID}.

Advanced Custom Fields meta

Any ACF field value can be retrieved with the regular meta merge tags, but sometimes you'd want to let ACF format the data for you.

Very similar to regular meta you can use it like this:

{acf {post_ID} my_field_slug}
{acf comment_{comment_ID} fieldname}
{acf user_{user_ID} fieldname}
{acf term_{term_ID} fieldname}

Which is an equivalent of:

get_field( $fieldname, $item_id );

You can access the first-level array key as well

Giving an example, you can have a field of type User and return format of User array. Your meta will look like this:

Array
(
    [ID] => 1
    [user_firstname] => Panda
    [user_lastname] => Bear
    [nickname] => admin
    [user_nicename] => admin
    [display_name] => Panda Bear
    [user_email] => admin@example.com
    [user_url] => 
    [user_registered] => 2019-03-14 10:46:17
    [user_description] => 
    [user_avatar] => <img alt='' src='http://2.gravatar.com/avatar/21c9a0124feee215cb7c5759f7e6670b?s=96&#038;d=mm&#038;r=g' srcset='http://2.gravatar.com/avatar/21c9a0124feee215cb7c5759f7e6670b?s=192&#038;d=mm&#038;r=g 2x' class='avatar avatar-96 photo' height='96' width='96' />
)

To access the user_email key, you just need to do it like this:

{acf {post_ID} user_field:user_email}

Access array keys

Getting the meta often means you need to work with arrays. Deeper levels can be easily accessed with : character.

Let's consider an example, where you have this array in your meta:

Array
(
    [date] => 2019-03-14 10:46:17
    [accepted] => 1
    [email] => 'user@example.com'
)

To access the email key you just need to pass the array key after the colon:

{postmeta {post_ID} metakey:email}

This will work with any type of meta.

Giving the ACF example, you can have a field of type User and return format of User array. Your meta will look like this:

Array
(
    [ID] => 1
    [user_firstname] => Panda
    [user_lastname] => Bear
    [nickname] => admin
    [user_nicename] => admin
    [display_name] => Panda Bear
    [user_email] => admin@example.com
    [user_url] => 
    [user_registered] => 2019-03-14 10:46:17
    [user_description] => 
    [user_avatar] => <img alt='' src='http://2.gravatar.com/avatar/21c9a0124feee215cb7c5759f7e6670b?s=96&#038;d=mm&#038;r=g' srcset='http://2.gravatar.com/avatar/21c9a0124feee215cb7c5759f7e6670b?s=192&#038;d=mm&#038;r=g 2x' class='avatar avatar-96 photo' height='96' width='96' />
)

To access the user_email key, you just need to do it like this:

{acf {post_ID} user_field:user_email}

Multidimensional arrays

But what in case you have a multidimensional array like this?

Array
(
    [user] => Array
    (
        [user_firstname] => Panda
        [user_lastname] => Bear
        [user_email] => admin@example.com
    )
)

Easy! Just pass the nested keys after another colon:

{... user_field:user:user_email}

Same story with numeric arrays:

Array
(
    [0] => Array
    (
        [user_firstname] => Panda
        [user_lastname] => Bear
        [user_email] => admin@example.com
    )
)

{... user_field:0:user_email}

Pipelines

Sometimes the value in meta is not exactly in a form you'd like. The most common scenario is having a post or user ID saved in the meta while you want to display a post_title or display_name.

Each pipe is processing the value and manipulate its representation. You can think about it like this:

Initial value -> replace -> reshape -> replace -> format

So the initial value of User ID can be replaced with a whole User object and this object can be formatted as JSON.

Pipes can be mixed together and each pipe can be used with the array accessors. They work with ACF and regular meta Merge Tags. See the example.

All supported pipelines:

post

Gets the post object as an array.

|post

postmeta

Gets the post meta.

|postmeta,$key,$single

$key and $single arguments are optional. If you omit the $key argument all the post meta is retrieved. This is an equivalent of get_post_meta function.

$single will evaluate to boolean, so you can write any of: on, true, 1, yes, etc.

term

Gets the term object as an array.

|term

termmeta

Gets the term meta.

|termmeta,$key,$single

$key and $single arguments are optional. If you omit the $key argument all the term meta is retrieved. This is an equivalent of get_term_meta function.

$single will evaluate to boolean, so you can write any of: on, true, 1, yes, etc.

user

Get the user object as an array.

|user

usermeta

Gets the user meta.

|usermeta,$key,$single

$key and $single arguments are optional. If you omit the $key argument all the user meta is retrieved. This is an equivalent of get_term_meta function.

$single will evaluate to boolean, so you can write any of: on, true, 1, yes, etc.

pluck

Plucks the values from the collection

|pluck,$key

$key argument is required. This is an equivalent of wp_list_pluck function.

Plucking the name key from this array:

Array
(
    [0] => Array
    (
        [name] => John Doe
    )
    [1] => Array
    (
        [name] => Jane Doe
    )
)

Will result with:

Array
(
    [0] => John Doe
    [1] => Jane Doe
)

join

Joins the array values into a comma-separated string.

|join

Joining an array:

Array
(
    [0] => John Doe
    [1] => Jane Doe
)

Will result with:

John Doe, Jane Doe

first

Gets the first element of an array.

|first

Getting the first element of an array:

Array
(
    [0] => John Doe
    [1] => Jane Doe
)

Will result with:

John Doe

last

Gets the last element of an array.

|last

Getting the last element of an array:

Array
(
    [0] => John Doe
    [1] => Jane Doe
)

Will result with:

Jane Doe

bool

Formats the boolean value in the desired way.

|bool,$true,$false

$true String to return when the value is evaluated to true
$false String to return when the value is evaluated to false

Example:

|bool,Active and ready to go,Disabled

json

Formats the value as json.

|json

Value formatting

String values are always displayed as literal strings. No HTML is escaped.

If the returned value is an array with a single item, it's automatically unwrapped and the first item is returned.

Array values are represented with print_r() function and wrapped with <pre> tags. Example:

Array
(
    [0] => Array
    (
        [name] => John Doe
    )
    [1] => Array
    (
        [name] => Jane Doe
    )
)

Boolean values are represented as Yes or No by default.

You can change the format by using the formatting pipes, like bool, join, or json.

Examples

Post has a related_post field (stored post ID) where another related post can be selected. The related post has a field where owner can be selected and this returns the user ID. To get this user email:

{postmeta {post_ID} related_post|postmeta,owner,true|user:user_email}

Explanation:

{postmeta {post_ID} related_post - gets the initial value of the related post, post ID is retrieved
|postmeta,owner,true - related post ID is used to get the meta key owner and true means the single value should be returned. We get the User ID.
|user:user_email - user ID is used to get the whole user representation. We access the user_email array key to get the email

Limitations

The plugin cannot handle iterators. Ie. if you want to map an array of users. In other words, it's not possible to work on the collections. The subsequent pipes are meant to reduce the data to a single value.

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