Fires immediately before meta of a specific type is added. The dynamic portion of the hook, `$meta_type`, refers to the meta object type (comment, post, term, or user).

Parameters

.

( 3.1.0 ) . .

( int ) $object_id ID of the object metadata is for. . . .

$meta_key

( string ) Metadata key. . . .

( mixed ) $_meta_value Metadata value. Serialized if non-scalar. . . .