update_user_meta()

update_user_meta() — Updates user meta field based on user ID. Use the $prev_value parameter to differentiate between meta fields with the same key and user ID. If the meta field for the user does not exist, it will be added. For historical reasons both the meta key and the meta value are expected to be “slashed” (slashes escaped) on input.

Inputs: $user_id (int): User ID. $meta_key (string): Metadata key. $meta_value (mixed): Metadata value. Must be serializable if non-scalar. $prev_value (mixed): Optional. Previous value to check before updating. If specified, only update existing metadata entries with this value. Otherwise, update all entries. Default empty.

Returns int|bool: Meta ID if the key didn’t exist, true on successful update, false on failure or if the value passed to the function is the same as the one that is already in the database.