{ensureitem:existing_id:template_long_item_id:field_1:new_value_1:...}

An existing item ID to reuse. If this is a valid 32-character item ID, ensureitem returns it unchanged and stops - nothing is created or modified, and the remaining arguments are ignored. If it is empty or not a valid ID, ensureitem creates a new item from the template instead. Typically you pass the result of an ids lookup here so the item is reused when found and created when missing.

ID of the template item to copy when a new item must be created (used only when existing_id is empty or invalid). The template is an ordinary item - you may keep it in a Holding or Trash bin - and it must live in a slice related to the current slice. The new item inherits the template field values except seo (cleared) and status_code (set active). If the template ID is missing or not found, no item is created and the result is empty.

A field ID (16 characters, for example headline........) whose value to set on the newly created item. Append a plus sign to add a value instead of replacing it (relation........+). Field/value arguments come in pairs and repeat; they apply only on the create branch and are ignored when existing_id already points to an item.

The value for the preceding field_id. A single value is plain text, multiple values are written as a JSON array, for example ["enviro","social"]. Paired with field_id and repeatable; ignored when an existing item is returned.