About Collection Fields

Fields define the structure of a collection. They act as the collection's columns, describing what each item can store and what type of data each value is.

You can manage fields in the Wix Data view, in the Code tab, in the CMS dashboard, or in code with the Data Collections API. To add a field to an existing collection, see Add a Field to a Collection.

Field IDs

Each field has a unique ID that you use to refer to it in code. A field's ID can differ from the display name that the CMS dashboard shows.

To copy a field's ID, see Find Collection and Field IDs.

Field types

Each field has a type that describes the kind of data it holds. The CMS groups field types into these categories:

• Essentials: Basic types, such as text, numbers, dates, and booleans.
• Media: Images, audio, video, and documents.
• Time and location: Times, locations, and addresses.
• JavaScript: Objects and arrays.

Field types provide structure but aren't strictly enforced. An item can store a value that doesn't match its field's type, though this isn't recommended.

Reference fields

Reference fields link items in different collections. A reference field stores the ID of an item in another collection, so you can connect related data.

A single reference field links to one item. A multi-reference field links to several items in the other collection.

To add a reference field to a collection, see Field types.

System fields

Every collection automatically includes these system fields:

• _id: The item's unique ID.
• _createdDate: When the item was created.
• _updatedDate: When the item was last changed.
• _owner: The ID of the visitor or member who created the item.

The CMS manages system fields, and they're mostly read-only. You can set _id to a unique value of your choice when you add a new item with Insert Data Item or Save Data Item. You can also change _owner if the caller has site-owner permissions.

Undefined fields

An undefined field is a field that appears in a collection's items but isn't part of the collection's structure. This can happen when you add an item with the Data API that includes a key the collection doesn't define, or when you restore a previous version of a site.

Undefined fields give you flexibility while a data structure evolves, but it's best practice to define all fields properly in your collection.

See also

• About Collections
• Find Collection and Field IDs