Expose#

expose lists the columns the owner chooses to make available, along with their data types.

For an orders dataset with these columns:

order_id	supplier_id	amount
1	globex	120
2	initech	80

The owner can expose only order_id and amount:

expose:
  - {name: order_id, type: int64}
  - {name: amount, type: int64}

supplier_id is left out of the output. It remains available to rules that need to identify the supplier for each order.

Column names and types#

Each entry has a name matching a column in the data and a type describing its values. For a dataset containing order identifiers, status text, and a delivery flag:

expose:
  - {name: order_id, type: int64}
  - {name: status, type: utf8}
  - {name: delivered, type: bool}

Type	Values
`int64`	Whole numbers, such as `120`.
`utf8`	Text, such as `shipped`.
`bool`	`true` or `false`.
`float64`	Floating-point numbers, such as `12.5`.

Parcel checks that the columns exist, their names are unique, and their types match. If a rule replaces a column’s value, its output must match the type declared here. For more details, see Column types.

expose is required unless inherited from a parent contract. See Contract inheritance.