Empty list

Set a list-typed column to the empty list

Ingredient Family: mappingIngredientsList

Outline Display: Set output {{columnName}} to the empty list

Details

The way to pin a list argument to no elements: a formula cannot write a list value, so an entry meaning “no elements” is written in a mapping’s object form as a literal YAML empty list (properties: []), which desugars to this ingredient. Only the empty list – a non-empty inline list has no mapping form and belongs in a list-typed tool parameter or a library wrapped endpoint’s Inputs. For an optional list column the empty value is None, so an API argument mapped this way is left out of the request; declare the endpoint parameter required when the service must see an explicit empty array.

Local scope

The parent slot binds these (look up the slot in the parent to see how):

• $inputsTable – The input table
• $mappingResult – A table that contains all mapped columns so far
• $matchTable – An optional table that contains columns that we may be trying to set values for

Settings

Required

• columnName : column of $matchTable or new (type filter: list type (optional or required))
  The list-typed field to set to the empty list
  Set ty only when columnName names a new column (not in $matchTable).

Optional

• value : constant value (type: type of columnName)
  Leave unset: the value is always the empty list