Date

Date fields use x.date() for date values (no time component).

x.date().label("Birth Date")

columnNameAliases

Adds alternate CSV header names for this field.

.columnNameAliases(aliases: string[])

• aliases lists header names that should map to this schema key.
• Aliases are used during column matching alongside the field key and label. They do not change the output object key.

label

Sets the user-facing label shown in the importer.

.label(text: string)

• text sets the label text.

description

Sets help text shown below the field.

.description(text: string)

• text sets the description text.

optional

Allows the field to be empty.

.optional()

• Empty optional values are delivered as null.
• The row object still includes the field key, e.g., { birthDate: null }.

default

Available after .optional().

.default(defaultValue: unknown | (() => unknown | Promise<unknown>))

• defaultValue can be a static value or a function used when the field is empty.
• Defaults apply to missing values, null, empty strings, and whitespace-only strings.
• When a default is used, it is returned directly instead of validating or refining the empty value.

output

Sets the output format template.

.output(template: string)

• template sets the output format template, e.g., "yyyy-MM-dd" or "MMM d, yyyy".