setRequired

SetRequired is a mutator name used across several programming libraries to enable a required constraint on a value, field, or parameter. While the exact implementation varies by language, the common purpose is to mark an element as mandatory so that absence or emptiness is considered invalid.

In form validation and data modeling, setRequired typically toggles an internal flag or updates a validation schema. Calling setRequired(true) signals that the corresponding value must be provided, while setRequired(false) can remove the constraint. Some libraries accept an options object with a custom error message, for example setRequired({ required: true, message: 'This field is required' }). Others implement it as a fluent API, such as field.setRequired(true).

Effects of the constraint include client-side checks, user interface cues (such as highlighting the field or displaying an error message), and server-side validation if the constraint is included in a submission schema. The behavior may differ for strings, numbers, or composite values; for instance, empty strings may be treated as missing even if a value is present in another form.

Common considerations include localization of error messages, interaction with optional fields, default values, and how required interacts with more advanced validators like minLength or pattern. It is important to align setRequired with the overall data model and backend validation to avoid inconsistent validation rules.

See also: validation, data constraints, schema builders.