l.oneOf()

Passes when the value equals one of values, compared with ==. The output is the matching allowed value, so l.oneOf([1, 2]) turns an input of 1.0 into 1. Returns an OneOfValidator<T, T?>. Use it for enums serialized by name or by @JsonValue.

Signature

OneOfValidator<T, T?> oneOf<T extends Object>(List<T> values, {String? message, MessageBuilder? messageBuilder})

Parameters

Parameter	Type	Meaning
values	List<T>	The allowed values. Must not be empty; an empty list throws ArgumentError when the validator is built.
message	String?	Replaces the default error message.
messageBuilder	MessageBuilder?	Builds the message from the issue. message wins when both are given. See Message builders.

Issue

Code notOneOf. Default message: value must be one of: admin, member, listing the allowed values, with params['allowed']. value is replaced by the field name when there is one.

Code generation

An enum parameter maps to l.oneOf([...]) with the enum’s serialized values: the names, or @JsonValue, @JsonEnum(fieldRename:, valueField:), @MappableEnum and @MappableValue when present.

Example

Hand-written

final role = l.oneOf(['admin', 'member']);

Generated

enum Role { admin, member }

@Default(Role.member) Role role, // l.oneOf(["admin", "member"])
required Role role,              // l.oneOf(["admin", "member"]).required()

role.validate(input)+2-2

1. +valid: 'admin'
2. -invalid: 'owner'value must be one of: admin, member
3. -invalid: 'Admin'value must be one of: admin, member
4. +valid: null

The output is the allowed value, not the input:

ValidationSuccess(data: 1)
ValidationSuccess(data: admin)