Lax Fields

A lax field is both an input and output field whose value may or may not be provided at creation. When missing, its default value is used.

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Allowed values

Restrict a lax field to a fixed set of values with .allow(). The array must contain at least two values, and the static default must be one of them.

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Use .allowError() to customize the error message:

b.lax("status", "draft")
  .allow(["draft", "published"])
  .allowError((value, allowed) => `"${value}" is not a valid status`);

Default values

The default value can be static or a resolver function. Resolvers receive the creation context:

b.lax("timezone", "UTC");
b.lax("locale", ({ options }) => options.locale ?? "en");

If a resolver throws, the field value becomes null.

Validation

Use .validate() to run validators at creation and .reValidate() to run different validators on update. If reValidate is omitted, the create validator is reused.

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Conditional required

A lax field can be made conditionally required with .required(handler). The handler receives the operation context and returns a tuple [isRequired, errorMessage].

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.required() is mutually exclusive with .readonly(), .ignoreInit(), and .ignoreUpdate().

Readonly

readonly() is only available when the default is a static value. It locks the field once its current value has diverged from the default.

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.readonly() is mutually exclusive with .required(), .ignoreInit(), and .ignoreUpdate().

Ignore rules

• .ignore(resolver) — ignore the field during create and update when the resolver returns true.
• .ignoreInit() — ignore the field only during create.
• .ignoreUpdate() — ignore the field only during update.

These are mutually exclusive with .readonly() and .required().

b.lax("role", "guest").ignore(({ input }) => input.role === "admin");

Hooks

Lax fields support onDelete, onSuccess, and onFailure listeners.

API summary

Method	Description
lax(name, defaultValue)	Create a lax field with a static default or resolver.
allow(values)	Restrict to at least two allowed values.
allowError(error)	Customize the not-allowed error.
validate(validator)	Validator for create (and update if no reValidate).
reValidate(validator)	Validator used during updates.
required(handler)	Conditionally require the field.
readonly()	Lock after divergence; only with a static default.
ignore(resolver)	Ignore field when resolver returns true.
ignoreInit()	Ignore field at creation.
ignoreUpdate()	Ignore field at update.
onDelete(handler)	Listener invoked by model.delete.
onFailure(handler)	Listener invoked after validation failure.
onSuccess(handler)	Listener invoked after a successful create/update.