Annotations

Hint

Usage

The hint field of a form field can be specified using the @Hint annotation. Note this only allows string values.

Example

data class MyFormModel(
    @Hint("Value")
    var value: String? = null,
)

...

Form<MyFormModel> {

    // Displays a Text field with the 'Value' hint
    FormTextField(MyFormModel::value)
}

Validators

Pre-implemented

Pre-implemented validators, such as NotEmptyValidator all have sister annotations in the library. You can find this annotation by removing the Validator part of the class name. For example, NotEmptyValidator -> @NotEmpty

Most validation annotations take an error message, and other validation parameters where possible. They also often specify a default error message which is the same as their class counterparts. In some cases this may appear empty, but this is only to use Composable functions when they are called (for example the @DateBefore requires access to the LocalDateFormat LocalComposition)

Example

data class MyFormModel(

    @Hint("Value")
    @NotEmpty(error = "Value is Required")
    var value: String? = null,
)

...

Form<MyFormModel> {

    // Displays a Text field which cannot be empty
    FormTextField(MyFormModel::value)
}

Custom - Simple

You can also use your own validators in annotations, with the @Validator annotation

Note that this validator needs to have an empty constructor in order to be used with the annotation

Example

data class MyFormModel(

    @Hint("Value")
    @Validator<String>(EverySecondCharOneValidator::class)
    var value: String? = null,
)

...

Form<MyFormModel> {

    // Displays a Text field which is validated using EverySecondCharOneValidator
    FormTextField(MyFormModel::value)
}

Custom - Compose with factory

Sometimes it may be preferable to call composable code (for example to get a CompositionLocal or string resource) in a validator. For this reason, a @ComposeValidator annotation is provided which takes a ComposeValidatorFactory

Similar to @Validator the ComposeValidatorFactory must have a zero argument constructor.

By implementing the validator function of the ComposeValidatorFactory, a validator can be constructed in a composable context

Example

object NotEmptyWithComposableErrorFactory: ComposeValidatorFactory<String> {
    @Composable
    override fun validator(): CoreValidator<String> = NotEmptyValidator(
        stringResource(R.string.validator_not_empty)
    )
}

data class MyFormModel(

    @Hint("Value")
    @ComposeValidator<String>(NotEmptyWithComposableErrorFactory::class)
    var value: String? = null,
)

...

Form<MyFormModel> {

    // Displays a Text field which cannot be empty, and displays a string resource error
    FormTextField(MyFormModel::value)
}