Validation and conversion

Validate the generated holder, then use the conversion method emitted for the form’s field contracts. Validation reports invalid editable values; conversion reconstructs the source model and can separately report a missing required value or a failed reverse conversion.

A non-optional shape-backed field can still start empty when its shape uses required storage and no default = ... is declared. Fallible holder conversion reports that missing value. When the form enables Koruma integration, generated validate() reports it too.

The derive emits the checked conversion method for any non-defaulted shape-policy component because the policy is resolved through the shape type. A direct-storage policy always supplies a value, so that checked conversion cannot fail at runtime unless another field has a fallible conversion.

Validate with Koruma

Koruma validation can run directly against form-side values:

use gpui_form::GpuiForm;
use koruma::Koruma;
use koruma_collection::{collection::NonEmptyValidation, numeric::RangeValidation};

#[derive(Clone, Debug, GpuiForm)]
#[gpui_form(koruma)]
struct Registration {
    #[gpui_form(component(gpui_form_collection::input::Input::<_>))]
    #[koruma(NonEmptyValidation::<_>)]
    username: String,

    #[gpui_form(component(gpui_form_collection::number_input::NumberInput::<_>))]
    #[koruma(RangeValidation::<_>.min(18).max(120))]
    age: u8,
}

GpuiForm copies the field validators to RegistrationFormValueHolder and derives its Koruma implementation. The Koruma import brings the validate() method into scope; the source model only needs its own Koruma derive when the application also validates that model directly. All configured validators run in attribute order:

let holder = RegistrationFormValueHolder::default();

if let Err(errors) = holder.validate() {
    if errors.username().non_empty_validation().is_some() {
        eprintln!("username must not be empty");
    }
}

Use #[gpui_form(koruma(fluent))] when the application has enabled the Koruma Fluent features and installed its application-owned localizer. The generated holder derives KorumaAllFluent and exposes localized failed-validator values through all(); the source model does not need that derive unless it is also validated directly.

Convert validated newtypes

For #[koruma(newtype)] source fields, use value(koruma_newtype) inside the field intent. The generated holder edits the inner value and reconstructs the validated wrapper through Koruma’s public newtype traits.

Call the fallible conversion method after validate(). Validation is still useful even when conversion is checked because it can expose field-specific validator errors instead of only the first reconstruction failure.

Troubleshooting