Validations

In Rails, forms usually have an associated model object. Models define validations which include validation messages that describe which validations failed and why. Primer forms automatically display validation messages when a model object is provided.

Custom validation messages

All form inputs allow overriding the default validation message via the :validation_message argument:

class ExampleForm < ApplicationForm
  form do |example_form|
    example_form.text_field(
      name: :foo,
      label: "Foo",
      validation_message: "Custom validation message"
    )
  end
end

A custom validation message is also useful if no associated model object is available, i.e. for forms that are not tied to a database table.

Input focus

Primer forms will automatically focus the first invalid input in accordance with accessibility best-practices. Inputs are considered invalid if the associated model's field is invalid or if a custom validation message has been provided.