$ show heartcombo/simple_form
Simple Form is a mature Ruby gem that provides a DSL for building HTML forms in Rails applications. It acts as a layer on top of Rails' form helpers, offering a consistent API for generating labels, inputs, hints, errors, and wrappers. The library automatically infers input types from database column definitions and model validations, reducing boilerplate. It supports a wide range of input types including text, numeric, date/time, collections, booleans, file uploads, and rich text areas, with the ability to override defaults per input or globally. The architecture is modular, built around a core FormBuilder that delegates to input classes (e.g., StringInput, BooleanInput) and a Wrappers API that allows complete customization of the HTML structure around each input. Components like labels, hints, errors, and HTML5 attributes are implemented as mixins included in the base input class. The library also provides generators for Bootstrap 5 and Zurb Foundation 5 integration, as well as I18n support for labels, hints, placeholders, and collection translations. Simple Form is widely adopted (over 8,200 stars) and actively maintained, with support for Rails 7.0 through 8.0 and Ruby 2.7+. Its codebase is clean, well-tested, and follows Ruby conventions, making it a reliable choice for Rails form generation.
The LLM identified 5 files worth highlighting for reuse:
Provides a DSL for defining form wrappers with `use`, `optional`, and `wrapper` methods. This is a clean implementation of the Builder pattern that allows developers to compose HTML structures declaratively. It is self-contained and could be extracted for other DSL-based HTML generation tasks.
A small module that extends classes with a `map_type` class method to register input type mappings. It uses `class_attribute` for inheritance-safe configuration. This pattern is reusable for any system that needs to map symbols to classes.
Contains CollectionRadioButtons and CollectionCheckBoxes classes that extend Rails' collection helpers with custom rendering logic (item wrappers, nested boolean style, label generation). The `CollectionExtensions` module encapsulates reusable collection rendering logic that could be applied to other collection-based form helpers.
The base class for all input types. It includes all component modules (Errors, Hints, HTML5, etc.) and provides the initialization logic for attribute name, column, input type, and options. The `merge_wrapper_options` method and `translate_from_namespace` I18n lookup are well-designed reusable utilities.
Implements error and full_error components with support for custom error messages, error methods (first, to_sentence), and association errors. The logic for determining if an object has errors and rendering them is cleanly separated and could be reused in other form-related contexts.