Rails Custom Form Builder

A good example/starter pack for a custom form builder for use with Rails form_for.

Aside from usage in normal Rails apps, custom form builders are also useful in creating Rails engines where customizing simple_form or another form gem dependency is not possible.

Currently the html classes/semantics are setup for Bootstrap 5, however it is designed to be generic and easy to modify to work with any CSS framework.

Installation

• Copy the CustomFormBuilder class to app/helpers/ or wherever else you like
• Copy the custom_form_for helper method to app/helpers/application_helper.rb
• Copy the views to app/views/form_builder/
• (Optional) Copy the Forms::Base class to app/lib/forms/ as it provides a very useful base class for forms that arent backed by an activerecord model. Provides required features for validations and some form_for requirements

Usage

<%= custom_form_for(@form, as: :my_form, url: request.path, defaults: {view_mode: false, input_html: {}}) do |f| %>
  <%= f.field :my_text, type: :text %>
  <%= f.field :my_num, type: :number %>
  <%= f.field :my_date, type: :date %>
  <%= f.field :my_datetime_local, type: "datetime-local" %>
  <%= f.field :my_time, type: :time %>
  <%= f.field :my_textarea, type: :textarea %>
  <%= f.field :my_checkbox, type: :checkbox %>

  <%= f.field :my_select, type: :select, collection: [], selected: [], disabled: [], prompt: "Select...", include_blank: false, input_html: {multiple: true} %>

  <%= f.view_field :my_readonly_field, label: "Foo", value: "bar" %>

  <%=
    ### Showing all field options
    f.field(
      :my_text,
      type: :text,
      value: "foo",
      name: "bar",
      field_wrapper_html: {},
      label_wrapper_html: {},
      label_html: {},
      input_wrapper_html: {},
      input_html: {},
      required: true,
      required_text: "*",
      field_layout: :horizontal,
      #field_layout: :vertical,
    )
  %>
<% end %>

Further documentation on custom form_for builders:

• https://www.brandnewbox.com/notes/2021/03/form-builders-in-ruby/
• https://api.rubyonrails.org/classes/ActionView/Helpers/FormBuilder.html

Credits

Created & Maintained by Weston Ganger - @westonganger