Efficient Form Customization and Validation with Rails

1. Simple Form <form action="/product/update" method="post"> Product: <input type="text" name="product"/><br /> Price: <input type="text" name="price" value="49.95"/><br /> <input type="submit" value="Submit"/> </form> CS 142 Lecture Notes: Forms

2. Rails Form Helpers Describes type, provides initial values <%= form_for(@user) do |form| %> <%= form.text_field(:name) %> <%= form.text_field(:login) %> <%= form.submit"Update User" %> <% end %> <form action="/site/users/2" method="post"> <input name="_method" type="hidden" value="put" /> <input id="user_login" name="user[login]“ size="30" type="text" value="pal" /> <input id="user_name" name="user[name]“ size="30" type="text" value="Philip Levis" /> <input name="commit" type="submit“ value="Update User" /> </form> Object representingform

3. Customize Format <%= form_for(@user) do |form| %> <table cellspacing="0" class="user_form"> <tr><td> <div class="user_field"> <%= f.label "Login*" %><br /> <%= f.text_field :login %> </div> <div class="user_field"> <%= f.label "Name*" %><br /> <%= f.text_field :name %> </div> <div class="action"> <%= form.submit "Update User" %> </div> </td></tr> </table> <% end %> CS 142 Lecture Notes: Forms

4. Post Action Method Hash with all of form data def update @user = User.find(params[:id]) @user.name = params[:user][:name] @user.login = params[:user][:login] if @user.save redirect_to@user, :notice => 'Success.' else render :action => :edit end end Redirects on success Redisplay form on error CS 142 Lecture Notes: Forms

5. More Compact Method Security checks in cause update to fail def update @user = User.find(params[:id]) if @user.update(params[:user]) redirect_to@user, :notice => 'Success.' else render :action => :edit end end CS 142 Lecture Notes: Forms

6. Rails 4 Pattern def update @user = User.find(params[:id]) if @user.update(user_params(params[:user])) redirect_to@user, :notice => 'Success. else render :action => :edit end end private def user_params(params) returnparams.permit(:name, :login) end Creates new hashcontaining onlyspecified elements CS 142 Lecture Notes: Forms

7. Creating New Record defcreate @user = User.new(user_params(params[:user])) if @user.save() then redirect_to(@user, :notice => "Success.") else render(:action => :new) end end CS 142 Lecture Notes: Forms

8. Validation (in Model) Built-in validator class User < ActiveRecord::Base validates :login, :presence => true, :uniqueness => true validates_format_of :login, :with => /[a-zA-Z0-9_-]+/, :message => "only letters, numbers, underscores (_), and dashes (-) are allowed" def validate_name if (name == "Kurt Cobain") then errors.add(:name, "Liar!") end end validate :validate_name end Custom validation method Saves error info CS 142 Lecture Notes: Forms

9. Error Messages <%= form_for(@user) do |form| %> <% if @user.errors.any? %> <div id="error_explanation"> <h2><%= pluralize(@user.errors.count, "error") %> prohibited this user from being saved:</h2> <ul> <% @user.errors.full_messages.each do |msg| %> <li><%= msg %></li> <% end %> </ul> </div> <% end %> <%= form.text_field(:name) %> <%= form.text_field(:login) %> <%= form.submit "Update User" %> <% end %> CS 142 Lecture Notes: Forms

10. File Uploads with Rails <%= form_for(@student) do |f| %> ... <%= f.file_field:input_file%> ... <% end %> In form post method: params[:user][:input_file].read() params[:user][:input_file].original_filename CS 142 Lecture Notes: Forms

11. CS 142 Lecture Notes: Cookies