CS 142 Lecture Notes: FormsSlide 1 Simple Form Product: Price:

Slide 2 Controller Code for Form class StudentsController < ApplicationController def index... end def edit if params[:id] = Student.find(params[:id]) = Student.new() end def update... end Display form Handle post

Slide 3 Rails Form Helpers <input id="student_name" name="student[name]“ size="30" type="text" value="Chen" /> <input id="student_birth" name="student[birth]“ size="30" type="text" value=" " /> <input name="commit" type="submit“ value="Modify Student" /> Describes type, provides initial values Object representing form

CS 142 Lecture Notes: FormsSlide 4 Customize Format...

CS 142 Lecture Notes: FormsSlide 5 Post Action Method def = Student.find(params[:id]) = = = = params[:student][:grad] then redirect_to(:action => :index) else render(:action => :edit) end Hash with all of form data Redirects on success Redisplay form on error

Security checks in Rails 4 cause update to fail CS 142 Lecture Notes: FormsSlide 6 More Compact Approach def = Student.find(params[:id]) then redirect_to(:action => :index) else render(:action => :edit) end

CS 142 Lecture Notes: FormsSlide 7 Rails 4 Pattern def = Student.find(params[:id]) params[:student])) then redirect_to(:action => :index) else render(:action => :edit) end private def student_params(params) return params.permit(:name, :birth, :gpa, :grad) end Creates new object where specified elements allowed for mass update

CS 142 Lecture Notes: FormsSlide 8 Creating New Record def = Student.new(student_params( params[:student]) then redirect_to(:action => :index) else render(:action => :edit) end

CS 142 Lecture Notes: FormsSlide 9 Validation (in Model) class Student < ActiveRecord::Base validates :birth, format: { with: /\d\d\d\d-\d\d-\d\d/, message: "must have format YYYY-MM-DD" } def validate_gpa if (gpa 4.0) then errors.add(:gpa, "must be between 0.0 and 4.0") end validate :validate_gpa end Custom validation method Built-in validator Saves error info

CS 142 Lecture Notes: FormsSlide 10 Error Messages :update, do |form| %>......

CS 142 Lecture Notes: FormsSlide 11 File Uploads with Rails In form post method: params[:student][:photo].read() params[:student][:photo].original_filename

CS 142 Lecture Notes: CookiesSlide 12