Rails Form Helpers and Controller Code for Customizing Student Data
Explore how to use Rails form helpers, controller code, and customize formats to modify student data efficiently. Learn about handling form submissions, updating student information, and optimizing code for a more streamlined user experience in Rails applications.
Download Presentation
Please find below an Image/Link to download the presentation.
The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author. If you encounter any issues during the download, it is possible that the publisher has removed the file from their server.
You are allowed to download the files provided on this website for personal or commercial use, subject to the condition that they are used lawfully. All files are the property of their respective owners.
The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author.
E N D
Presentation Transcript
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 Slide 1
Controller Code for Form class StudentsController < ApplicationController def index ... end def edit if params[:id] then @student = Student.find(params[:id]) else @student = Student.new() end end Display form def update ... end end Handle post Slide 2
Rails Form Helpers Describes type, provides initial values <%= form_for(@student, method: :post, url: {action: :update, id: @student.id}) do |form| %> <%= form.text_field(:name) %> <%= form.text_field(:birth) %> <%= form.submit "Modify Student" %> <% end %> Object representing form <form action="/student/update/4" method="post"> <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="1990-02-04" /> <input name="commit" type="submit value="Modify Student" /> </form> Slide 3
Customize Format <%= form_for(@student, method: :post, url: {action: :update, id: @student.id}) do |form| %> <table class="form"> <tr> <td><%= form.label(:name, "Name:")%></td> <td><%= form.text_field(:name) %></td> </tr> <tr> <td><%= form.label(:birth, "Date of birth:")%></td> <td><%= form.text_field(:birth) %></td> </tr> ... <table> <%= form.submit "Modify Student" %> <% end %> CS 142 Lecture Notes: Forms Slide 4
Post Action Method Hash with all of form data def update @student = Student.find(params[:id]) ]) @student.name = params[:student][:name] @student.birth = params[:student][:birth] @student.gpa = params[:student][:gpa] @student.grad = params[:student][:grad] if @student.save then redirect_to(:action => :index) else render(:action => :edit) end end Redirects on success Redisplay form on error CS 142 Lecture Notes: Forms Slide 5
More Compact Approach def update @student = Student.find(params[:id]) if @student.update(params[:student]) then redirect_to(:action => :index) else render(:action => :edit) end end Security checks in Rails 4 cause update to fail CS 142 Lecture Notes: Forms Slide 6
Rails 4 Pattern def update @student = Student.find(params[:id]) if @student.update(student_params( params[:student])) then redirect_to(:action => :index) else render(:action => :edit) end end Creates new object where specified elements allowed for mass update private def student_params(params) return params.permit(:name, :birth, :gpa, :grad) end CS 142 Lecture Notes: Forms Slide 7
Creating New Record def create @student = Student.new(student_params( params[:student]) if @student.save() then redirect_to(:action => :index) else render(:action => :edit) end end CS 142 Lecture Notes: Forms Slide 8
Validation (in Model) Built-in validator class Student < ActiveRecord::Base validates :birth, format: { with: /\d\d\d\d-\d\d-\d\d/, message: "must have format YYYY-MM-DD" } Custom validation method def validate_gpa if (gpa < 0) || (gpa > 4.0) then errors.add(:gpa, "must be between 0.0 and 4.0") end end Saves error info validate :validate_gpa end CS 142 Lecture Notes: Forms Slide 9
Error Messages <% @student.errors.full_messages.each do |msg| %> <p><%= msg %></p> <% end %> <%= form_for(@student, method: :post, url: {action => :update, id: @student.id}) do |form| %> ... <%= form.label(:birth, "Date of birth:")%> <%= form.text_field(:birth) %> ... <% end %> CS 142 Lecture Notes: Forms Slide 10
File Uploads with Rails <%= form_for(:student, method: ...) do |form| %> ... <%= form.file_field(:photo) %> ... <% end %> In form post method: params[:student][:photo].read() params[:student][:photo].original_filename CS 142 Lecture Notes: Forms Slide 11
CS 142 Lecture Notes: Cookies Slide 12
