Ruby on Rails regarding updating a record

Question

When i want to update a student record, i am doing the patch request to the update action.But it is checking the student_id with NULL and not returning anything to update action.Any help would be greatly appreciated. Thanks in advance. Here are my routes.rb, students_controller.rb and edit.html.erb

routes.rb

root               'static_pages#home'
get 'student'   => 'students#home'
get 'addstudent'=> 'students#new'
get 'liststudent'=> 'students#index'
get 'updatestudent' => 'students#input'
get 'deletestudent' => 'students#inputDelete'

patch 'student' => 'students#update'
post '/search', to: 'students#edit', as: :search
post '/searchDelete', to: 'students#delete', as: :searchDelete  

students_controller.rb

class StudentsController < ApplicationController

    def home 
    end 

    def index
        @students = Student.all
    end

    def new
        @student = Student.new
    end

    def create 
        @student = Student.new(student_params)
        #render json: @student
        if @student.save
            flash[:success]="student added successfully"
            redirect_to new_student_path
        else 
            flash[:error]="Error while adding student"
            render "new"
        end
    end

    def input
    end

    def updateHome
        @student = Student.find_by(student_id: params[:q])
        render 'edit'        
    end

    def edit
        @student = Student.find_by(student_id: params[:q])
        #render json: @student
        render 'edit'
        #if @student.update_attributes(student_params)
        #   render json: @student
            #flash[:notice]="upate successful"
            #redirect_to "student_path"
        #else
        #   flash[:notice]="update not successful"
        #   redirect_to "student_path"
        #end
    end

    def update
    #   render text: "this is update action"
        @student = Student.find_by(id: params[:id])
        #@student.category = params[:category]
        #if @student
            render json: @student
        #end
    #   if @student.update_attributes(student_params)
    #       render json: @student
            #flash[:notice]="upate successful"
            #redirect_to "student_path"
    #   else
    #       render text: "went to else"
        #   flash[:notice]="update not successful"
        #   redirect_to "student_path"
    #   end
    end

    def inputDelete
    end

    def delete
        @student = Student.find_by(student_id: params[:q])
        #render json: @student
        #render text: "This is delete action"
        @student.destroy
        #Student.find_by(student_id: params[:q]).destroy
        flash[:success]="student delete successfully"
        redirect_to "student_path"
    end

    def student_params
        params.require(:student).permit(:firstname, :lastname, :student_id, :category, :gender, :phone, :dob, :program_id)  
    end
end

edit.html.erb

<h1>Update student profile</h1>

<% flash.each do |key, value| %>
    <div class="alert alert-<%= key %>"><%= value %></div>
 <% end %>
<div class="row">
 <div class="col-md-6 col-md-offset-3">
 <%= form_for @student do |f| %>

  <%= f.label :RecordId %>
  <%= f.text_field :id, class: 'form-control'  %>

  <%= f.label :FirstName %>
  <%= f.text_field :firstname, class: 'form-control'  %>

  <%= f.label :LastName %>
  <%= f.text_field :lastname, class: 'form-control' %>

  <%= f.label :Student_Id %>
  <%= f.text_field :student_id, class: 'form-control' %>

  <%= f.label :Category %>
  <%= f.text_field :category, class: 'form-control'  %>

  <%= f.label :Gender %>
  <%= f.text_field :gender, class: 'form-control' %>

  <%= f.label :PhoneNumber %>
  <%= f.text_field :phone, class: 'form-control' %>

  <%= f.label :DateOfBirth %>
  <%= f.text_field :dob, class: 'form-control'  %>

  <%= f.label :Program_Id %>
  <%= f.text_field :program_id, class: 'form-control' %>

  <%= f.submit "Save changes", class: "btn btn-primary" %>
<% end %>


  </div>
</div>

Log

Started PATCH "/student.5" for 127.0.0.1 at 2016-04-30 00:27:35 +0530
Processing by StudentsController#update as 
Parameters: {"utf8"=>"✓",                           "authenticity_token"=>"GlI8TPiB5Ua5XWH3Hwu3ycuhdaCFxST8rLQIuyJ
  7AlXGXeAQWN0IcD/iS04lXBhliMCSWvyYif4X5TMHupwDrg==", "student"=>     {"id"=>"5",        "firstname"=>"Rakesh", "lastname"=>"ALLAM", "student_id"=>"cs13b1002", "category"=>"obc", "gender"=>"Male", "phone"=>"8790352136", "dob"=>"1995-09-26", "program_id"=>"btech"}, "commit"=>"Save changes"}
  Student Load (0.6ms)  SELECT  "students".* FROM "students" WHERE "students"."id" IS NULL LIMIT 1
Completed 200 OK in 3ms (Views: 0.3ms | ActiveRecord: 0.6ms)

Answer 1

Based on your logs, it seems your 'id' is nested within 'student'

"student"=> {"id"=>"5", "firstname" => "Raskesh", ....}

Therefore, in your update action you should try

@student = Student.find_by(id: params[:student][:id])

or better yet...

@student = Student.find(params[:student][:id])

Answer 2

You have a problem with your URL:

/student.5

It should be:

/student/5

User Rails conventions and make your life easier. For example, use resources :students in your routes or use .find(:id) instead of .find_by(id: X), etc.

You can resolve this problem by specifying form action url yourself:

<%= form_for(@student, :url => url_for(:controller => 'students', :action => 'update', params: {id: @student.id})) do |f| %>

But, I would suggest resolving this problem by correctly setting up your routes by convention. This problem will be resolved automatically:

# routes.rb
resources :students

# edit.html.erb
<%= form_for @student do |f| %>