Undefined method `user_id' for nil:NilClass | Devise and Rails 4

In my application I want only current user to edit and delete his/her
stuff
and for others stuff he just able to show it. I’m using devise with
rails 4.

Here my files.

Migration

rails g migration AddUserIdToStudents user:references

user.rb

class User < ActiveRecord::Base
has_many :students
end

student.rb

class Student < ActiveRecord::Base
belongs_to :user
end

student_controller.rb

class StudentsController < ApplicationController
before_action :authenticate_user!
before_action :set_student, only: [:show, :edit, :update, :destroy]

def index
end

Branch wise students

def mechanical
@students = Student.where(Branch: “Mechanical Engineering”)
end
def infomation_technology
@students = Student.where(Branch: “Information Technology”)
end

def new
@student = current_user.students.build
end

def edit
end

def create
@student = current_user.students.build(student_params)

respond_to do |format|
  if @student.save
    format.html { redirect_to @student}
    format.json { render :show, status: :created, location: @student 

}
else
format.html { render :new }
format.json { render json: @student.errors, status:
:unprocessable_entity }
end
end
end

private
def set_student
@student = Student.find(params[:id])
end

def student_params
  params.require(:student).permit( :University_Roll_Number, :avatar,

:Department_Type, :user_id)
end
end

_actions.html.erb

<% @students.each do |student| %>

<div class="center-align">

  <!-- If Statement -->

  <% if current_user.try(:admin?) %>

    <%= link_to student, :class=> "btn waves-light waves-effect grey

darken-4" do %>

      <span class="button-name">Show</span>

    <% end %>

    <%= link_to edit_student_path(student), :class=> "btn 

waves-light
waves-effect grey darken-4" do %>

      <span class="button-name">Edit</span>

    <% end %>

    <%= link_to student, method: :delete, data: { confirm: 'Are you

sure?’ }, :class=> “btn waves-light waves-effect grey darken-4” do %>

      <span class="button-name">Delete</span>

    <% end %>

  <!-- Else If Statement -->

  <% elsif @student.user_id == current_user.id %>

    <%= link_to student, :class=> "btn waves-light waves-effect grey

darken-4" do %>

      <span class="button-name">Show</span>

    <% end %>

    <%= link_to edit_student_path(student), :class=> "btn 

waves-light
waves-effect grey darken-4" do %>

      <span class="button-name">Edit</span>

    <% end %>

    <%= link_to student, method: :delete, data: { confirm: 'Are you

sure?’ }, :class=> “btn waves-light waves-effect grey darken-4” do %>

      <span class="button-name">Delete</span>

    <% end %>

  <!-- Else Statement -->

  <% else %>

    <%= link_to student, :class=> "btn waves-light waves-effect grey

darken-4" do %>

      <span class="button-name">Show</span>

    <% end %>

  <% end %>

</div>
<% end %>

With all that configuration I’m getting following error undefined
method
`user_id’ for nil:NilClass. In my students table user_id is passing but
still facing this error. Where am I doing wrong.


Cheers!

Deepak Kumar Sharma
Guru Nanak Dev Engineering College
India!

Blog: http://deekysharma.wordpress.com

On 19 May 2016 at 18:52, Deepak S. [email protected] wrote:

In my application I want only current user to edit and delete his/her stuff
and for others stuff he just able to show it. I’m using devise with rails 4.

With all that configuration I’m getting following error undefined method
`user_id’ for nil:NilClass. In my students table user_id is passing but
still facing this error. Where am I doing wrong.

Initially what you are doing wrong is not posting the full error
message and not telling us which line of code the error refers to.
The error means that you have tried to call something.user_id but the
value of ‘something’ is nil. Look at the line of code the error
refers to and try to work out why the variable is nil.

Colin

On Fri, May 20, 2016 at 1:50 AM, Colin L. [email protected] wrote:

Initially what you are doing wrong is not posting the full error
message and not telling us which line of code the error refers to.
The error means that you have tried to call something.user_id but the
value of ‘something’ is nil. Look at the line of code the error
refers to and try to work out why the variable is nil.

I’m getting an error message because of following statement

<% elsif @student.user_id == current_user.id %>

<% end %>

@student.user_id not working. But in DB id’s are not empty and user_id
also
exists in student’s table.

If I go like this

<% @students.each do |student| %>
<% elsif student.user_id == current_user.id %>

<%end %>
<% end %>

Intially everything woks fine. Current user able to edit, delete and
show
his profile and other user’s able to show it only (i.e only show button
appear). Else and Elsif statements works fine. But when another user add
his data and after saving he’s able to edit and delete current user’
data.

Case 1: (Current user add his data)

Current User:

Show | Delete | Edit

Another User:

Show (Current User profile)

Case 2: (When another user enters his data and after saving it)

Current User:

Show | Edit | Delete

Another User:

Show | Edit | Delete (Current User profile)


Cheers!

Deepak Kumar Sharma
Guru Nanak Dev Engineering College
India!

Blog: http://deekysharma.wordpress.com

On 19 May 2016 at 21:58, Deepak S. [email protected] wrote:

I’m getting an error message because of following statement

<% elsif @student.user_id == current_user.id %>

<% end %>

@student.user_id not working. But in DB id’s are not empty and user_id also
exists in student’s table.

Note that here you have put @student.user_id

If I go like this

<% @students.each do |student| %>
<% elsif student.user_id == current_user.id %>

Also note that her you have said student.user_id (no ‘@’)
In the code you posted initially it is @student, which is nil as you
have not assigned a value to it.

Colin

On Fri, May 20, 2016 at 2:40 AM, Colin L. [email protected] wrote:

Note that here you have put @student.user_id

Also note that her you have said student.user_id (no ‘@’)
In the code you posted initially it is @student, which is nil as you
have not assigned a value to it.

Yes, I tried to different approach with @student I’m getting an error
of undefined ‘user_id’ and with student.user_id things work but in
abrupt manner.

And I figured out where I’m commit mistake.

Actually my index.html.erb has partial and that partial has sub-partial.

Index.html.erb
|–Partial File
|— Partial File

And in both partial files, in order to access data i’m passing each loop
i.e

<% @students.each do |student| %>
<% end %>

Now I deleted sub-partial and put all content in single partial file.

Index.html.erb
|— Partial File

Now everything working fine.


Cheers!

Deepak Kumar Sharma
Guru Nanak Dev Engineering College
India!

Blog: http://deekysharma.wordpress.com

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