NoMethod Error undefined method `first_name' for nil:NilClass - ruby-on-rails

Question

Running
Rails 4.1.8 |
Ruby 2.1.5p273
I'm trying to display the current username for notes that are created from current user using:
<%= "#{note.user.first_name.capitalize} #{note.user.last_name.capitalize[0]}" %> in show.html.erb.
<% #notes.each do |note| %>
<tr>
<td>
<h4>
<%= "#{note.user.first_name.capitalize} #{note.user.last_name.capitalize[0]}" %>
</h4>
<p><%= note.created_at.strftime("%-m/%-d/%y") %></p>
</td>
<td>
<p><%= h(note.comment).gsub(/\n/, '<br/>').html_safe %></p>
If I take <%= "#{note.user.first_name.capitalize} #{note.user.last_name.capitalize[0]}" %> the app works just fine.
I also checked the NotesController for note as well and I can't seem to find the issue.
class NotesController < ApplicationController
before_action :set_note, only: [:edit, :update, :destroy]
before_action :set_account
before_action :authenticate_user!
before_action :check_user, only: [:edit, :update, :destroy]
# GET /notes/new
def new
#note = Note.new
end
# GET /notes/1/edit
def edit
end
# POST /notes
# POST /notes.json
def create
#note = Note.new(note_params)
#note.user_id = current_user.id
#note.account_id = #account.id
respond_to do |format|
if #note.save
format.html { redirect_to #account, notice: 'note was successfully created.' }
format.json { render :show, status: :created, location: #note }
else
format.html { render :new }
format.json { render json: #note.errors, status: :unprocessable_entity }
end
end
end
# PATCH/PUT /notes/1
# PATCH/PUT /notes/1.json
def update
respond_to do |format|
if #note.update(note_params)
format.html { redirect_to account_path(#account), notice: 'note was successfully updated.' }
format.json { render :show, status: :ok, location: #note }
else
format.html { render :edit }
format.json { render json: #note.errors, status: :unprocessable_entity }
end
end
end
# DELETE /notes/1
# DELETE /notes/1.json
def destroy
#note.destroy
respond_to do |format|
format.html { redirect_to account_path(#account), notice: 'note was successfully destroyed.' }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_note
#note = note.find(params[:id])
end
def set_account
#account = Account.find(params[:account_id])
end
def check_user
unless (#note.user == current_user) || (current_user.admin?)
redirect_to root_url, alert: "Sorry, this note belongs to someone else"
end
end
# Never trust parameters from the scary internet, only allow the white list through.
def note_params
params.require(:note).permit(:comment)
end
end
I'm sure it's something small I'm missing, I just can't see it.

Answer 1

You have a note that does not have a user associated with it, or one of the note users does not have first_name or a last_name (we would had known if you had posted the error message you are getting). If you want to guard against this, you have to make sure the user, first_name and last_name are not nil before calling methods on them:
In model:
def display_user_name
if user.nil?
"No user"
else
"#{user.first_name.present? ? user.first_name : '<missing>'} "\
"#{user.last_name.present? ? user.last_name.capitalize[0] : '<missing>'}"
end
end
In template:
<%= note.display_user_name %>
OR, you can use the great andand gem, then in your template you will have:
"#{note.user.andand.first_name.andand.capitalize} #{note.user.andand.last_name.andand.capitalize[0]}"
Just note that it will return " " (a string with a space in it) if the note has not user or has no first name and no last name.

Answer 2

Try this:
in Note class app/models/note.rb:
def user_name
#user_name ||= user.present? ? "#{user.first_name.capitalize} #{user.last_name.capitalize[0]}" : "No user" # or Anonymous(whichever suites your requirement)
end
then in your show.html.erb:
<%= note.user_name %>
Here:
You have one place to edit for any future references of user name in your application.
You do not repeat yourself(DRY) when you need to show user name of a note.
Easy to test.

Answer 3

I figured out the issue. I had serveral "notes" that had a few "null" values in the database which which is why it couldn't associated with the current_user.
After deleting those notes with null values, the problem was corrected.