Gracefully jumping to next record - ActiveRecord - ruby-on-rails

Rails 3.2
I have the following in my view:
<% #organizations.each do |o| %>
<% organization = Organization.find(o.organization_id) %>
<% if organization == nil %>
<% next %>
<% end %>
<tr>
<td><%= o.org_name %></td>
<td><%= number_to_currency(o.revenue, :precision => 0) %></td>
<td><%= o.rank %></td>
</tr>
<% end %>
I was under the impression that if organization is not found, execution would jump to the next record. Instead, I am getting the "something went wrong".
Looking through the log file, one of the organization_id is not found in the organizations table, and that's what's triggering the error.
Why isn't execution jumping to the next record?
Temporary Solution: I changed
<% organization = Organization.find(o.organization_id) %>
To:
<% organization = Organization.find_by_id(o.organization_id) %>
and that gives me a nil when it does not find anything. If it's nil, the execution skips to the next record

According to http://api.rubyonrails.org/classes/ActiveRecord/FinderMethods.html#method-i-find, Organization.find(o.organization_id) will raise an ActiveRecord::RecordNotFound for the id that does not exist in the table.
Addendum:
Try something like the following:
<% ids = #organizations.map(&:organization_id) %>
<% organizations = Organization.where(id: ids) %>
<% organizations.each do |o| %>
<tr>
<td><%= o.org_name %></td>
<td><%= number_to_currency(o.revenue, :precision => 0) %></td>
<td><%= o.rank %></td>
</tr>
<% end %>
With this method, you'll fetch all the organizations with 1 query from the DB as opposed to 1 for every organization.

Related

Create/New DB record for each generated set of fields

I have got a problem with saving multiple record.
This script wil load a list of instruments that belong to a department through a join table.
This form will make a new record for another join table, the problem is when I'f got 4 instruments it only will save the last instrument.
Image generated list
Can anybody help me out to solve this problem or point me into the right direction ??
<%= form_for(:joindaylisting) do |j| %>
<% #instrumentslist.each do |instrument| %>
<tr class="<%= cycle('odd', 'even') %>">
<td>
<% j.label(:instrument_id, "#{instrument.name}") %>
<%= link_to("#{instrument.name}", {:controller => 'instruments', :action => 'show_instruction', :instrument_id => instrument.id}, :onclick=>"window.open('height=670, width=675');return false;") %>
</td>
<%= j.hidden_field(:instrument_id, :value => instrument.id) %>
<td></td>
<% j.label(:ammountdesinfection, "") %>
<td><%= j.text_field(:ammountdesinfection) %></td>
<% j.label(:ammountinstruments, "") %>
<td><%= j.text_field(:ammountinstruments) %></td>
<% j.label(:ammountrelease, "") %>
<td><%= j.text_field(:ammountrelease) %></td>
<% j.label(:notes, "") %>
<td><%= j.text_area(:notes) %></td>
</tr>
<% j.label(:department_id) %>
<%= j.hidden_field(:department_id, :value => #department.id) %>
<% end %>
<% end %>
Only the last one is saved because the fields have the same name and the last one overrides all other values. See the params you are getting on the receiving controller.
You probably want/need to configure departments to accepts_nested_attributes_for :instruments and a form for the department object with fields_for: instruments. I've highlighted keywords that my help you get the information you want, the Rails Guides is a good place to start.

Show attribute value using its id

In my application, I am grouping my objects by an ID. At the moment, I can only display the ID, but I would like to display the attribute value.
A Fixture belongs_to a tournament and a tournament has_many fixtures.
Controller
def index
#fixtures = Fixture.all
#tournament_fixture = #fixtures.group_by {|f| f.tournament_id}
end
View
<% #tournament_fixture.sort.each do |tourn_name, fixture| %>
<%= tourn_name %>
<% fixture.each do |f| %>
<td><%= f.home_team %></td>
<td><%= f.away_team %></td>
<td><%= f.kickoff_time %></td>
</tr>
<% end %>
<% end %>
How can I get
<%= tourn_name %>
to display its corresponding value that is in its :name column?
At the moment in my view for example i get this returned
<tbody>
2
<tr>
<td>Tournament Name</td>
<td>Team 1</td>
<td>Team 2</td>
<td>2000-01-01 14:00:00 UTC</td>
<td><a class="btn btn-success" href="/fixtures/1">view</a></td>
</tr>
</tbody>
The 2 needs to be the value in the :name column
I'd recommend grouping by tournament instead:
#tournament_fixture = #fixtures.group_by(&:tournament)
And then iterate using:
<% #tournament_fixture.sort.each do |tournament, fixture| %>
<%= tournament.name %>
...
<% end %>
You can access the whole object much like you can get the id like this:
def index
#fixtures = Fixture.includes(:tournaments).all
#tournament_fixture = #fixtures.group_by {|f| f.tournament.name}
end
The id is still available as either f.tournament_id or f.tournament.id, should you still need it but I just figured you'd rather group by its name directly. I simply added an includes statement to also load the referenced Tournament objects with your fixtures in one go. Otherwise, Rails would load the tournaments only when you access them one by one.
As an alternative, you could load the Tournaments, including all their the fixtures instead and iterate over the tournaments like this:
Controller
def index
#tournaments = Tournament.includes(:fixtures).all
end
View
<% #tournaments.each do |tournament| %>
<%= tournament.name %>
<% tournament.fixtures.each do |f| %>
<td><%= f.home_team %></td>
<td><%= f.away_team %></td>
<td><%= f.kickoff_time %></td>
</tr>
<% end %>
<% end %>
It seems a bit more natural to me and you don't need to iterate over all fixtures to map them by their tournament.
You can load the fixtures in the right order. There is no need to group then in memory. Remember to include the tournaments to avoid N+1 queries.
# controller
def index
#fixtures = Fixture.order(:tournament_id).includes(:tournaments).all
end
Loading in the right order in the controller makes the view simpler. For the tournament's name just use the association between Fixture and Tournament.
# view
<% #fixtures.each do |fixture| %>
<tr>
<td><%= fixture.tournament.name %></td>
<td><%= fixture.home_team %></td>
<td><%= fixture.away_team %></td>
<td><%= fixture.kickoff_time %></td>
</tr>
<% end %>

serial number with pagination rails

I am using pagination for my index page where I list all the users information like name, email etc. In the table I want to display the serial number in the order [1,2,3...]. If I user the user_id and if I delete the user the number will be missing out of sequence. I use the following code in my view
<% #user.each_with_index do |d, i| %>
<tr>
<td><%= i+1 %></td>
<% if d.profile.present? %>
<td><%= link_to d.profile.first_name+ " "+d.profile.last_name, posts_individualpostlink_path(:id => d.id) %> </td>
<% else %>
<td><%= "No Profile" %></td>
<% end %>
<td><%= d.email %></td>
<% if d.profile.present? %>
<td><%= d.profile.date_of_birth %> </td>
<% else %>
<td><%= "No Profile" %></td>
<% end %>
</tr>
<% end %>
</table>
<%= will_paginate #user %>
when I am going to the second page again the serial number starts with [1,2,....]. Per Page if i am giving 10 users, the second page should show [11, 12, 13,..... in the table.
Can anyone help me to do this. Thanks
Try with
<%
count = ((params[:page] || 1).to_i - 1) * 10
#user.each_with_index do |d, i| %>
<tr>
<td><%= count + i %></td>
Before answering question, small emotional note: stop using single letter variables in Your code. It makes it completely unreadable.
Why not use <% #user.each_with_index do |user, idx| %> ? Now in You code block it's easy to understand that You always refer to user.
Now the answer. Will paginate add page parameter to the paging links. So in You controller You should be able to do this:
#page = params[:page] || 1
After that use it to calculate correct number in Your view:
<td><%= (#page - 1) * number_of_items_on_page + i+1 %></td>

undefined method `ncbi_ref_seq' for #<ActiveRecord::Associations::CollectionProxy []>

Generator has_many:results
Result belongs_to:generator
I want to have a page whereby i can view all the generators and the results.
For example :This is from my generator/index.html
this is from result/index.html
what i want to have is to combine them together and view all the data.
right now this is what i've changed but i get the error message undefined method for ncbi_ref_seq. ( ncbi_ref_seq is an attribute belonging to the class Result )
GeneratorController.rb
def index
#generators = Generator.all(:include => [:results])
end
Generator/index.html.erb
<tbody>
<% #generators.each do |generator| %>
<tr>
<td><%= generator.primer_length %></td>
<td><%= generator.choice %></td>
<td><%= generator.random_primer_generated %></td>
<td><%= generator.c_primer %></td>
<td><%= generator.results.ncbi_ref_seq %></td>
</tr>
<% end %>
Since a generator has many results. When you take generator.results it returns an Active Record Collection, so there would be several records of Results, so you can't just extra a ncbi_ref_seq.
Either you have to loop through generator.results and output each ncbi_ref_seq like so
<% for result in generator.results %>
<%= result.ncbi_ref_seq %>
<% end %>
Or a generator has_one result.

Rails undefined method `hospital' for nil:NilClass

Respected ppl ...
In my application i want to display the last hospital name for a given employee ...
for which i tried this :
<%= #employee.postings.last.hospital.hospital_name %>
All the required associations are correct ...as this works perfectly for all the employees who have a posting ... but i get the error for the employees who dont have even a single posting ...
I tried doing
<%= #employee.postings.last.hospital.hospital_name.to_s %>
and even
<% if !#employee.postings.last.hospital.nil? %>
and even a "try" function ....
I just want it to not display any data when there dosent exist one ... instead of the intimidating error ...
if i could just learn how to skip over printing nil values then it would be awesome ..as i am facing similar issues elsewhere too ...
For ex :
in my employees main page i want to display all the qualifications for each employee for which im doing :
<tbody>
<% #employees.each do |employee| %>
<tr>
<td><%= employee.emp_id %></td>
<td><%= employee.emp_treasury_id %></td>
<td><%= link_to employee.emp_full_name,employee_path(employee) %></td>
<% #employee.qualifications.each do |qualification| %>
<td><%= qualification.qualification_name.Qualification_name %></td>
<% end %>
</tr>
<% end %>
but i end up getting "undefined method `qualifications' for nil:NilClass" error once again ...
Im trying a lot ... but still ...
Thanx and Sincere Regards
-Sky
Try this
<%= #employee.postings.last.try(:hospital).try(:hospital_name) || "N/A" %>
using try
<%= #employee.postings.last.try(:hospital).try(:hospital_name) %>
using if
<%= #employee.postings.last.hospital.hospital_name if #employee.postings.exists? && #employee.positings.last.hospital %>
It should be
employee not #employee
Rest you use try or respond_to for being more safe. As you might not have run the migrations.
.respond_to?(:field) && model.try(:field)
Thanks
<% #employees.each do |employee| %>
<tr>
<td><%= employee.emp_id %></td>
<td><%= employee.emp_treasury_id %></td>
<td><%= link_to employee.emp_full_name,employee_path(employee) %></td>
<% employee.qualifications.each do |qualification| %>
<td><%= qualification.try(:qualification_name).try(:Qualification_name) %></td>
<% end %>
</tr>
<% end %>

Resources