Ruby on Rails each iteration error when one record

Question

I am stuck on what seems should have a very simple solution, but I can not find anything that will work! I am iterating results from a table on the index page (which returns a list of states). This works without any problems when multiple records are returned. However, when a single record is returned, I get an error: undefined method 'each' for #

I know it is causing the error when only one record is returned, but I can not find any documentation on how to handle this, especially in the case that 1 or 0 records could be returned.

Code in controller:

@states = State.find(params[:id])

Code in index page:

<ul>
  <% @states.each do |state| %>
    <li>
      <%= state.state_name %>
    </li>
  <% end %>
</ul>

Do you have multiple states with the same id?

Dave Newton
– Dave Newton

2015-01-22 15:30:40 +00:00
Commented Jan 22, 2015 at 15:30 — Dave Newton
– Dave Newton, Commented Jan 22, 2015 at 15:30

humza · Accepted Answer · 2015-01-22 15:35:05Z

4

Because you're using find, when you send multiple ids in the params, multiple records are matched; when you send a single id, a single instance is returned.

To ensure that each time, you get an ActiveRecord::Relation object that you can call each on, change your controller code to the following:

@states = State.where(id: params[:id]) # index action

You mentioned that it is the index view, so the above change should solve your problem.

If it's the show view, then you need to stick with find and change your view to display only one state.

edited Jan 22, 2015 at 15:35

answered Jan 22, 2015 at 15:29

humza

7,7643 gold badges21 silver badges29 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

user3461645 Over a year ago

Thank you! This worked perfectly, and was exactly what I was trying to do! I'm just starting to learn RoR and have only seen find being used in the tutorials. This helped a lot!

Noel Frostpaw · Accepted Answer · 2015-01-22 15:33:11Z

1

You need to check if it responds to .each, which is the prime given for knowing if something implements the enumerable module.

if @states.respond_to?(:each)
  # iteration goes here
else
  # single handling goes here

Ofcourse you can also use the .where option in your query which returns always a collection

@states = State.where(id: params[:id])

answered Jan 22, 2015 at 15:33

Noel Frostpaw

4,0096 gold badges32 silver badges54 bronze badges

Comments

Shamsul Haque · Accepted Answer · 2015-01-22 15:33:39Z

0

Scenario 1:-

When record is queried in controller as:

@states = State.find(params[:id])

Then in view it should be like that:

<p><%= @states.state_name %></p>

Scenario 2:-

When record is queried in controller as:

@states = State.all

Then in view it should be like that:

<ul>
  <% @states.each do |state| %>
    <li>
      <%= state.state_name %>
    </li>
  <% end %>
</ul>

Note:- In first scenario it is only one object but in second scenario it is a collection of object or a array of object. And only array are iterated.

answered Jan 22, 2015 at 15:33

Shamsul Haque

2,4512 gold badges19 silver badges20 bronze badges

Collectives™ on Stack Overflow

Ruby on Rails each iteration error when one record

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related