Rails 3 noob - difficulty populating an array

Question

UPDATED WITH SOLUTION FROM BELOW PRODUCES NEW ERROR.

Users invite others to review their work. To track this, the invitations table has reviewer_id and reviewee_id fields. The model contains:

belongs_to :user
has_many :users

To display all invitations for a user we first get all the invitations:

@invitations = Invitation.where("reviewee_id = ?", current_user.id ).select(:reviewer_id).order("updated_at")

Then we get all the users who were invited: (this part is wrong)

@reviewers = []
@invitations.each do |i|
  @reviewers << User.where("id = ?", i.reviewer_id )
end

This current solution produces the following:

undefined method `first_name' for []:ActiveRecord::Relation

I did a test with the following code to see what is in @reviewers:

<% @reviewers.each do |r| %>
   <%= r.id %><br>
<% end %>

Instead of returning the ids it returned:

2173491700
2173491200
2173490540

So the array is not getting populated appropriately.

I am grateful for your help and most grateful for specific code.

Douglas F Shearer · Accepted Answer · 2011-05-24 13:53:26Z

2

You want to gather up all the IDs then pass them to where.

reviewer_ids = @invitations.collect { |i| i.reviewer_id }
@reviewers = User.where(:id => reviewer_ids)

This grabs all the reviewers in a single database call.

answered May 24, 2011 at 12:36

Douglas F Shearer

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3 Comments

thanks! I am getting the following error, "Mysql2::Error: Operand should contain 1 column(s): SELECT users.* FROM users WHERE (id = 23,24,25)"

@Jay - You should do: @reviewers = User.where(:id => reviewer_ids)

No problem. Definitely go with what @mischa said re: where statement.

Raphael Petegrosso · Accepted Answer · 2011-05-24 12:35:15Z

1

Do the following to get the reviewers:

@reviewers = []
@invitations.each do |i|
  @reviewers << User.where("id = ?", i.reviewer_id )
end

The << adds elements to the array. And, before the iteration we create an array.

answered May 24, 2011 at 12:35

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thanks. I am using your solution. The error i am getting is now part of my post.