CODEWITHSUNDEEP
ruby-on-rails
4thSpace
4thSpace

Reputation: 44310

How to query on something other than id?

I have a model with these fields:

Department:
name:string
deptid:integer

I've run rake db:migrate and have seeded the table with 5 records. In the departments controller, I have:

def show
  @dept = Department.find(params[:deptid])
end

In show.html.erb:

<%= @dept.name %>

In routes.rb

get 'departments/:deptid' => 'departments#show'

When I do this localhost:3000/show/2, I get the second record. If I instead use localhost:3000/show/212, where deptid=212 is valid, I get a

Couldn't find Department with 'id' = 212

error. Since I have specified deptid and not id (primary key), why does it still look for the PK?

Upvotes: 2

Views: 53

Answers (1)

sevenseacat
sevenseacat

Reputation: 25029

The find method will always look up a record by its primary key - in this case, you have not changed the primary key, so it is trying to look up records by id.

If you want to look up a single record by a different field, you can use find_by (or find_by!, the difference being that find_by! will raise an exception if no record is found, just like find does). In this case, you probably want:

Department.find_by!(deptid: params[:deptid])

Upvotes: 3

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