Question

This should be a very basic question, I’m still new to ruby so i’d appreciate some help.

So I have 3 tables in my db, Source, SourceType and Feed. Every Source belongs to a SourceType and Every Feed Belongs to a Source. Their primary keys are SourceID, TypeID and FeedID

my Active Record Classes are:

class SourceFeed < ActiveRecord::Base
  self.table_name = "SourceFeed"
  self.primary_key = "FeedID"

  belongs_to :Source, 
  :foreign_key => "SourceID", 
  :class_name => "Source",
  :include => "SourceType"
end

class Source < ActiveRecord::Base
  self.table_name = "Source"
  self.primary_key = "SourceID"

  has_many :SourceFeeds, 
  :primary_key => "SourceID", 
  :class_name => "SourceFeed"

  belongs_to :SourceType,
  :foreign_key => "TypeID", 
  :class_name => "SourceType"
end

class SourceType < ActiveRecord::Base
  self.table_name = "SourceType"
  self.primary_key = "TypeID"

  has_many :Source, 
  :primary_key => "TypeID", 
  :class_name => "Source"
end

I am trying to select stuff from SourceFeed, Stuff from Source and the SourceType. Here’s the query:

feed = SourceFeed.select("SourceFeed.FeedID, Source.Name as SourceName, SourceType.Name as SourceType").joins(:Source, :SourceType).where(:FeedID => FeedID).first

I am getting a Association named 'SourceType' was not found; perhaps you misspelled it? Error

If I remove it from the Joins, I get an Unknown column 'SourceType.Name' in 'field list' error.

What’s the right way to do it?

Thanks

PS: My database doesn’t follow active records naming conventions, but I can’t change that I am working with an existing DB.

Answer 1

Your query only works if there’s an association named “SourceType” defined in SourceFeed. You don’t have it, so you got the error.
I think this should work:

feed = SourceFeed.select("SourceFeed.FeedID, Source.Name as SourceName, SourceType.Name as SourceType").joins(:Source).joins("JOIN SourceType ON SourceType.TypeID = Source.TypeID").where(:FeedID => FeedID).first

UPDATE:
Definitely, Derek Harmel’s answer is a better one. SQL should be avoided whenever possible.