Eager loading with find_by_sql

rubyonrails-talk
1

I have a model Tweets, it has_many :teams

I wrote a custom find_by_sql query for tweets (yes i tried all other approaches) such that I can't eager load the teams. I collect the ids and try to fake eager loading myself like so...

team_hash = {} #collect up the tweet ids tweet_ids = tweets.collect{|t| t.id}

#find the associated teams TeamTweet.find(:all, :include => :team, :conditions => "tweet_id IN (" + tweet_ids.join(',') +")").each do |tt|    team_hash[tt.tweet_id] = team_hash[tt.tweet_id] ? team_hash [tt.tweet_id] << tt.team : [tt.team] end

#reset the teams attribute tweets.each do |tweet|   teams = team_hash[tweet.id] ? team_hash[tweet.id] :   tweet.write_attribute(:teams, teams)   # also tried tweet.teams = teams end

I'm not sure f there is a better way to do this in general but when I access tweet.teams it still queries the database for the teams on each tweet even though I set it already. I assumed this would be a common problem for people using find_by_sql but can't find anything. Any solutions or suggestions would be greatly appreciated!

2

I have a model Tweets, it has_many :teams

I wrote a custom find_by_sql query for tweets (yes i tried all other approaches) such that I can't eager load the teams. I collect the ids and try to fake eager loading myself like so...

team_hash = {} #collect up the tweet ids tweet_ids = tweets.collect{|t| t.id}

#find the associated teams TeamTweet.find(:all, :include => :team, :conditions => "tweet_id IN (" + tweet_ids.join(',') +")").each do |tt| team_hash[tt.tweet_id] = team_hash[tt.tweet_id] ? team_hash [tt.tweet_id] << tt.team : [tt.team] end

#reset the teams attribute tweets.each do |tweet| teams = team_hash[tweet.id] ? team_hash[tweet.id] : tweet.write_attribute(:teams, teams) # also tried tweet.teams = teams end

Associations aren't attributes :slight_smile: There's a few bits of state you need to fake up to convince AR that it has loaded an association. The canonical example of this is probably the stuff in association_preload.rb in Rails itself.

Fred

3

I'd recommend that you take a look at the association_preload.rb code as well; I also wonder if the list might be able to help with the find_by_sql query, given that you're working too hard on the conditions below - :conditions => { :tweet_id => tweet_ids } will do the same thing you're spelling out explicitly.

--Matt Jones

4

Thanks for the tip on the :conditions use Matt. I ended up just doing

tweet.write_attribute(:eager_teams, teams)

I did this instead of trying to overwrite the association (which Frederick aptly pointed out was not an attribute) and access that property in the view instead of teams...its not the ideal solution but it will do until a better solution presents itself.

Thanks!