Rails can't create HABTM relationship

Question

I've got 2 models:

class Hashtag < ActiveRecord::Base
  has_and_belongs_to_many :photos
  attr_accessible :name
***
end

class Photo < ActiveRecord::Base
  has_and_belongs_to_many :hashtags, :uniq => true
***
end

Relationship create code:

photo = current_user.photos.new( params[:photo] )
if !photo.nil? and photo.save!
    photo.text.scan(/#[[:alnum:]]+/).each do |billet|
            next if billet.length > 25
            hashtag = Hashtag.first_or_initialize(:name => billet)
            if hashtag.persisted?
                hashtag.touch
            else
                hashtag.save!
            end
            photo.hashtags << hashtag
        end
    render json: photo
end

But it doesn't work. Looks like hashtags never be saved. What's wrong with this code?

UPD:

Join table:

def up
    create_table :hashtags_photos, :id => false do |t|
      t.integer :photo_id
      t.integer :hashtag_id
    end

    add_index :hashtags_photos, [:photo_id, :hashtag_id], :unique => true
  end

And error:

ActiveRecord::AssociationTypeMismatch: Hashtag(#70233360314580) expected, got TrueClass(#70233335523020)

What if you put `photo.hashtags << hashtag` above `if hashtag.persisted?`? — Brad Werth, Oct 19 '12 at 06:54
Do you have created a join table to realize the habtm relation? — davidb, Oct 19 '12 at 10:28

score 0 · Accepted Answer · answered Oct 20 '12 at 12:48

Right way to do it:

text.scan(/#[[:alnum:]]+/).each do |workpiece|
        next if workpiece.length > 25
        hashtag = Hashtag.find_by_name(workpiece)
        if hashtag
          hashtag.touch
        else
          hashtag = Hashtag.create!(:name => workpiece)
        end
        hashtags << hashtag
end

Rails can't create HABTM relationship

1 Answers1