Model.Save causing nil object error

rubyonrails-talk
1

Hello all.

Newbie to rails here and I am having a bit of an issue. I have the following models:

class Topic < ActiveRecord::Base   validates_presence_of :name   validates_length_of :name, :minimum => 3   has_many :relationship_topics   has_many :relationships, :through => :relationship_topics end

class Relationship < ActiveRecord::Base   has_many :relationship_topics   has_many :topics, :through => :relationship_topic end

class RelationshipTopic < ActiveRecord::Base   validates_uniqueness_of :topic, :scope => :relationship

  belongs_to :relationship   belongs_to :topic end

Now, here is example code of me trying to create a new RelationshipTopic:

@rel = RelationshipTopic.new(:relationship_id => 1, :topic_id => 1) => #<RelationshipTopic id: nil, relationship_id: 1, topic_id: 1, primary: nil, created_at: nil, updated_at: nil>

@rel.save

@rel.save NoMethodError: You have a nil object when you didn't expect it! The error occurred while evaluating nil.text?

Why am I unable to use the .save method when creating RelationshipTopics? Creating relationships and topics by itself works, but I can't get the join table to cooperate.

2

Hi Matthew Shapiro

      I think you are trying for uniq entry in join table(here relationship_topics).That you can do on db level In the migration file for this join table you can add after the creation of the table an index like

add_index :relationship_topics, [:relationship_id, :topic_id], :unique => true

    Then migrate as usual.Now the model save can be run inside a begin end block and rescue ActiveRecord::StatementInvalid error..You can also remove the line

validates_uniqueness_of :topic, :scope => :relationship     from above

Sijo