I''m trying to model a somewhat complicated genetic relationship in Rails. class Gene < ActiveRecord::Base belongs_to :species, :foreign_key => "species_id", :class_name => "Species" has_many :genes_orthogroups, :class_name => ''GenesOrthogroups'' # join table model has_many :orthogroups, :through => :genes_orthogroups has_many :orthologs, :through => :orthogroups, :source => :genes, :conditions => ''gene.species_id != ortholog.species_id'' end class GenesOrthogroups < ActiveRecord::Base belongs_to :gene belongs_to :orthogroup end class Orthogroup < ActiveRecord::Base has_many :genes_orthogroups, :class_name => ''GenesOrthogroups'' has_many :genes, :through => :genes_orthogroups belongs_to :species_pair, :class_name => ''SpeciesPair'', :foreign_key => "species_pair_id" end class SpeciesPair < ActiveRecord::Base belongs_to :species1, :foreign_key => "species1_id", :class_name => ''Species'' belongs_to :species2, :foreign_key => "species2_id", :class_name => ''Species'' has_many :orthogroups end class Species < ActiveRecord::Base has_many :genes has_many :species_pairs, :class_name => ''SpeciesPair'' end I''m trying to print out a list of the orthologs with a partial. The list is generated with: def find_ortholog_list(gene_id) ortholog_list = [] Gene.find(gene_id).orthologs.each do |ortholog| ortholog_list << ortholog end return OrthologList.new(ortholog_list) end I get the following error message: Invalid source reflection macro :has_many :through for has_many :orthologs, :through => :orthogroups. Use :source to specify the source reflection. If I change :source to :gene instead of :genes, I get: Could not find the source association(s) :gene in model Orthogroup. Try ''has_many :orthologs, :through => :orthogroups, :source => <name>''. Is it one of :genes_orthogroups, :genes, or :species_pair? Essentially, any given gene should have zero, one, or multiple orthologs in another species. These are grouped into orthogroups, each consisting of genes from two species, and representing a many-to-many relationship. Genes in an orthogroup which are of the same species would be paralogs instead. Because there are more than just two species, a gene may participate in multiple orthogroups (up to one for each additional species). The generalization for ortholog/paralog is "homolog" or "homologue," incidentally. I''ve based most of this code on the p.369 explanation "Using Models as Join Tables" in Agile Web Development with Rails (3rd Ed). I''m not really sure why it fails, except for the fact that I''m trying to use Gene as its own source for defining orthologs. What''s the proper way to define this relationship? Apologies for the complexity of the model. I couldn''t think of any layman''s examples. Thanks so much, John
The :orthologs association is the problem - Rails doesn''t support nesting :through associations. I recall there being a plugin around someplace to do it, so you may want to look into that. Depending on what you need, a simple instance method may work as well. For example (on Gene): def orthologs genes_orthogroups.ortholog_groups_for(self).map { |g| g.gene } end On GenesOrthogroup: named_scope ortholog_groups_for { |g| { :include => :gene, :conditions => [''genes.species_id != ?'', g.species_id] } } (not tested, but should be close to working) A couple general things: - model names should be singular (GenesOrthogroup rather than GenesOrthogroups). Otherwise you''ll eventually run into issues. - when writing SQL fragments in conditions, table names are plural (so genes.whatever rather than gene.whatever). - the association macros have sensible defaults, so you can leave some options out. For instance, the :species association in Gene can be simplified to ''belongs_to :species'' - Rails will find the correct FK (species_id) and class (Species). --Matt Jones On Jun 28, 8:07 pm, John Woods <john.wo...-+ksaPUZU+wsI+954vlgkHg@public.gmane.org> wrote:> has_many :genes_orthogroups, :class_name => ''GenesOrthogroups'' # > join table model > has_many :orthogroups, :through => :genes_orthogroups > has_many :orthologs, :through => :orthogroups, :source > => :genes, :conditions => ''gene.species_id != ortholog.species_id'' > end
The plural model name comes from the Agile Development book. They have an example--categories_products, linking categories to products--which they turn into a model. Should it be renamed category_product? Or is categories_product correct? I''m a bit confused about this, so thanks for bringing it up. I''ll look around for the plugin. Thanks so much, Matt! John On Jun 29, 10:46 am, Matt Jones <al2o...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:> The :orthologs association is the problem - Rails doesn''t support > nesting :through associations. I recall there being a plugin around > someplace to do it, so you may want to look into that. > > Depending on what you need, a simple instance method may work as well. > For example (on Gene): > > def orthologs > genes_orthogroups.ortholog_groups_for(self).map { |g| g.gene } > end > > On GenesOrthogroup: > named_scope ortholog_groups_for { |g| { :include => :gene, :conditions > => [''genes.species_id != ?'', g.species_id] } } > > (not tested, but should be close to working) > > A couple general things: > > - model names should be singular (GenesOrthogroup rather than > GenesOrthogroups). Otherwise you''ll eventually run into issues. > > - when writing SQL fragments in conditions, table names are plural (so > genes.whatever rather than gene.whatever). > > - the association macros have sensible defaults, so you can leave some > options out. For instance, the :species association in Gene can be > simplified to ''belongs_to :species'' - Rails will find the correct FK > (species_id) and class (Species). > > --Matt Jones > > On Jun 28, 8:07 pm, John Woods <john.wo...-+ksaPUZU+wsI+954vlgkHg@public.gmane.org> wrote: > > > has_many :genes_orthogroups, :class_name => ''GenesOrthogroups'' # > > join table model > > has_many :orthogroups, :through => :genes_orthogroups > > has_many :orthologs, :through => :orthogroups, :source > > => :genes, :conditions => ''gene.species_id != ortholog.species_id'' > > end
I''ll look at the rest of your example later, but... John Woods wrote:> The plural model name comes from the Agile Development book. They have > an example--categories_products, linking categories to products--which > they turn into a model. Should it be renamed category_product?[...] If I had to choose one of those options, I''d probably use CategoryProduct and rename the table. However, I think neither option is very good. What most people here seem to recommend is this: when your join table becomes a model, take the time to come up with an appropriate name for it. For example, in this case, we might go from Category habtm Products (with categories_products table) to class Category has_many :categorizations has_many :products, :through => :categorizations end (likewise for Product) class Categorization belongs_to :category belongs_to :product end Choosing an appropriate name for the join model will make future development much easier and clearer. Best, -- Marnen Laibow-Koser http://www.marnen.org marnen-sbuyVjPbboAdnm+yROfE0A@public.gmane.org -- Posted via http://www.ruby-forum.com/.
So the plugin appears to work. FYI, it''s here: git://github.com/ianwhite/nested_has_many_through.git Unfortunately, I''m still having trouble setting up the condition. I''ve renamed a few things and added appropriate associations: class Gene < ActiveRecord::Base belongs_to :species has_many :gene_orthogroup_linkers, :class_name => ''GeneOrthogroupLinker'' has_many :orthogroups, :through => :gene_orthogroup_linkers has_many :ortholog_orthogroup_linkers, :class_name => ''GeneOrthogroupLinker'', :through => :orthogroups, :source => :gene_orthogroup_linkers has_many :orthologs, :source => :gene, :through => :ortholog_orthogroup_linkers, :conditions => ''genes.species_id !genes_2.species_id'' end GeneOrthogroupLinker is the class that used to be GenesOrthogroups. Mysql::Error: Unknown column ''genes_2.species_id'' in ''where clause'': SELECT `genes`.* FROM `genes` INNER JOIN gene_orthogroup_linkers ON ( genes.id = gene_orthogroup_linkers.gene_id ) INNER JOIN orthogroups ON ( gene_orthogroup_linkers.orthogroup_id = orthogroups.id ) INNER JOIN gene_orthogroup_linkers gene_orthogroup_linkers_2 ON ( orthogroups.id = gene_orthogroup_linkers_2.orthogroup_id ) WHERE (gene_orthogroup_linkers_2.gene_id = 556 AND genes.species_id ! = genes_2.species_id) So, it looks to me like the problem is that it selects from genes but has no inner join to genes_2, only to gene_orthogroup_linkers_2. How do I get it to INNER JOIN genes genes_2 ON ( gene_orthogroup_linkers_2.gene_id = genes_2.id AND genes.species_id ! = genes_2.species_id)? It seems like as a work-around, I could add a species_id column on the GeneOrthogroupLinker model, but that doesn''t seem like the cleanest solution. Incidentally, it seems unnecessary to join with orthogroups (why not just join the two linkers with orthogroup_id?). Is this easily fixable, or better left as-is? I also tried the named_scope, but it doesn''t seem right for this situation. Best, John On Jun 29, 10:46 am, Matt Jones <al2o...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:> The :orthologs association is the problem - Rails doesn''t support > nesting :through associations. I recall there being a plugin around > someplace to do it, so you may want to look into that. > > Depending on what you need, a simple instance method may work as well. > For example (on Gene): > > def orthologs > genes_orthogroups.ortholog_groups_for(self).map { |g| g.gene } > end > > On GenesOrthogroup: > named_scope ortholog_groups_for { |g| { :include => :gene, :conditions > => [''genes.species_id != ?'', g.species_id] } } > > (not tested, but should be close to working) > > A couple general things: > > - model names should be singular (GenesOrthogroup rather than > GenesOrthogroups). Otherwise you''ll eventually run into issues. > > - when writing SQL fragments in conditions, table names are plural (so > genes.whatever rather than gene.whatever). > > - the association macros have sensible defaults, so you can leave some > options out. For instance, the :species association in Gene can be > simplified to ''belongs_to :species'' - Rails will find the correct FK > (species_id) and class (Species). > > --Matt Jones > > On Jun 28, 8:07 pm,JohnWoods<john.wo...-+ksaPUZU+wsI+954vlgkHg@public.gmane.org> wrote: > > > has_many :genes_orthogroups, :class_name => ''GenesOrthogroups'' # > > join table model > > has_many :orthogroups, :through => :genes_orthogroups > > has_many :orthologs, :through => :orthogroups, :source > > => :genes, :conditions => ''gene.species_id != ortholog.species_id'' > > end