Question

This is probably something very simple but I m looking for the optimal way of retrieving all Products by Tag, so to speak. This is with Spree, so I should stick to the way they have modeled their data. It s actually Product and Taxon (like category, brand, etc.)

So if Product has_and_belongs_to_many :taxons and Taxon has_and_belongs_to_many :products, what s the best way to find all products by a Taxon?

Something like:

@taxon = Taxon.find_by_permalink( categories/ )
@products = Product.find_by_taxon(@taxon)

... but I m not sure what goes into that last method (just made up the name).

Answer 1

Probably you re going to just simply say if there s only one Taxon

@products = @taxon.products

If there s multiple we require a slightly different method. But even then you could just

@products = @taxons.inject([]) {|taxon| taxon.products}

Answer 2

@taxon = Taxon.find_by_permalink( categories , :include => :products)

This will eager-load the products so you can access them through

@taxon.products

without it hitting the database again. This is the more efficient form of just using .products that avoids N+1 query problems.

Answer 3

Won t Taxon.find_by_permalink( categories/ ).products suffice?

EDIT: Oh and for multiple taxons you could try something like this:

Product.find(:all, :include => :products_taxons, :conditions => { :products_taxons => {:taxon_id => [1,2,3]} }) # will find products with taxons with id 1, 2 or 3

Answer 4

I was able to get this working in Spree 2.1.0.beta with the following customizations:

Based on the answer here: Finding records with two specific records in another table

I added a new product scope in /app/models/spree/product_decorator.rb

Spree::Product.class_eval do
  add_search_scope :in_all_taxons do |*taxons|
    taxons = get_taxons(taxons)
    id = arel_table[:id]
    joins(:taxons).where(spree_taxons: { id: taxons }).group(id).having(id.count.eq(taxons.size))
  end
end

Then used the new scope by adding it to /app/models/spree/base_decorator.rb

Spree::Core::Search::Base.class_eval do
    def get_base_scope
      base_scope = Spree::Product.active
      base_scope = base_scope.in_all_taxons(taxon) unless taxon.blank?
      base_scope = get_products_conditions_for(base_scope, keywords)
      base_scope = add_search_scopes(base_scope)
      base_scope
    end
end

Now I can use the standard search helper to retrieve products (which means I can still supply keywords, etc along with the multiple taxons):

# taxon_ids is an array of taxon ids
@searcher = build_searcher(params.merge(:taxon => taxon_ids))
@products = @searcher.retrieve_products

This works for me and felt pretty painless. However, I m open to better options.

Answer 5

If you want to find a product by its tags you can use tagged_with

Example

Spree::Product.tagged_with("example")

Will return the products with the tag "example"

Source: https://github.com/mbleigh/acts-as-taggable-on

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