ClassProxy provides class-level methods on a dynamically chosen database.

Examples:

  db = CouchRest::Database.new(...)
  articles = Article.on(db)

  articles.all { ... }
  articles.by_title { ... }

  u = articles.get("someid")

  u = articles.new(:title => "I like plankton")
  u.save    # saved on the correct database

lib/couchrest/mixins/class_proxy.rb

@@ -0,0 +1,108 @@
+module CouchRest
+  module Mixins
+    module ClassProxy
+      
+      def self.included(base)
+        base.extend(ClassMethods)
+      end
+      
+      module ClassMethods
+
+        # Return a proxy object which represents a model class on a
+        # chosen database instance. This allows you to DRY operations
+        # where a database is chosen dynamically.
+        #  
+        # ==== Example:
+        #  
+        #   db = CouchRest::Database.new(...)
+        #   articles = Article.on(db)
+        #
+        #   articles.all { ... }
+        #   articles.by_title { ... }
+        #
+        #   u = articles.get("someid")
+        #
+        #   u = articles.new(:title => "I like plankton")
+        #   u.save    # saved on the correct database
+
+        def on(database)
+          Proxy.new(self, database)
+        end
+      end
+
+      class Proxy #:nodoc:
+        def initialize(klass, database)
+          @klass = klass
+          @database = database
+        end
+        
+        # ExtendedDocument
+        
+        def new(*args)
+          doc = @klass.new(*args)
+          doc.database = @database
+          doc
+        end
+        
+        def method_missing(m, *args, &block)
+          if has_view?(m)
+            query = args.shift || {}
+            view(m, query, *args, &block)
+          else
+            super
+          end
+        end
+        
+        # Mixins::DocumentQueries
+        
+        def all(opts = {}, &block)
+          @klass.all({:database => @database}.merge(opts), &block)
+        end
+        
+        def first(opts = {})
+          @klass.first({:database => @database}.merge(opts))
+        end
+        
+        def get(id)
+          @klass.get(id, @database)
+        end
+        
+        # Mixins::Views
+        
+        def has_view?(view)
+          @klass.has_view?(view)
+        end
+        
+        def view(name, query={}, &block)
+          @klass.view(name, {:database => @database}.merge(query), &block)
+        end
+        
+        def all_design_doc_versions
+          @klass.all_design_doc_versions(@database)
+        end
+        
+        def cleanup_design_docs!
+          @klass.cleanup_design_docs!(@database)
+        end
+        
+        # Mixins::DesignDoc
+        
+        def design_doc
+          @klass.design_doc
+        end
+        
+        def design_doc_fresh
+          @klass.design_doc_fresh
+        end
+        
+        def refresh_design_doc
+          @klass.refresh_design_doc
+        end
+        
+        def save_design_doc
+          @klass.save_design_doc_on(@database)
+        end
+      end
+    end
+  end
+end

lib/couchrest/mixins/extended_document_mixins.rb

@@ -4,3 +4,4 @@ require File.join(File.dirname(__FILE__), 'views')
 require File.join(File.dirname(__FILE__), 'design_doc')
 require File.join(File.dirname(__FILE__), 'validation')
 require File.join(File.dirname(__FILE__), 'extended_attachments')
+require File.join(File.dirname(__FILE__), 'class_proxy')

lib/couchrest/more/extended_document.rb

@@ -11,6 +11,7 @@ module CouchRest
     include CouchRest::Mixins::Views
     include CouchRest::Mixins::DesignDoc
     include CouchRest::Mixins::ExtendedAttachments
+    include CouchRest::Mixins::ClassProxy
     
     def self.inherited(subklass)
       subklass.send(:include, CouchRest::Mixins::Properties)

spec/couchrest/more/extended_doc_view_spec.rb

@@ -8,6 +8,7 @@ describe "ExtendedDocument views" do
     # Note: no use_database here
     property :title
     property :questions
+    property :professor
     view_by :title
   end
   
@@ -158,6 +159,13 @@ describe "ExtendedDocument views" do
       end
       things[0]["doc"]["title"].should =='aaa'
     end
+    it "should yield with by_key method" do
+      things = []
+      Unattached.by_title(:database=>@db) do |thing|
+        things << thing
+      end
+      things[0]["doc"]["title"].should =='aaa'
+    end
     it "should barf on get if no database given" do
       lambda{Unattached.get("aaa")}.should raise_error
     end
@@ -186,6 +194,67 @@ describe "ExtendedDocument views" do
     end
   end
 
+  describe "class proxy" do
+    before(:all) do
+      reset_test_db!
+      @us = Unattached.on(TEST_SERVER.default_database)
+      %w{aaa bbb ddd eee}.each do |title|
+        u = @us.new(:title => title)
+        u.save
+        @first_id ||= u.id
+      end
+    end
+    it "should query all" do
+      rs = @us.all
+      rs.length.should == 4
+    end
+    it "should make the design doc upon first query" do
+      @us.by_title
+      doc = @us.design_doc
+      doc['views']['all']['map'].should include('Unattached')
+    end
+    it "should merge query params" do
+      rs = @us.by_title :startkey=>"bbb", :endkey=>"eee"
+      rs.length.should == 3
+    end
+    it "should query via view" do
+      view = @us.view :by_title
+      designed = @us.by_title
+      view.should == designed
+    end
+    it "should yield" do
+      things = []
+      @us.view(:by_title) do |thing|
+        things << thing
+      end
+      things[0]["doc"]["title"].should =='aaa'
+    end
+    it "should yield with by_key method" do
+      things = []
+      @us.by_title do |thing|
+        things << thing
+      end
+      things[0]["doc"]["title"].should =='aaa'
+    end
+    it "should get from specific database" do
+      u = @us.get(@first_id)
+      u.title.should == "aaa"
+    end
+    it "should get first" do
+      u = @us.first
+      u.title.should =~ /\A...\z/
+    end
+    it "should clean up design docs left around on specific database" do
+      @us.by_title
+      @us.all_design_doc_versions["rows"].length.should == 1
+      Unattached.view_by :professor
+      @us.by_professor
+      @us.all_design_doc_versions["rows"].length.should == 2
+      @us.cleanup_design_docs!
+      @us.all_design_doc_versions["rows"].length.should == 1
+    end
+  end
+
   describe "a model with a compound key view" do
     before(:all) do
       Article.design_doc_fresh = false