Append method PostgreSQLCursor::Cursor#size for ActiveRecord collection rendering

Author: ukolovda

README.md

@@ -88,6 +88,17 @@ Product.each_row.map {|r| r["id"].to_i } #=> [1, 2, 3, ...]
 Product.each_instance.map {|r| r.id }.each {|id| p id } #=> [1, 2, 3, ...]
 Product.each_instance.lazy.inject(0) {|sum,r| sum +  r.quantity } #=> 499500
 ```
+
+### PostgreSQLCursor and collection rendering
+       
+You can render cursor collection, using enumeration as collection attribute.
+
+```ruby
+render partial: "some_partial", collection: Product.each_instance
+render partial: "some_partial", collection: Product.each_row
+render partial: "some_partial", collection: Product.each_hash
+```
+
 ### Hashes vs. Instances
 
 The each_row method returns the Hash of strings for speed (as this allows you to process a lot of rows).

lib/postgresql_cursor/cursor.rb

@@ -71,6 +71,12 @@ def iterate_batched(batched = true)
       self
     end
 
+    # ActiveRecord call #size when rendering a collection
+    # Define it and return some dummy value
+    def size
+      -1
+    end
+
     # Public: Yields each row of the result set to the passed block
     #
     # Yields the row to the block. The row is a hash with symbolized keys.

test/test_postgresql_cursor.rb

@@ -225,4 +225,13 @@ def test_relation_association_is_not_loaded
     cursor = Product.first.prices.each_instance
     refute cursor.instance_variable_get(:@type).loaded?
   end
+
+  def test_size
+    r = Product.each_instance
+    assert_equal -1, r.size
+    r = Product.each_hash
+    assert_equal -1, r.size
+    r = Product.each_row
+    assert_equal -1, r.size
+  end
 end