handle empty datasets correctly

VERSION

@@ -1 +1 @@
-0.1.4
+0.1.5

lib/extensions/export.rb

@@ -31,8 +31,11 @@ def initialize(fd, dataset, options)
       end
 
       def output 
+        first_row = @dataset.first
+        return unless first_row
+
         quot = @options[:quote_char]
-        @columns ||= @dataset.first.keys.sort_by{|x|x.to_s}
+        @columns ||= first_row.keys.sort_by{|x|x.to_s}
 
         if @options[:headers] == true
           @file.puts @columns.map{|col| "#{quot}#{col}#{quot}"}.join(@options[:delimiter])

test/test_export.rb

@@ -50,6 +50,13 @@ module ExportTest
       DB[:nodes].all.size.should == 12
     end
 
+    it "should do nothing with empty result sets" do
+      mem_stream = StringIO.new("", "w+")
+      DB[:nodes].filter(:name => 'bogus').export(mem_stream)
+      mem_stream.pos = 0
+      mem_stream.read.should == ""
+    end
+
     it "should export everything tab delimited w/o quotes" do 
       mem_stream = StringIO.new("", "w+")
       DB[:nodes].export(mem_stream)