Don't add new placeholder records to existing DBs. [#4]

lib/ruby/data_table_model.rb

@@ -17,16 +17,18 @@ def initialize(filename)
       end
     end
 
-    # Make some placeholder data for now.
     @data = @db[:table]
-    values = 1.upto(row_count).collect do |r|
-      h = {}
-      1.upto(column_count) do |c|
-        h[:"column_#{c}"] = "R#{r}, C#{c}"
+    if @data.empty?
+      # Make some placeholder data for now.
+      values = 1.upto(row_count).collect do |r|
+        h = {}
+        1.upto(column_count) do |c|
+          h[:"column_#{c}"] = "R#{r}, C#{c}"
+        end
+        h
       end
-      h
+      @data.multi_insert values
     end
-    @data.multi_insert values
   end
 
   def column_count

spec/data_table_model_spec.rb

@@ -31,6 +31,10 @@
       DataTableModel.new filename
       lambda {DataTableModel.new filename}.should_not raise_error
     end
+
+    it "should not add new rows to an existing data table just by opening it" do
+      pending "can't really spec this yet, since row_count is stubbed"
+    end
   end
 
   describe "instance methods" do