returning nil for tables that do not exist

2 files changed, 21 insertions, 21 deletions

diff --git a/lib/arel/table.rb b/lib/arel/table.rb
index 06bbe7b99e..d23245691b 100644
--- a/lib/arel/table.rb
+++ b/lib/arel/table.rb
@@ -88,8 +88,24 @@ module Arel
     end
 
     def [] name
+      return nil unless table_exists?
+
       name = name.to_sym
       columns.find { |column| column.name == name }
     end
+
+    private
+    def table_exists?
+      @table_exists ||= tables.key?(@name) || engine.connection.table_exists?(name)
+    end
+
+    def tables
+      self.class.table_cache(@engine)
+    end
+
+    @@table_cache = nil
+    def self.table_cache engine # :nodoc:
+      @@table_cache ||= Hash[engine.connection.tables.map { |x| [x,true] }]
+    end
   end
 end
diff --git a/spec/arel/table_spec.rb b/spec/arel/table_spec.rb
index 5b68040aac..28fc95dec5 100644
--- a/spec/arel/table_spec.rb
+++ b/spec/arel/table_spec.rb
@@ -147,27 +147,11 @@ module Arel
         end
       end
 
-      ### FIXME: this seems like a bad requirement.
-      #describe 'when given an', Attribute do
-      #  it "returns the attribute if the attribute is within the relation" do
-      #    @relation[@relation[:id]].should == @relation[:id]
-      #  end
-
-      #  it "returns nil if the attribtue is not within the relation" do
-      #    another_relation = Table.new(:photos)
-      #    @relation[another_relation[:id]].should be_nil
-      #  end
-      #end
-
-      #describe 'when given an', Expression do
-      #  before do
-      #    @expression = @relation[:id].count
-      #  end
-
-      #  it "returns the Expression if the Expression is within the relation" do
-      #    @relation[@expression].should be_nil
-      #  end
-      #end
+      describe 'when table does not exist' do
+        it 'returns nil' do
+          @relation[:foooo].should be_nil
+        end
+      end
     end
   end
 end