Keep NULL values as nil when typecasting

lib/activerecord-postgres-array/string.rb

@@ -26,16 +26,16 @@ def from_postgres_array(base_type = :string)
         res == 'NULL' ? nil : res
       end
 
-      if base_type == :decimal
-        elements.collect(&:to_d)
-      elsif base_type == :float
-        elements.collect(&:to_f)
-      elsif base_type == :integer || base_type == :bigint
-        elements.collect(&:to_i)
-      elsif base_type == :timestamp
-        elements.collect(&:to_time)
-      else
-        elements
+      typecast = {
+        :decimal   => :to_d,
+        :float     => :to_f,
+        :integer   => :to_i,
+        :bigint    => :to_i,
+        :timestamp => :to_time
+      }.fetch(base_type,false)
+
+      elements.map do |e|
+        typecast ? e.try(typecast) : e
       end
     end
   end

spec/string_ext_spec.rb

@@ -105,5 +105,54 @@
     it 'correctly handles multi line content' do
       "{A\nB\nC,X\r\nY\r\nZ}".from_postgres_array.should == ["A\nB\nC", "X\r\nY\r\nZ"]
     end
+
+    it "returns NULL values as nil" do
+      "{NULL,on,Rails}".from_postgres_array.should == [nil, "on", "Rails"]
+    end
+
+    context "with a base_type of :decimal" do
+      it "returns decimal numbers" do
+        "{1.1,2.1,3.1}".from_postgres_array(:decimal).should eql [1.1,2.1,3.1]
+      end
+
+      it "returns NULL values as nil" do
+        "{NULL,2.1,3.1}".from_postgres_array(:decimal).should eql [nil, 2.1, 3.1]
+      end
+    end
+
+    context "with a base_type of :integer" do
+      it "returns integers" do
+        "{1,2,3}".from_postgres_array(:integer).should eql [1,2,3]
+      end
+
+      it "returns NULL values as nil" do
+        "{NULL,2,3}".from_postgres_array(:integer).should eql [nil, 2, 3]
+      end
+    end
+
+    context "with a base_type of :float" do
+      it "returns floats" do
+        "{1,2,3}".from_postgres_array(:float).should eql [1.to_f,2.to_f,3.to_f]
+      end
+
+      it "returns NULL values as nil" do
+        "{NULL,2,3}".from_postgres_array(:float).should eql [nil, 2.to_f, 3.to_f]
+      end
+    end
+
+    context "with a base_type of timestamp" do
+      it "returns time objects" do
+        '{"2004-10-19 10:23:54","2004-10-19 10:23:54"}'.from_postgres_array(:timestamp).should eql [
+          "2004-10-19 10:23:54".to_time,
+          "2004-10-19 10:23:54".to_time 
+        ]
+      end
+
+      it "returns NULL values as nil" do
+        '{NULL,"2004-10-19 10:23:54"}'.from_postgres_array(:timestamp).should eql [
+          nil, "2004-10-19 10:23:54".to_time 
+        ]
+      end
+    end
   end
-end
+end