fix guid casting

Author: giometrix

src/TableStorage.Abstractions.TableEntityConverters/EntityConvert.cs

@@ -46,8 +46,19 @@ public static T FromTableEntity<T, TP, TR>(this DynamicTableEntity entity,
             Expression<Func<T, object>> partitionProperty,
             Expression<Func<T, object>> rowProperty) where T : new()
         {
-            return FromTableEntity(entity, partitionProperty, p => Convert.ChangeType(entity.PartitionKey, typeof(TP)),
-                rowProperty, p => Convert.ChangeType(entity.RowKey, typeof(TR)));
+            var convertPartition = new Func<string,TP>(p=>(TP)Convert.ChangeType(p, typeof(TP)));
+            var convertRow = new Func<string,TR>(r =>(TR)Convert.ChangeType(r, typeof(TR)));
+
+            if (typeof(TP) == typeof(Guid))
+            {
+                convertPartition = p=>(TP)(object)Guid.Parse(p);
+            }
+            if (typeof(TR) == typeof(Guid))
+            {
+                convertRow = r => (TR)(object)Guid.Parse(r);
+            }
+            return FromTableEntity(entity, partitionProperty, convertPartition,
+                rowProperty, convertRow);
         }
 
         public static T FromTableEntity<T, TP, TR>(this DynamicTableEntity entity,

src/TableStorage.Abstractions.UnitTests/EntityConvertTests.cs

@@ -118,5 +118,26 @@ public void convert_from_entity_table_unmapped_partition_key()
 
             Assert.Equal(Guid.Parse("12ae85a4-7131-4e8c-af63-074b066412e0"), employee.Department.OptionalId);
         }
+
+        public class GuidKeyTest
+        {
+            public Guid A { get; set; }
+            public Guid B { get; set; }
+        }
+
+        [Fact]
+        public void convert_from_entity_table_with_guid_keys()
+        {
+            Guid a = Guid.Parse("7ba5bd25-823e-4c01-940e-1f131cbed8ed");
+            Guid b = Guid.Parse("603e51de-950e-4270-a755-c26950742103");
+
+            var obj = new GuidKeyTest{A = a, B = b};
+            var e = obj.ToTableEntity(x => x.A, x => x.B);
+            var convertedObject = e.FromTableEntity<GuidKeyTest, Guid, Guid>(x => x.A, x => x.B);
+
+
+            Assert.Equal(a, convertedObject.A);
+
+        }
     }
 }