- added MapValue(s) to IQueryMapper

Author: eben-roux

Shuttle.Core.Data.Tests/QueryMapper/QueryMapperFixture.cs

@@ -1,4 +1,5 @@
-using System.Linq;
+using System;
+using System.Linq;
 using NUnit.Framework;
 
 namespace Shuttle.Core.Data.Tests
@@ -79,5 +80,33 @@ Age as TheAge
                 Assert.AreEqual(2, mappedRows.Count());
             }
         }
+
+        [Test]
+        public void Should_be_able_to_do_value_mapping()
+        {
+            var mapper = new QueryMapper(new DatabaseGateway());
+
+            var queryRow = RawQuery.Create(@"
+select top 1
+    Id
+from
+    BasicMapping
+");
+
+            var queryRows = RawQuery.Create(@"
+select
+    Id
+from
+    BasicMapping
+");
+
+            using (GetDatabaseContext())
+            {
+                var value = mapper.MapValue<Guid>(queryRow);
+                var values = mapper.MapValues<Guid>(queryRows);
+
+                Assert.AreEqual(2, values.Count());
+            }
+        }
     }
 }

Shuttle.Core.Data/IQueryMapper.cs

@@ -8,5 +8,7 @@ public interface IQueryMapper
         IEnumerable<MappedRow<T>> MapRows<T>(IQuery query) where T : new();
         T MapObject<T>(IQuery query) where T : new();
         IEnumerable<T> MapObjects<T>(IQuery query) where T : new();
+        T MapValue<T>(IQuery query);
+        IEnumerable<T> MapValues<T>(IQuery query);
     }
 }

Shuttle.Core.Data/QueryMapper.cs

@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.Data;
 using System.Linq;
 using System.Reflection;
@@ -19,6 +20,8 @@ public QueryMapper(IDatabaseGateway databaseGateway)
 
         public MappedRow<T> MapRow<T>(IQuery query) where T : new()
         {
+            Guard.AgainstNull(query, "query");
+
             var row = _databaseGateway.GetSingleRowUsing(query);
 
             return new MappedRow<T>(row, Map<T>(row));
@@ -52,17 +55,46 @@ public QueryMapper(IDatabaseGateway databaseGateway)
 
         public IEnumerable<MappedRow<T>> MapRows<T>(IQuery query) where T : new()
         {
+            Guard.AgainstNull(query, "query");
+
             return _databaseGateway.GetRowsUsing(query).Select(row => new MappedRow<T>(row, Map<T>(row)));
         }
 
         public T MapObject<T>(IQuery query) where T : new()
         {
+            Guard.AgainstNull(query, "query");
+
             return Map<T>(_databaseGateway.GetSingleRowUsing(query));
         }
 
         public IEnumerable<T> MapObjects<T>(IQuery query) where T : new()
         {
+            Guard.AgainstNull(query, "query");
+
             return _databaseGateway.GetRowsUsing(query).Select(row => Map<T>(row));
         }
+
+        public T MapValue<T>(IQuery query)
+        {
+            Guard.AgainstNull(query, "query");
+
+            return MapRowValue<T>(_databaseGateway.GetSingleRowUsing(query));
+        }
+
+        public IEnumerable<T> MapValues<T>(IQuery query)
+        {
+            Guard.AgainstNull(query, "query");
+
+            return _databaseGateway.GetRowsUsing(query).Select(row => MapRowValue<T>(row));
+        }
+
+        private T MapRowValue<T>(DataRow row)
+        {
+            var underlyingSystemType = Nullable.GetUnderlyingType(typeof(T)) ?? typeof(T);
+
+            return row[0] == null
+                        ? default(T)
+                        : (T)Convert.ChangeType(row[0], underlyingSystemType);
+        }
     }
 }