From f22447dfe8e6cc9fa2fd5b101cba528da89433fd Mon Sep 17 00:00:00 2001
From: Marc Gravell <marc.gravell@gmail.com>
Date: Wed, 10 Oct 2012 12:17:47 +0100
Subject: [PATCH] Give more context when the GridReader is disposed; see
 http://stackoverflow.com/questions/12809907/

---
 Dapper/SqlMapper.cs |  6 +++---
 Tests/Tests.cs      | 25 +++++++++++++++++++++++++
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/Dapper/SqlMapper.cs b/Dapper/SqlMapper.cs
index ff3915a0..a458d86e 100644
--- a/Dapper/SqlMapper.cs
+++ b/Dapper/SqlMapper.cs
@@ -2280,7 +2280,7 @@ this IDbConnection cnn, string sql, Func<TFirst, TSecond, TThird, TFourth, TRetu
             /// </summary>
             public IEnumerable<T> Read<T>()
             {
-                if (reader == null) throw new ObjectDisposedException(GetType().Name);
+                if (reader == null) throw new ObjectDisposedException(GetType().FullName, "The reader has been disposed; this can happen after all data has been consumed");
                 if (consumed) throw new InvalidOperationException("Each grid can only be iterated once");
                 var typedIdentity = identity.ForGrid(typeof(T), gridIndex);
                 CacheInfo cache = GetCacheInfo(typedIdentity);
@@ -2298,7 +2298,6 @@ this IDbConnection cnn, string sql, Func<TFirst, TSecond, TThird, TFourth, TRetu
 
             private IEnumerable<TReturn> MultiReadInternal<TFirst, TSecond, TThird, TFourth, TFifth, TReturn>(object func, string splitOn)
             {
-
                 var identity = this.identity.ForGrid(typeof(TReturn), new Type[] { 
                     typeof(TFirst), 
                     typeof(TSecond),
@@ -2413,12 +2412,13 @@ this IDbConnection cnn, string sql, Func<TFirst, TSecond, TThird, TFourth, TRetu
                     }
                 }
             }
-            private int gridIndex;
+            private int gridIndex, readCount;
             private bool consumed;
             private void NextResult()
             {
                 if (reader.NextResult())
                 {
+                    readCount++;
                     gridIndex++;
                     consumed = false;
                 }
diff --git a/Tests/Tests.cs b/Tests/Tests.cs
index 08a25912..b9e28b90 100644
--- a/Tests/Tests.cs
+++ b/Tests/Tests.cs
@@ -2096,6 +2096,31 @@ end");
             }
         }
 
+        public void TestMultiSelectWithSomeEmptyGrids()
+        {
+            using (var reader = connection.QueryMultiple("select 1; select 2 where 1 = 0; select 3 where 1 = 0; select 4;"))
+            {
+                var one = reader.Read<int>().ToArray();
+                var two = reader.Read<int>().ToArray();
+                var three = reader.Read<int>().ToArray();
+                var four = reader.Read<int>().ToArray();
+                try { // only returned four grids; expect a fifth read to fail
+                    reader.Read<int>();
+                    throw new InvalidOperationException("this should not have worked!");
+                }
+                catch (ObjectDisposedException ex) { // expected; success
+                    ex.Message.IsEqualTo("The reader has been disposed; this can happen after all data has been consumed\r\nObject name: 'Dapper.SqlMapper+GridReader'.");
+                }
+
+                one.Length.IsEqualTo(1);
+                one[0].IsEqualTo(1);
+                two.Length.IsEqualTo(0);
+                three.Length.IsEqualTo(0);
+                four.Length.IsEqualTo(1);
+                four[0].IsEqualTo(4);
+            }
+        }
+
         class TransactedConnection : IDbConnection
         {
             IDbConnection _conn;