don't rely on First() on a dictionary for default feature support

Dapper NET40/SqlMapper.cs

@@ -4435,28 +4435,27 @@ public void AddParameter(IDbCommand command, string name)
     /// </summary>
     partial class FeatureSupport
     {
-        /// <summary>
-        /// Dictionary of supported features index by connection type name
-        /// </summary>
-        private static readonly Dictionary<string, FeatureSupport> FeatureList = new Dictionary<string, FeatureSupport>(StringComparer.InvariantCultureIgnoreCase) {
-				{"sqlserverconnection", new FeatureSupport { Arrays = false}},
-				{"npgsqlconnection", new FeatureSupport {Arrays = true}}
-		};
+        private static readonly FeatureSupport
+            @default = new FeatureSupport(false),
+            postgres = new FeatureSupport(true);
 
         /// <summary>
         /// Gets the featureset based on the passed connection
         /// </summary>
         public static FeatureSupport Get(IDbConnection connection)
         {
-            string name = connection.GetType().Name;
-            FeatureSupport features;
-            return FeatureList.TryGetValue(name, out features) ? features : FeatureList.Values.First();
+            string name = connection == null ? null : connection.GetType().Name;
+            if (string.Equals(name, "npgsqlconnection", StringComparison.InvariantCultureIgnoreCase)) return postgres;
+            return @default;
+        }
+        private FeatureSupport(bool arrays)
+        {
+            Arrays = arrays;
         }
-
         /// <summary>
         /// True if the db supports array columns e.g. Postgresql
         /// </summary>
-        public bool Arrays { get; set; }
+        public bool Arrays { get; private set; }
     }
 
     /// <summary>

Tests/Tests.cs

@@ -2578,7 +2578,7 @@ public void TestNullFromInt_NoRows()
         public void TestChangingDefaultStringTypeMappingToAnsiString()
         {
             var sql = "SELECT SQL_VARIANT_PROPERTY(CONVERT(sql_variant, @testParam),'BaseType') AS BaseType";
-            var param = new {testParam = "TestString"};
+            var param = new { testParam = "TestString" };
 
             var result01 = connection.Query<string>(sql, param).FirstOrDefault();
             result01.IsEqualTo("nvarchar");
@@ -2913,7 +2913,7 @@ public void DataTableParameters()
             {
                 connection.Query<int>("select count(1) from @ids", new { ids = table.AsTableValuedParameter() }).First();
                 throw new InvalidOperationException();
-            } catch(Exception ex)
+            } catch (Exception ex)
             {
                 ex.Message.Equals("The table type parameter 'ids' must have a valid type name.");
             }
@@ -2982,7 +2982,7 @@ public void GuidIn_SO_24177902()
 
         class HazGeo
         {
-            public int Id { get;set; }
+            public int Id { get; set; }
             public DbGeography Geo { get; set; }
         }
         public void DBGeography_SO24405645_SO24402424()
@@ -3031,7 +3031,7 @@ public void TypeBasedViaTypeMulti()
             Type type = GetSomeType();
 
             dynamic first, second;
-            using(var multi = connection.QueryMultiple("select @A as [A], @B as [B]; select @C as [A], @D as [B]",
+            using (var multi = connection.QueryMultiple("select @A as [A], @B as [B]; select @C as [A], @D as [B]",
                 new { A = 123, B = "abc", C = 456, D = "def" }))
             {
                 first = multi.Read(type).Single();
@@ -3059,14 +3059,14 @@ static Type GetSomeType()
         }
         public class SomeType
         {
-            public int A { get;set; }
-            public string B { get;set; }
+            public int A { get; set; }
+            public string B { get; set; }
         }
 
         class WithInit : ISupportInitialize
         {
             public string Value { get; set; }
-            public int Flags { get;set; }
+            public int Flags { get; set; }
 
             void ISupportInitialize.BeginInit()
             {
@@ -3352,7 +3352,7 @@ public void TestBigIntForEverythingWorks_SqlLite()
         }
         private void TestBigIntForEverythingWorks_SqlLite_ByDataType<T>(string dbType)
         {
-            using(var reader = connection.ExecuteReader("select cast(1 as " + dbType + ")"))
+            using (var reader = connection.ExecuteReader("select cast(1 as " + dbType + ")"))
             {
                 reader.Read().IsTrue();
                 reader.GetFieldType(0).Equals(typeof(T));
@@ -3482,6 +3482,29 @@ public class HazX
         }
 
 
+        public void SO25297173_DynamicIn()
+        {
+            var query = @"
+declare @table table(value int not null);
+insert @table values(1);
+insert @table values(2);
+insert @table values(3);
+insert @table values(4);
+insert @table values(5);
+insert @table values(6);
+insert @table values(7);
+SELECT value FROM @table WHERE value IN @myIds";
+            var queryParams = new Dictionary<string, object> {
+                { "myIds", new [] { 5, 6 } }
+            };
+            
+            var dynamicParams = new DynamicParameters(queryParams);
+            List<int> result = connection.Query<int>(query, dynamicParams).ToList();
+            result.Count.IsEqualTo(2);
+            result.Contains(5).IsTrue();
+            result.Contains(6).IsTrue();
+        }
+
 #if POSTGRESQL
 
         class Cat