string and byte[] : add UseGetFieldValue (#2050)

* string and byte[] : add UseGetFieldValue to prevent problems with npgsql using global deserializer
* switch to GetFieldValue<T> changes some messaging in invalid cast scenarios; if anything, new version is clearer, so: fine
* test fixes

Author: mgravell

Dapper.sln

@@ -15,6 +15,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution
 		global.json = global.json
 		docs\index.md = docs\index.md
 		License.txt = License.txt
+		.github\workflows\main.yml = .github\workflows\main.yml
 		nuget.config = nuget.config
 		Readme.md = Readme.md
 		version.json = version.json

Dapper/SqlMapper.cs

@@ -192,7 +192,9 @@ public TypeMapEntry(DbType dbType, TypeMapEntryFlags flags)
             public bool Equals(TypeMapEntry other) => other.DbType == DbType && other.Flags == Flags;
             public static readonly TypeMapEntry
                 DoNotSet = new((DbType)(-2), TypeMapEntryFlags.None),
-                DecimalFieldValue = new(DbType.Decimal, TypeMapEntryFlags.SetType | TypeMapEntryFlags.UseGetFieldValue);
+                DecimalFieldValue = new(DbType.Decimal, TypeMapEntryFlags.SetType | TypeMapEntryFlags.UseGetFieldValue),
+                StringFieldValue = new(DbType.String, TypeMapEntryFlags.SetType | TypeMapEntryFlags.UseGetFieldValue),
+                BinaryFieldValue = new(DbType.Binary, TypeMapEntryFlags.SetType | TypeMapEntryFlags.UseGetFieldValue);
 
             public static implicit operator TypeMapEntry(DbType dbType)
                 => new(dbType, TypeMapEntryFlags.SetType);
@@ -214,13 +216,13 @@ static SqlMapper()
                 [typeof(double)] = DbType.Double,
                 [typeof(decimal)] = DbType.Decimal,
                 [typeof(bool)] = DbType.Boolean,
-                [typeof(string)] = DbType.String,
+                [typeof(string)] = TypeMapEntry.StringFieldValue,
                 [typeof(char)] = DbType.StringFixedLength,
                 [typeof(Guid)] = DbType.Guid,
                 [typeof(DateTime)] = TypeMapEntry.DoNotSet,
                 [typeof(DateTimeOffset)] = DbType.DateTimeOffset,
                 [typeof(TimeSpan)] = TypeMapEntry.DoNotSet,
-                [typeof(byte[])] = DbType.Binary,
+                [typeof(byte[])] = TypeMapEntry.BinaryFieldValue,
                 [typeof(byte?)] = DbType.Byte,
                 [typeof(sbyte?)] = DbType.SByte,
                 [typeof(short?)] = DbType.Int16,
@@ -3905,7 +3907,11 @@ public static void ThrowDataException(Exception ex, int index, IDataReader reade
                     }
                     try
                     {
-                        if (value is null || value is DBNull)
+                        if (value is null && ex is InvalidCastException)
+                        {
+                            formattedValue = "n/a - " + ex.Message; // provide some context
+                        }
+                        else if (value is null || value is DBNull)
                         {
                             formattedValue = "<null>";
                         }

global.json

@@ -1,5 +1,6 @@
 {
   "sdk": {
-    "version": "8.0.100"
+    "version": "8.0.100",
+    "rollForward": "latestMajor"
   }
 }

tests/Dapper.Tests/MiscTests.cs

@@ -265,7 +265,7 @@ static async Task TestExceptionsAsync<T>(DbConnection connection, string sql, st
             await TestExceptionsAsync<int>(
                 connection,
                 "Select null as Foo",
-                "Error parsing column 0 (Foo=<null>)");
+                "Error parsing column 0 (Foo=n/a - Null object cannot be converted to a value type.)");
             // Incompatible value throws (testing unnamed column bits here too)
             await TestExceptionsAsync<int>(
                 connection,

tests/Dapper.Tests/TypeHandlerTests.cs

@@ -28,12 +28,12 @@ public void TestChangingDefaultStringTypeMappingToAnsiString()
 
             SqlMapper.PurgeQueryCache();
 
-            SqlMapper.AddTypeMap(typeof(string), DbType.AnsiString);   // Change Default String Handling to AnsiString
+            SqlMapper.AddTypeMap(typeof(string), DbType.AnsiString, true); // Change Default String Handling to AnsiString
             var result02 = connection.Query<string>(sql, param).FirstOrDefault();
             Assert.Equal("varchar", result02);
 
             SqlMapper.PurgeQueryCache();
-            SqlMapper.AddTypeMap(typeof(string), DbType.String);  // Restore Default to Unicode String
+            SqlMapper.AddTypeMap(typeof(string), DbType.String, true);  // Restore Default to Unicode String
         }
 
         [Fact]
@@ -47,12 +47,12 @@ public void TestChangingDefaultStringTypeMappingToAnsiStringFirstOrDefault()
 
             SqlMapper.PurgeQueryCache();
 
-            SqlMapper.AddTypeMap(typeof(string), DbType.AnsiString);   // Change Default String Handling to AnsiString
+            SqlMapper.AddTypeMap(typeof(string), DbType.AnsiString, true); // Change Default String Handling to AnsiString
             var result02 = connection.QueryFirstOrDefault<string>(sql, param);
             Assert.Equal("varchar", result02);
 
             SqlMapper.PurgeQueryCache();
-            SqlMapper.AddTypeMap(typeof(string), DbType.String);  // Restore Default to Unicode String
+            SqlMapper.AddTypeMap(typeof(string), DbType.String, true);  // Restore Default to Unicode String
         }
 
         [Fact]
@@ -643,7 +643,7 @@ public void Issue149_TypeMismatch_SequentialAccess()
         {
             Guid guid = Guid.Parse("cf0ef7ac-b6fe-4e24-aeda-a2b45bb5654e");
             var ex = Assert.ThrowsAny<Exception>(() => connection.Query<Issue149_Person>("select @guid as Id", new { guid }).First());
-            Assert.Equal("Error parsing column 0 (Id=cf0ef7ac-b6fe-4e24-aeda-a2b45bb5654e - Object)", ex.Message);
+            Assert.Equal("Error parsing column 0 (Id=n/a - Unable to cast object of type 'System.Guid' to type 'System.String'.)", ex.Message);
         }
 
         public class Issue149_Person { public string? Id { get; set; } }