Fixed issue with datatable.Fill with nullable columns #539

ClickHouse.Client.Tests/SqlSchemaTests.cs

@@ -1,7 +1,11 @@
-using System.Data.Common;
+using System.Data;
+using System;
+using System.Data.Common;
+using System.Reflection.PortableExecutable;
 using System.Threading.Tasks;
 using ClickHouse.Client.Utility;
 using NUnit.Framework;
+using System.Linq;
 
 namespace ClickHouse.Client.Tests;
 
@@ -24,4 +28,22 @@ public async Task ShouldGetReaderSchemaTable()
         var schema = reader.GetSchemaTable();
         Assert.AreEqual(2, schema.Rows.Count);
     }
+
+    [Test]
+    public void ShouldGetSchemaTableAsDataTable()
+    {
+        using var command = connection.CreateCommand();
+        command.CommandText = "SELECT name, total_rows from system.tables";
+        using var reader = command.ExecuteReader();
+        var table = new DataTable();
+        try { 
+            table.Load(reader);
+        }
+        catch
+        {
+
+        }
+        var errors = table.GetErrors().Select(e => e.RowError).ToList();
+        CollectionAssert.IsEmpty(errors);
+    }
 }

ClickHouse.Client/Utility/SchemaDescriber.cs

@@ -40,7 +40,8 @@ public static DataTable DescribeSchema(this ClickHouseDataReader reader)
             var row = table.NewRow();
             row["ColumnName"] = reader.GetName(ordinal);
             row["ColumnOrdinal"] = ordinal;
-            row["DataType"] = chType.FrameworkType;
+            row["ColumnSize"] = -1;
+            row["DataType"] = chType is NullableType nt ? nt.UnderlyingType.FrameworkType : chType.FrameworkType;
             row["ProviderType"] = chType;
             row["IsLong"] = chType is StringType;
             row["AllowDBNull"] = chType is NullableType;