Support "ToString" in VisitColumnAccessMethod.

Author: OlegNadymov

src/ServiceStack.OrmLite/Expressions/SqlExpression.cs

@@ -2140,6 +2140,16 @@ protected virtual object VisitColumnAccessMethod(MethodCallExpression m)
                         statement = GetSubstringSql(quotedColName, startIndex);
                     }
                     break;
+                case "ToString":
+                    if (m.Object.Type == typeof(string))
+                    {
+                        statement = string.Format("({0})", quotedColName);
+                    }
+                    else
+                    {
+                        statement = string.Format("cast({0} as varchar(1000))", quotedColName);
+                    }
+                    break;
                 default:
                     throw new NotSupportedException();
             }

tests/ServiceStack.OrmLite.Tests/ExpressionVisitorTests.cs

@@ -413,6 +413,51 @@ public void Can_Where_using_filter_with_nested_properties()
             Assert.That(target.Count, Is.EqualTo(1));
         }
 
+        [Test]
+        public void Can_Where_using_filter_with_ToString()
+        {
+            string filterText = "10";
+            int filterInt = 10;
+            
+            var q = Db.From<TestType>().Where(x => x.NullableIntCol.ToString() == filterText);
+            var target = Db.Select(q);
+            Assert.That(target.Count, Is.EqualTo(1));
+
+            q = Db.From<TestType>().Where(x => x.NullableIntCol.ToString() == null);
+            target = Db.Select(q);
+            Assert.That(target.Count, Is.EqualTo(1));
+
+            q = Db.From<TestType>().Where(x => x.NullableIntCol.ToString() == filterInt.ToString());
+            target = Db.Select(q);
+            Assert.That(target.Count, Is.EqualTo(1));
+            
+            q = Db.From<TestType>().Where(x => x.NullableIntCol.ToString() == "NotNumeric");
+            target = Db.Select(q);
+            Assert.That(target.Count, Is.EqualTo(0));
+
+            q = Db.From<TestType>().
+                Join<TestType2>().
+                Where( x => x.NullableIntCol.ToString() == filterText && x.TestType2ObjCol.NullableIntCol.ToString() == filterText);
+            target = Db.Select(q);
+            Assert.That(target.Count, Is.EqualTo(1));
+
+            q = Db.From<TestType>().
+                Join<TestType2>().
+                Where(x => x.NullableIntCol.ToString() == filterText && x.TestType2ObjCol.NullableIntCol.ToString() == "NotNumeric");
+            target = Db.Select(q);
+            Assert.That(target.Count, Is.EqualTo(0));
+
+            var filterText2 = "qwer";
+
+            q = Db.From<TestType>().Where(x => x.TextCol.ToString() == filterText2);
+            target = Db.Select(q);
+            Assert.That(target.Count, Is.EqualTo(1));
+
+            q = Db.From<TestType>().Where(x => x.NullableIntCol.ToString().EndsWith("0"));
+            target = Db.Select(q);
+            Assert.That(target.Count, Is.EqualTo(3));
+        }
+
         private int MethodReturningInt(int val)
         {
             return val;