Support ToString in Linq expressions (NH-2563).

SVN: trunk@5513

Author: patearl

Diff for: src/NHibernate.Test/Linq/FunctionTests.cs

@@ -90,5 +90,25 @@ where e.FirstName.IndexOf("A") == e.BirthDate.Value.Month
 
 			ObjectDumper.Write(query);
 		}
-	}
+
+        [Test]
+        public void ToStringFunction()
+        {
+            var query = from ol in db.OrderLines
+                        where ol.Quantity.ToString() == "4"
+                        select ol;
+
+            Assert.AreEqual(55, query.Count());
+        }
+
+        [Test]
+        public void ToStringWithContains()
+        {
+            var query = from ol in db.OrderLines
+                        where ol.Quantity.ToString().Contains("5")
+                        select ol;
+
+            Assert.AreEqual(498, query.Count());
+        }
+    }
 }

Diff for: src/NHibernate/Linq/Functions/DefaultLinqToHqlGeneratorsRegistry.cs

@@ -18,6 +18,7 @@ public DefaultLinqToHqlGeneratorsRegistry()
 			RegisterGenerator(new DictionaryContainsKeyRuntimeHqlGenerator());
 			RegisterGenerator(new GenericDictionaryItemRuntimeHqlGenerator());
 			RegisterGenerator(new GenericDictionaryContainsKeyRuntimeHqlGenerator());
+            RegisterGenerator(new ToStringRuntimeMethodHqlGenerator());
 
 			this.Merge(new StartsWithGenerator());
 			this.Merge(new EndsWithGenerator());

Diff for: src/NHibernate/Linq/Functions/StringGenerator.cs

@@ -1,3 +1,5 @@
+using System;
+using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Linq.Expressions;
 using System.Reflection;
@@ -193,4 +195,31 @@ public override HqlTreeNode BuildHql(MethodInfo method, Expression targetObject,
 			}
 		}
 
+        public class ToStringRuntimeMethodHqlGenerator : IRuntimeMethodHqlGenerator
+        {
+            private readonly ToStringHqlGeneratorForMethod generator = new ToStringHqlGeneratorForMethod();
+
+            public bool SupportsMethod(MethodInfo method)
+            {
+                return method != null && method.Name == "ToString" && method.GetBaseDefinition().DeclaringType == typeof(object);
+            }
+
+            public IHqlGeneratorForMethod GetMethodGenerator(MethodInfo method)
+            {
+                return generator;
+            }
+        }
+
+        public class ToStringHqlGeneratorForMethod : IHqlGeneratorForMethod
+        {
+            public IEnumerable<MethodInfo> SupportedMethods
+            {
+                get { throw new NotSupportedException(); }
+            }
+
+            public HqlTreeNode BuildHql(MethodInfo method, Expression targetObject, ReadOnlyCollection<Expression> arguments, HqlTreeBuilder treeBuilder, IHqlExpressionVisitor visitor)
+            {
+                return treeBuilder.MethodCall("str", visitor.Visit(targetObject).AsExpression());
+            }
+        }
 }