Fix for Serialization and Deserialization issues.

Author: Jay Oursler

MicroRuleEngine.Core.Tests/ExampleUsage.cs

@@ -4,6 +4,7 @@
 using System.Linq.Expressions;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MicroRuleEngine.Core.Tests.Models;
+using Newtonsoft.Json;
 
 namespace MicroRuleEngine.Tests
 {
@@ -392,5 +393,46 @@ public void EnumerableAggregationOnChild()
 
             Assert.IsTrue(passes);
         }
+
+        [TestMethod]
+        public void SerializeThenDeserialize()
+        {
+            
+
+
+            Order order = GetOrder();
+
+            var orderParent = new OrderParent() {PlacedOrder = order};
+
+
+            Rule rule = new Rule
+                        {
+                            MemberName = "PlacedOrder.Items",
+                            EnumerableValueExpression = new Selector
+                                                        {
+                                                            Operator = "Count"
+                                                        },
+                            Operator    = "GreaterThan",
+                            TargetValue = 3
+                        };
+
+            var jsonString = JsonConvert.SerializeObject(rule);
+
+            var deserializedRule = JsonConvert.DeserializeObject<Rule>(jsonString);
+
+
+
+            MRE  engine       = new MRE();
+            var  compiledRule = engine.CompileRule<OrderParent>(deserializedRule);
+            bool passes       = compiledRule(orderParent);
+            Assert.IsFalse(passes);
+
+            order.Items.Add(new Item());
+            order.Items.Add(new Item());
+
+            passes = compiledRule(orderParent);
+
+            Assert.IsTrue(passes);
+        }
     }
 }

MicroRuleEngine/MRE.cs

@@ -328,10 +328,22 @@ private static Expression BuildExpr(Type type, Rule rule, Expression param, bool
                                                                 2,
                                                property.PropertyType);
 
+                    
+
                     if(generationMethod == null)
                     {
                         generationMethod = GetLinqMethod(rule.EnumerableValueExpression.Operator, rule.TargetValue.GetType());
                     }
+                    if(generationMethod == null)
+                    {
+                        generationMethod = GetLinqMethod(rule.EnumerableValueExpression.Operator);
+                    }
+
+                    if (generationMethod == null)
+                    {
+                        throw new
+                            RulesException($"Unable to find Linq method for {rule.EnumerableValueExpression.Operator}");
+                    }
 
                     var m = generationMethod.MakeGenericMethod(elementType);
 
@@ -492,6 +504,12 @@ private static MethodInfo GetLinqMethod(string name, Type returnType)
                                      .FirstOrDefault((m => m.Name == name && m.ReturnType == returnType));
         }
 
+        private static MethodInfo GetLinqMethod(string name)
+        {
+            return typeof(Enumerable).GetMethods(BindingFlags.Static | BindingFlags.Public)
+                                     .FirstOrDefault((m => m.Name == name));
+        }
+
 
 
         private static Expression GetDataRowField(Expression prm, string member, string typeName)