diff --git a/PoweredSoft.DynamicQuery.Cli/Program.cs b/PoweredSoft.DynamicQuery.Cli/Program.cs
index da7f35f..b2a5a7c 100644
--- a/PoweredSoft.DynamicQuery.Cli/Program.cs
+++ b/PoweredSoft.DynamicQuery.Cli/Program.cs
@@ -8,6 +8,7 @@ using Newtonsoft.Json.Converters;
 namespace PoweredSoft.DynamicQuery.Cli
 {
     public class PersonQueryInterceptor : IQueryInterceptor
+        , IAggregateInterceptor
         //, IBeforeQueryAlteredInterceptor<Person>
         //, IFilterInterceptor
     {
@@ -40,6 +41,13 @@ namespace PoweredSoft.DynamicQuery.Cli
 
             return filter;
         }
+
+        public IAggregate InterceptAggregate(IAggregate aggregate)
+        {
+            if (aggregate.Path == nameof(Person.AgeStr))
+                return new Aggregate {Type = aggregate.Type, Path = nameof(Person.Age)};
+            return aggregate;
+        }
     }
 
     public class Person
@@ -49,6 +57,7 @@ namespace PoweredSoft.DynamicQuery.Cli
         public string LastName { get; set; }
         public int Age { get; set; }
         public string Sexe { get; set; }
+        public string AgeStr => $"{Age} years old";
     }
 
     public class OtherClass
@@ -69,7 +78,7 @@ namespace PoweredSoft.DynamicQuery.Cli
         {
             var list = new List<Person>()
             {
-                new Person{ Id = 1, FirstName = "David", LastName = "Lebee", Sexe = "Male", Age = 29},
+                new Person{ Id = 1, FirstName = "David", LastName = "Lebee", Sexe = "Male", Age = 29 },
                 new Person{ Id = 2, FirstName = "Michaela", LastName = "Lebee", Sexe = "Female", Age = 29},
                 new Person{ Id = 3, FirstName = "Zohra", LastName = "Lebee", Sexe = "Female", Age = 20},
                 new Person{ Id = 4, FirstName = "Eric", LastName = "Vickar", Sexe = "Male", Age = 30},
@@ -90,7 +99,7 @@ namespace PoweredSoft.DynamicQuery.Cli
             criteria.Aggregates = new List<IAggregate>()
             {
                 new Aggregate { Type = AggregateType.Count },
-                new Aggregate { Path = "Age", Type = AggregateType.Avg }
+                new Aggregate { Path = "AgeStr", Type = AggregateType.Avg }
             };;
 
             var handler = new QueryHandler();
diff --git a/PoweredSoft.DynamicQuery.Core/IAggregateInterceptor.cs b/PoweredSoft.DynamicQuery.Core/IAggregateInterceptor.cs
new file mode 100644
index 0000000..a5aac21
--- /dev/null
+++ b/PoweredSoft.DynamicQuery.Core/IAggregateInterceptor.cs
@@ -0,0 +1,11 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace PoweredSoft.DynamicQuery.Core
+{
+    public interface IAggregateInterceptor : IQueryInterceptor
+    {
+        IAggregate InterceptAggregate(IAggregate aggregate);
+    }
+}
diff --git a/PoweredSoft.DynamicQuery/QueryHandler.cs b/PoweredSoft.DynamicQuery/QueryHandler.cs
index 7e42010..4a26c34 100644
--- a/PoweredSoft.DynamicQuery/QueryHandler.cs
+++ b/PoweredSoft.DynamicQuery/QueryHandler.cs
@@ -36,7 +36,7 @@ namespace PoweredSoft.DynamicQuery
             var finalGroups = Criteria.Groups.Select(g => InterceptGroup<T>(g)).ToList();
 
             // get the aggregates.
-            var aggregateResults = Criteria.Aggregates.Any() ? FetchAggregates(finalGroups) : null;
+            var aggregateResults = FetchAggregates<T>(finalGroups);
 
             // sorting.
             finalGroups.ForEach(fg => Criteria.Sorts.Insert(0, new Sort(fg.Path, fg.Ascending)));
@@ -101,11 +101,11 @@ namespace PoweredSoft.DynamicQuery
                 return (object)groupRecordResult;
             }).ToList();
 
-            result.Aggregates = CalculateTotalAggregate(queryableAfterFilters);
+            result.Aggregates = CalculateTotalAggregate<T>(queryableAfterFilters);
             return result;
         }
 
-        protected virtual List<IAggregateResult> CalculateTotalAggregate(IQueryable queryableAfterFilters)
+        protected virtual List<IAggregateResult> CalculateTotalAggregate<T>(IQueryable queryableAfterFilters)
         {
             if (!Criteria.Aggregates.Any())
                 return null;
@@ -115,8 +115,9 @@ namespace PoweredSoft.DynamicQuery
             {
                 Criteria.Aggregates.ForEach((a, index) =>
                 {
-                    var selectType = ResolveSelectFrom(a.Type);
-                    sb.Aggregate(a.Path, selectType, $"Agg_{index}");
+                    var fa = InterceptAggregate<T>(a);
+                    var selectType = ResolveSelectFrom(fa.Type);
+                    sb.Aggregate(fa.Path, selectType, $"Agg_{index}");
                 });
             });
 
@@ -153,8 +154,11 @@ namespace PoweredSoft.DynamicQuery
         }
 
 
-        private List<List<DynamicClass>> FetchAggregates(List<IGroup> finalGroups)
+        private List<List<DynamicClass>> FetchAggregates<T>(List<IGroup> finalGroups)
         {
+            if (!Criteria.Aggregates.Any())
+                return null;
+
             List<List<DynamicClass>> aggregateResults;
             var previousGroups = new List<IGroup>();
             aggregateResults = finalGroups.Select(fg =>
@@ -173,8 +177,9 @@ namespace PoweredSoft.DynamicQuery
                     sb.Key($"Key_{++groupKeyIndex}", $"Key_{groupKeyIndex}");
                     Criteria.Aggregates.ForEach((a, ai) =>
                     {
-                        var selectType = ResolveSelectFrom(a.Type);
-                        sb.Aggregate(a.Path, selectType, $"Agg_{ai}");
+                        var fa = InterceptAggregate<T>(a);
+                        var selectType = ResolveSelectFrom(fa.Type);
+                        sb.Aggregate(fa.Path, selectType, $"Agg_{ai}");
                     });
                 });
 
@@ -202,7 +207,7 @@ namespace PoweredSoft.DynamicQuery
             
             // the data.
             result.Data = CurrentQueryable.ToObjectList();
-            result.Aggregates = CalculateTotalAggregate(afterFilterQueryable);
+            result.Aggregates = CalculateTotalAggregate<T>(afterFilterQueryable);
 
             return result;
         }
diff --git a/PoweredSoft.DynamicQuery/QueryHandlerBase.cs b/PoweredSoft.DynamicQuery/QueryHandlerBase.cs
index 50d0b50..842292c 100644
--- a/PoweredSoft.DynamicQuery/QueryHandlerBase.cs
+++ b/PoweredSoft.DynamicQuery/QueryHandlerBase.cs
@@ -6,6 +6,7 @@ using System.Diagnostics;
 using System.Linq;
 using System.Net;
 using System.Reflection;
+using System.Runtime.CompilerServices;
 using System.Text;
 using System.Threading.Tasks;
 using PoweredSoft.DynamicLinq.Fluent;
@@ -86,6 +87,14 @@ namespace PoweredSoft.DynamicQuery
                 result.NumberOfPages = result.TotalRecords / Criteria.PageSize + (result.TotalRecords % Criteria.PageSize != 0 ? 1 : 0);
         }
 
+        protected virtual IAggregate InterceptAggregate<T>(IAggregate aggregate)
+        {
+            var ret = Interceptors
+                .Where(t => t is IAggregateInterceptor)
+                .Cast<IAggregateInterceptor>()
+                .Aggregate(aggregate, (prev, inter) => inter.InterceptAggregate(prev));
+            return ret;
+        }
 
         protected virtual List<ISort> InterceptSort<T>(ISort sort)
         {