diff --git a/Models/XRepositoryDescriptor.cs b/Models/XRepositoryDescriptor.cs
index 00d1252..317c6cb 100644
--- a/Models/XRepositoryDescriptor.cs
+++ b/Models/XRepositoryDescriptor.cs
@@ -1,3 +1,5 @@
+using System;
+using GraphQL.Types;
 using xDataService.Db;
 using xDataService.GraphQL;
 using xDataService.Interfaces;
diff --git a/Providers/XBaseRepositoryService.cs b/Providers/XBaseRepositoryService.cs
index 2233b4a..8954b49 100644
--- a/Providers/XBaseRepositoryService.cs
+++ b/Providers/XBaseRepositoryService.cs
@@ -108,7 +108,7 @@ namespace xDataService.Providers
         /// <param name="saveChanges"></param>
         /// <param name="cancellationToken"></param>
         /// <returns></returns>
-        public async Task<TDto> AddAsync(
+        public virtual async Task<TDto> AddAsync(
             TDto item,
             bool saveChanges = true,
             CancellationToken cancellationToken = default
@@ -155,7 +155,7 @@ namespace xDataService.Providers
         /// <param name="saveChanges"></param>
         /// <param name="cancellationToken"></param>
         /// <returns></returns>
-        public async Task<TDto> AddOrUpdateAsync(
+        public virtual async Task<TDto> AddOrUpdateAsync(
             TDto item,
             bool saveChanges = true,
             CancellationToken cancellationToken = default
@@ -202,15 +202,12 @@ namespace xDataService.Providers
         /// <param name="saveChanges"></param>
         /// <param name="cancellationToken"></param>
         /// <returns></returns>
-        public async Task AddRangeAsync(
+        public virtual async Task AddRangeAsync(
             IEnumerable<TDto> items,
             bool saveChanges = true,
             CancellationToken cancellationToken = default
         )
         {
-            //
-            TDto result = null;
-
             //
             // Validate ...
             bool isValid =
@@ -249,7 +246,7 @@ namespace xDataService.Providers
         /// <param name="saveChanges"></param>
         /// <param name="cancellationToken"></param>
         /// <returns></returns>
-        public async Task<TDto> UpdateAsync(
+        public virtual async Task<TDto> UpdateAsync(
             TKey id,
             TDto item,
             bool saveChanges = true,
@@ -290,7 +287,7 @@ namespace xDataService.Providers
         /// <param name="saveChanges"></param>
         /// <param name="cancellationToken"></param>
         /// <returns></returns>
-        public async Task<bool> UpdateRangeAsync(
+        public virtual async Task<bool> UpdateRangeAsync(
             IEnumerable<TDto> items,
             bool saveChanges = true,
             CancellationToken cancellationToken = default
@@ -339,7 +336,7 @@ namespace xDataService.Providers
         /// <param name="saveChanges"></param>
         /// <param name="cancellationToken"></param>
         /// <returns></returns>
-        public async Task<TDto> RemoveAsync(
+        public virtual async Task<TDto> RemoveAsync(
             TKey id,
             bool softDelete = true,
             bool saveChanges = true,
@@ -378,7 +375,7 @@ namespace xDataService.Providers
         /// <param name="saveChanges"></param>
         /// <param name="cancellationToken"></param>
         /// <returns></returns>
-        public async Task<TDto> RemoveAsync(
+        public virtual async Task<TDto> RemoveAsync(
             TDto item,
             bool softDelete = true,
             bool saveChanges = true,
@@ -420,7 +417,7 @@ namespace xDataService.Providers
         /// <param name="saveChanges"></param>
         /// <param name="cancellationToken"></param>
         /// <returns></returns>
-        public async Task RemoveRangeAsync(
+        public virtual async Task RemoveRangeAsync(
             IEnumerable<TDto> items,
             bool softDelete = true,
             bool saveChanges = true,
@@ -464,7 +461,7 @@ namespace xDataService.Providers
         /// <param name="ignoreSoftDeleteds"></param>
         /// <param name="cancellationToken"></param>
         /// <returns></returns>
-        public async Task<int> CountAsync(
+        public virtual async Task<int> CountAsync(
             bool ignoreSoftDeleteds = true,
             CancellationToken cancellationToken = default
         )
@@ -487,7 +484,7 @@ namespace xDataService.Providers
         /// <param name="ignoreSoftDeleteds"></param>
         /// <param name="cancellationToken"></param>
         /// <returns></returns>
-        public async Task<int> PagesCountAsync(
+        public virtual async Task<int> PagesCountAsync(
             int pageSize,
             int? totalItems = null,
             bool ignoreSoftDeleteds = true,
@@ -516,7 +513,7 @@ namespace xDataService.Providers
         /// <param name="ignoreSoftDeleteds"></param>
         /// <param name="cancellationToken"></param>
         /// <returns></returns>
-        public async Task<bool> IsExistsAsync(
+        public virtual async Task<bool> IsExistsAsync(
             TKey id,
             bool ignoreSoftDeleteds = true,
             CancellationToken cancellationToken = default
@@ -544,7 +541,7 @@ namespace xDataService.Providers
         /// <param name="includeBuilder"></param>
         /// <param name="cancellationToken"></param>
         /// <returns></returns>
-        public async Task<TDto> GetAsync(
+        public virtual async Task<TDto> GetAsync(
             TKey id,
             bool ignoreSoftDeleteds = true,
             Func<IQueryable<TEntity>, IIncludableQueryable<TEntity, object>> includeBuilder = null,
@@ -583,7 +580,7 @@ namespace xDataService.Providers
         /// <param name="includeBuilder"></param>
         /// <param name="cancellationToken"></param>
         /// <returns></returns>
-        public async Task<IEnumerable<TDto>> GetAllAsync(
+        public virtual async Task<IEnumerable<TDto>> GetAllAsync(
             bool ignoreSoftDeleteds = true,
             Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBuilder = null,
             Func<IQueryable<TEntity>, IIncludableQueryable<TEntity, object>> includeBuilder = null,
@@ -623,7 +620,7 @@ namespace xDataService.Providers
         /// <param name="includeBuilder"></param>
         /// <param name="cancellationToken"></param>
         /// <returns></returns>
-        public async IAsyncEnumerable<TDto> GetAllAsAsyncEnumerable(
+        public virtual async IAsyncEnumerable<TDto> GetAllAsAsyncEnumerable(
             bool ignoreSoftDeleteds = true,
             Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBuilder = null,
             Func<IQueryable<TEntity>, IIncludableQueryable<TEntity, object>> includeBuilder = null,
@@ -658,7 +655,7 @@ namespace xDataService.Providers
         /// <param name="includeBuilder"></param>
         /// <param name="cancellationToken"></param>
         /// <returns></returns>
-        public async Task<TDto> FindOneAsync(
+        public virtual async Task<TDto> FindOneAsync(
             Expression<Func<TEntity, bool>> predicate,
             bool ignoreSoftDeleteds = true,
             Func<IQueryable<TEntity>, IIncludableQueryable<TEntity, object>> includeBuilder = null,
@@ -698,7 +695,7 @@ namespace xDataService.Providers
         /// <param name="includeBuilder"></param>
         /// <param name="cancellationToken"></param>
         /// <returns></returns>
-        public async Task<IEnumerable<TDto>> FindManyAsync(
+        public virtual async Task<IEnumerable<TDto>> FindManyAsync(
             Expression<Func<TEntity, bool>> predicate,
             bool ignoreSoftDeleteds = true,
             Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBuilder = null,
@@ -741,7 +738,7 @@ namespace xDataService.Providers
         /// <param name="includeBuilder"></param>
         /// <param name="cancellationToken"></param>
         /// <returns></returns>
-        public async Task<XQueryResult<TDto>> QueryAsync(
+        public virtual async Task<XQueryResult<TDto>> QueryAsync(
             XQuery query,
             bool ignoreSoftDeleteds = true,
             Expression<Func<TEntity, bool>> predicate = null,