C# EntityManager.SaveChanges方法代码示例

        public async Task SimpleConcurrencyFault() {

            Configuration.Instance.ProbeAssemblies(typeof(Customer).Assembly);

            // Query Alfred
            var entityManager1 = new EntityManager(_northwindServiceName);
            var query = new EntityQuery<Customer>().Where(c => c.CustomerID == _alfredsID);
            var alfred1 = (await entityManager1.ExecuteQuery(query)).FirstOrDefault();

            // Query a second copy of Alfred in a second entity manager
            var entityManager2 = new EntityManager(_northwindServiceName);
            var alfred2 = (await entityManager2.ExecuteQuery(query)).FirstOrDefault();

            // Modify and save the first Alfred
            alfred1.ContactTitle += "X";

            // Currently, this throws due to "changes to an original record may not be saved"
            // ...whatever that means
            var saveResult1 = await entityManager1.SaveChanges();

            // Attempt to modify and save the second Alfred
            alfred2.ContactName += "Y";
            try {
                var saveResult2 = await entityManager2.SaveChanges();
            }
            catch (SaveException e) {
                var message = e.Message;
            }
        }

        public async Task QueryWithAFilter()
        {
            var manager = new EntityManager(_serviceName);

            // Metadata must be fetched before CreateEntity() can be called
            await manager.FetchMetadata();

            // Ensure there is at least one active todo item named Wine in the database
            var wines = await new EntityQuery<TodoItem>().Where(td => td.Description == "Wine" && !td.IsArchived && !td.IsDone).Execute(manager);
            if (!wines.Any()) {
                var newWine = manager.CreateEntity<TodoItem>(new {Description = "Wine"});
                await manager.SaveChanges();
            }
            manager.Clear();

            //Snippet1
            var query1 = new EntityQuery<TodoItem>();
            var allTodos = await manager.ExecuteQuery(query1);
            Assert.IsTrue(allTodos.Any(), "No TodoItems in the database");
            
            //Snippet2
            var query2 = query1.Where(td => !td.IsArchived);
            var unarchivedTodos = await manager.ExecuteQuery(query2);
            Assert.IsTrue(unarchivedTodos.Any(), "No unarchived TodoItems in the database");

            //Snippet3
            var query3 = query1.Where(td => !td.IsArchived && !td.IsDone);
            var activeTodos = await manager.ExecuteQuery(query3);
            Assert.IsTrue(activeTodos.Any(), "No active TodoItems in the database");

            //Snippet4
            var query4 = query1.Where(td => td.Description.Contains("Wine"));
            var wineTodos = await manager.ExecuteQuery(query4);
            Assert.IsTrue(allTodos.Any(), "No Wine TodoItems in the database");

            //Snippet5
            // Execute above query locally
            var localWineTodos = manager.ExecuteQueryLocally(query4);
            Assert.AreEqual(wineTodos.Count(), localWineTodos.Count(), "Got " + localWineTodos.Count() + " local wine TodoItems");
        }

 private async Task UpdateProduct(EntityManager em, int productID) {
   //  ok(true, "TODO for Mongo - needs to be written specifically for Mongo - should succeed in Mongo");
   var q0 = new EntityQuery<Product>().Where(p => p.ProductID == productID);
   var r0 = await em.ExecuteQuery(q0);
   Assert.IsTrue(r0.Count() == 1, "should be 1 result");
   var prod = r0.First();
   prod.UnitsInStock = (short)(prod.UnitsInStock.HasValue ? prod.UnitsInStock.Value + 1 : 1);
   var sr0 = await em.SaveChanges();
   Assert.IsTrue(sr0.Entities.Count == 1);
 }

    public async Task DeleteWithoutQuery() {
      var em1 = await TestFns.NewEm(_serviceName);

      var emp = new Employee();
      emp.FirstName = "Test Fn";
      emp.LastName = "Test Fn";
      em1.AddEntity(emp);
      var sr = await em1.SaveChanges();

      Assert.IsTrue(sr.Entities.Count == 1, "should have saved 1 entity");
      Assert.IsTrue(sr.Entities.First() == emp, "should be the same emp");
      var em2 = new EntityManager(em1);
      em2.ImportEntities(em1.ExportEntities());
      var sameEmp = (Employee) em2.GetEntities().First();
      Assert.IsTrue(emp.EntityAspect.EntityKey == sameEmp.EntityAspect.EntityKey, "should have the same key");
      sameEmp.EntityAspect.Delete();
      Assert.IsTrue(sameEmp.EntityAspect.EntityState.IsDeleted());
      var sr2 = await em2.SaveChanges();
      Assert.IsTrue(sr2.Entities.First() == sameEmp, "should still be the same emp");
      Assert.IsTrue(sameEmp.EntityAspect.EntityState.IsDetached());
      Assert.IsTrue(em2.GetEntities().Count() == 0, "should be no entities");

    }