background preloader


Facebook Twitter

A LINQ extension method to calculate a running total - The other day I needed to calculate a running balance based on a series of either debit or credit transactions.

A LINQ extension method to calculate a running total -

So each line item contains a balance column that is the carried forward balance plus the sum of debits and credits up until the current line item. After some playing around I came up with a simple LINQ expression to do the job. It is also a nice illustration of how LINQ expression trees enable you to create more elegant solutions. Lets start by create a simple object: public class LineItem{ public decimal Debit { get; set; } public decimal Credit { get; set; } public decimal Balance { get; set; }} Rollup Extension Method: Create Running Totals using LINQ to Objects - Eric White's Blog.

Recently, I had need for a new extension method for IEnumerable<T>, which I call "Rollup".

Rollup Extension Method: Create Running Totals using LINQ to Objects - Eric White's Blog

This extension method is sort of a cross between the Select and Aggregate extension methods. Like Select, when using this extension method you write a lambda expression to project the new value in a new collection. Unlike Select, in the projection lambda expression, you are passed the projected value for the immediately preceding element. The previous value for the first element in the projected collection is a seed value that you pass to the Rollup extension method. SQL Joins with C# LINQ. Posted By : Shailendra Chauhan, 18 Oct 2012 Updated On : 25 Nov 2013 Keywords : linq join on multiple conditions,c# join example, linq inner join with multiple conditions, linq left outer join, linq left join, linq cross join, linq right join, linq group join There are Different Types of SQL Joins which are used to query data from more than one tables.

SQL Joins with C# LINQ

SQL Joins with C# LINQ. RiggsHill Software. There are two flavors of serialization you can use on Framework entities: good ol' XML serialization and the DataContract serialization.

RiggsHill Software

XML serialization is pretty straightforward - it serializes the object it's given. But it does not walk references (I'm talking foreign keys here) or collections. whereas the DataContract serializer does handle the references and keeps track of what objects have been serialized and what hasn't. If you're going to use XSLT on the serialization, I'm not sure at this point which one is better - they're probably equal but time will tell. Unfortunately you can't directly serialize the entire ObjectContext, only collections or individual objects can be serialized. But this isn't as bad as it sounds as usually you'll want to start at some 'master object' in a collection and serialize it and all it references, so the inability to directly serialize the Context is not a big loss. MainModule.vb. Managing BLOBs using SQL Server FileStream via EF and WCF streaming. Public Interface IDocumentService <OperationContract()> Sub SaveDocument(documentInfo As DocumentInfo) <OperationContract()> Function GetDocumentKeysByFullText(searchCondition As String) As List(Of DocumentKeys)

Managing BLOBs using SQL Server FileStream via EF and WCF streaming

EF Code First Extras. Tracing and Caching for Entity Framework available on MSDN Code Gallery - Jaroslaw Kowalski. We have just released a sample that shows how to extend Entity Framework in interesting ways by plugging into ADO.NET provider interface.

Tracing and Caching for Entity Framework available on MSDN Code Gallery - Jaroslaw Kowalski

The sample provides two extensions: EFTracingProvider – which adds the ability to log all SQL commands that are executed (similar to LINQ to SQL’s DataContext.LogEFCachingProvider – which adds transparent query results cache to EF The sample comes with implementation of distributed cache which uses Velocity CTP 3 as well as an adapter for ASP.NET and simple in-memory cache implementation. Because the sample is quite large and uses many advanced techniques, it’s impossible to fully explain it all in one blog post. In this first post I’ll briefly explain the idea of wrapper providers and describe the new the APIs exposed by EFTracingProvider and EFCachingProvider.

Provider Wrapers. Tip 14 - How to cache Entity Framework Reference Data - Meta-Me. Scenario: In order to make applications perform it makes a lot of sense to cache commonly used reference data.

Tip 14 - How to cache Entity Framework Reference Data - Meta-Me

Good examples of reference data include things like States, Countries, Departments etc. Generally you want to have this data readily at hand, so you can populate dropdown boxes etc. A good example where caching reference data might be handy is a web page for signing up new customers, part of the form collects the customers address, including their State. In this example you need the reference data for two things: Exposing the ORM Cache. Related Content Browse this Topic: Queue on Reddit Exposing the ORM Cache Familiarity with ORM caching issues can help prevent performance problems and bugs.

Exposing the ORM Cache

In the early 1990s, when object-oriented languages emerged into the mainstream of software development, a noticeable surge in productivity occurred as developers saw new and better ways to create software programs. Complex problems sometimes demand complex solutions, and ORM software is no exception. Caching is generally recognized as being vital to performance optimization. Caching can be one of the most technologically advanced components of an ORM implementation, thus representing a critical balance point for any application that uses the implementation. Objects and Identity First and foremost developers must acknowledge the nature of objects and how they are used in object-oriented languages. An object graph, by definition, implies that there may be multiple paths leading to the same object. Доступ к данным - Second-Level Caching in the Entity Framework and AppFabric. Tracing and Caching Provider Wrappers for Entity Framework in C# for Visual Studio 2010.

Repository, Specification, Unit of Work, Persistence Ignorance POCO with Microsoft ADO.NET Entity Framework 4.0 Beta 2 « KITCHAIYONG.NET. Preface As of preparing this writing and the source codes, I was using the .NET Framework 4.0 Beta 1, Visual Studio 2010 Beta 1 and ADO.NET Entity Framework Feature CTP 1.

Repository, Specification, Unit of Work, Persistence Ignorance POCO with Microsoft ADO.NET Entity Framework 4.0 Beta 2 « KITCHAIYONG.NET

However, the .NET Framework 4.0 Beta 2 and Visual Studio 2010 Beta 2 made their debut on 21 October 2009. I decided to upgrade the projects to this latest beta 2 version. So, the requirements to run the sample projects that come with this post has changed to .NET Framework 4.0 Beta 2 and Visual Studio 2010 Beta 2 which you can download them at this address, I am using the Visual Studio 2010 Ultimate Beta 2 which is downloadable as ISO file at However, the Entity Framework Feature Community Technology Preview 2 is not yet available while I have already finished my code development on Visual Studio 2010 Beta 2.

It is only available on 04 November 2009 which is downloadable at To learn more about the EF CTP Preview 2, please follow So you can run the sample projects without the EF CTP Preview 2. .NET Junkie - Faking your LINQ provider part 1. Friday, someone at Stackoverflow asked how to hide LINQ enabled persistence frameworks behind an abstraction (the repository pattern).

.NET Junkie - Faking your LINQ provider part 1

I pointed him to a question on Stackoverflow that I answered a few days earlier in what I explained how to allow your LINQ to SQL project to be unit testable. Friday’s question however, was about being able to easily change the O/RM later on, and specifically with multiple data stores / databases involved. Let me start by saying that due to the current difference in behavior and quality between both open source and commercial LINQ provider implementations, it is hard to completely abstract away such implementation, while still allowing to use LINQ to Expression queries that are effectively translated to database queries. For the project I'm currently working on, I use LINQ to SQL as O/RM tool and I was faced with the problem of unit testing. I wrote this answer on Stackoverflow with the experience gained on this project.

Unit of Work. mvc 3 - MVC, EF - DataContext singleton instance Per-Web-Request in Unity. Generic Repository Pattern - Entity Framework, ASP.NET MVC and Unit Testing Triangle. IMPORTANT NOTE: I have a new blog post about Generic Repository implementation for Entity Framework. Please check it out instead of this one: Clean, Better, and Sexier Generic Repository Implementation for Entity Framework NOTE:Entity Framework DbContext Generic Repository Implementation Is Now On Nuget and GitHub: DRY: Don’t repeat yourself which is a principle of software development aimed at reducing repetition of information of all kinds, especially useful in multi-tier architectures.

That’s what Wikipedia says. In my words, if you are writing the same code twice, follow these steps: О разработке ПО и эффективности: Code First Migrations + Entity Framework 4.3 Beta 1. Mapping private/protected/… properties in Entity Framework 4.x Code First  Mapping private/protected/... properties in Entity Framework 4.x Code First More than a year ago I was blogging about how to map private/protected/... properties in Code First CTP4 for the time being. Well it a long time and a lot of changed. Advanced Data - Programming ASP.NET MVC 4 Web Applications. Testability and Entity Framework 4.0. Scott Allen Published: May 2010 Introduction This white paper describes and demonstrates how to write testable code with the ADO.NET Entity Framework 4.0 and Visual Studio 2010. This paper does not try to focus on a specific testing methodology, like test-driven design (TDD) or behavior-driven design (BDD). Mvc & jQuery CMS - The Repository Pattern with EF code first & Dependeny Injection in ASP.NET MVC3.

Introduction. Entity Framework POCO (EF4): Generic Repository and Unit of Work Prototype. In my previous post I demonstrated how to create a simple mapping using the latest EF4 CTP. In this post I will look at how I can customize some infrastructure code in an attempt to align EF POCO “Code Only” with existing patterns, while potentially increasing reuse and testability. A popular pattern for ORM data access is the Repository pattern. POCO in the Entity Framework : Part 3 – Change Tracking with POCO - ADO.NET team blog. The information in this post is out of date. Implementing the Repository and Unit of Work Patterns in an ASP.NET MVC Application (9 of 10) ObjectContext Undo, Cancel? Developing web apps using ASP.NET MVC 3, Razor and EF Code First - Part 1 - Shiju Varghese's Blog. EF Feature CTP5: Pluggable Conventions - ADO.NET team blog.