A LINQ extension method to calculate a running total - blog.dee4star.com. The other day I needed to calculate a running balance based on a series of either debit or credit transactions.
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. 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".
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. 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.
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.
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) <OperationContract()> Function GetDocument(ID As Guid) As System.IO.Stream End Interface.
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.
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. 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.
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. 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.
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. Caching Levels Transactional Cache. 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.
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. .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).
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. Asp.net mvc 3 - MVC, EF - DataContext singleton instance Per-Web-Request in Unity.
I have a MVC 3 web application, where I am using the Entity Framework for the data access. Furthermore, I have made a simple use of the repository pattern, where e.g. all Product related stuff is handled in the "ProductRepository" and all User related stuff is handled in the "UserRepository". Thus, I am using the UNITY container, to make a singleton instance of the DataContext, which I inject into each of the repositories. A quick search on Google, and everyone recommends you to NOT use a singleton instance of the DataContext, as it might give you some memory leaks in the future. So, inspired by this post, making a singleton instance of the DataContext for each web request is the answer (please correct me if I am wrong!) 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: Step back.
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. Open Feedback Publishing System (OFPS) is now retired.
Thank you to the authors and commenters who participated in the program. OFPS was an O'Reilly experiment that demonstrated the benefits of bridging the gap between private manuscripts and public blogs. Readers gained access to in-progress O'Reilly manuscripts and were able to communicate suggestions with the authors, follow others' comments, and directly participate in the development of new books. 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. POCO in the Entity Framework : Part 3 – Change Tracking with POCO - ADO.NET team blog. 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.