February, 2010

Article was updated on 3/4/2010

This article can be useful for programmers who want to develop cross-database applications and use the canonical functions.

Entity Framework Canonical Functions are a set of functions, which are supported by all Entity Framework providers. These canonical functions are translated to the corresponding data source functionality for the provider.

The tables below contain information about these functions supported by the Devart products.
Functions supported by the following DBMS: MySQL, PostgreSQL, Oracle, SQLite, SQL Server 2005, and SQL
Server 2008 are marked in green.

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Introduction

In this article we consider how to build Entity Framework models using PostGIS objects in Entity Developer. PostGIS is a popular spatial extension for PostgreSQL that gives one an opportunity to work with geographic objects. To create and use such models we will:

• use a .NET wrapper for PostGIS (SharpMap)
• build a new Entity C# code generation template in order to enable geometry types support
• write some code dealing with change tracking

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Go to devart.uservoice.com and share your ideas about new features you want to see in Entity Developer. There you may vote for features that are already in our roadmap, and they will have higher priority in our plans, or you may suggest your own features, and if they will get enough votes, we will include them to the roadmap. Your opinion helps us to make Entity Developer better and more useful for you.

Currently Entity Developer roadmap includes the following features:
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Entity Framework

In this article we consider a short description of the Entity Framework and LINQ to SQL transactional models. There are also some simple code listings illustrating different aspects of the transactional model.

A transaction is a series of operations performed as a single unit of work. Entity Framework transactions are a part of its internal architecture. The SaveChanges method operates within a transaction and saves results of the work. It is designed to ensure data integrity. The common reason of integrity problems is a Concurrency violation, which can be raised during the saving process. Concurrency violation occurs an OptimisticConcurrencyException in this case. To resolve this conflict you have to call the Refresh method with the StoreWins or ClientWins value, and after that call SaveChanges again. But be aware, that the Refresh with the ClientWins option can be a source of problem too. It rewrites all changes made to the data after context query execution.
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