Its instances should therefore be disposed of as soon as they’re not needed anymore. If you’re coming from an NHibernate background, the way Entity Framework persists changes to the database is one of the major differences between EF and NHibernate. For those coming from an NHibernate background, this is the equivalent of having to manage multiple SessionFactory instances. If a property on the Config graph implements an interface then a registration is made with Autofac with the settings deserialized onto the service instance. Saves all changes made using this context to the underlying database.
- NHibernate users will be very familiar with this approach as the ambient context pattern is the predominant approach used in the NHibernate world to manage NH’s Session (NHibernate’s equivalent to EF’s DbContext).
- Lazy loading is great for scenarios where you don’t need the related entities immediately, but it can result in more database queries overall if not used judiciously.
- Chances are it would simplify your code and offer better performance by not having the additional overhead that EF introduces to support its additional functionalities.
NHibernate users will be very familiar with this approach as the ambient context pattern is the predominant approach used in the NHibernate world to manage NH’s Session (NHibernate’s equivalent to EF’s DbContext). NHibernate even comes with built-in support for this pattern, which it calls what is entity framework contextual sessions. In practice, and unless you actually need a distributed transaction, you should avoid using TransactionScope. TransactionScope, and distributed transactions in general, are not necessary for most applications and tend to introduce more problems than they solve.
Async support
Learn Entity Framework DB-First, Code-First and EF Core step by step. While using this site, you agree to have read and accepted our terms
of use and privacy policy. Learn how to create the first simple EF Core console application in the next chapter. Joydip Kanjilal is a Microsoft MVP in ASP.NET, as well as a speaker and author of several books and articles. He has more than 20 years of experience in IT including more than 16 years in Microsoft .NET and related technologies.
To create the class file names ” and inherit the class from the DbContext class as shown below, you wish you could give any name for DbContext class here. This is an advanced feature that I would expect most applications to never need. Tread carefully when using this as it can create tricky issues and quickly lead to a maintenance nightmare. Those DbContext instances are created lazily and the DbContextScope keeps track of them to ensure that only one instance of any given DbContext type is ever created within its scope. Remember that DbContext (just like Session in NHibernate) isn’t thread-safe.
DbContextOptionsBuilder
Model-First is an approach to development with Entity Framework where you begin by designing your database schema in a visual designer included with Visual Studio. After creating your data model, EF generates corresponding database and classes for you. You can configure a separate DbContext instance to access the read replica of your database, and use that DbContext for read-only queries. The DbContext is the part of the EntityFramework.dll assembly that is installed individually at the NuGet package manager. Entity Framework DbContext is the class where it is the bridge between the entity or types and the database.
In the above example, when we have updated the existing student entity. Once we update at least one property, the entity will be moved to the Modified state and when we call the SaveChanges method, the context object will generate and execute the following UPDATE SQL Script. Once the SaveChanges method execution is completed successfully, it will move the Entity state from Modified to Unchanged state. Now, we need to update one existing entity i.e. we need to update the First name and Last name of the newly created student i.e. the student whose student id is 5.
Note that the outer foreach loop will fetch all authors using one query. The inner foreach that fetches the books represents the “N” in your N+1 problem, because the inner foreach will be executed N times. Migrations allow you to evolve your database schema over time while preserving existing data. The Code First approach is flexible and easy to control, which makes it an excellent choice for software that needs to be robust, but also easy to update and maintain over long periods of development time.
