Solved Entity framework migration C# GUID foreign keys

We can see that EF Core utilized the Discriminator column, even though there is no explicit mention of it in our database model. Executing the database update command will apply our migrations up to the latest. There are multiple ways to insert data into our database, but it’s a good idea to use the data seed mechanism of EF Core for demos and necessary look-up values.

EF API maps each entity to a table and each property of an entity to a column in the database. In this scenario, the same context class is used to retrieve and save entities. When an entity has the property of another type of entity property, it is called reference navigation property. It points to a single entity but represents the multiplicity of one.

POCO Entities (Plain Old CLR Objects)

However, not all EF6 features are currently implemented in EF Core. An ORM Framework like Entity Framework or EF Core can do all of the above for us and saves a lot of time if we provide the necessary required information to the ORM Framework. The ORM Framework sits between our application code and the Database. It eliminates the need for most custom data-access codes we usually write without an ORM. Entity Framework (EF) Core is an ORM (Object-Relational Mapper) Framework for data access in .NET Core.

• Entity Framework is an open-source ORM framework for .NET applications supported by Microsoft.
• EF API will create a ForeignKey column in the table for the navigation properties that points to a PrimaryKey of another table in the database.
• This approach first targets a database that does not exist and then creates it.

In the database, EF API will create a ForeignKey Grade_GradeId in the Students table, as shown below. Entity Framework is an Object/Relational Mapping (O/RM) framework. It is an enhancement to ADO.NET that gives developers an automated mechanism for accessing & storing the data in the database. In the video, I referred to POCOs as “Plain Old C# Objects”, though they’re sometimes known as “Plain Old CLR Objects”.

EF Core Database Providers

Here, select the “EF Designer from database” option as we are going to use the Entity Framework Database First Approach. This list is created based on the most notable features and also from frequently asked questions about Entity Framework. The application is using Entity Framework version 6.1.3 and .NET Framework 4.5. 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.

It eliminates the majority of the data-access code that developers must routinely write. Additionally, we can ask Rider to diagram our database tables, showing the relationships that we modeled during the code-first design phase of this tutorial. As per the above figure, Entity Framework fits between the business entities (Domain Classes) and the database. It saves the data in the business properties entities and also retrieves the data from the database and converts it into the business entity’s object automatically. To solve this problem for specific scenarios, you can use eager loading in EF Core.

The outer query, i.e., the entitiesQuery, executes just once to load all the author records together with the related book data. Instead of making round trips to the database, the two foreach loops work on the available data in the memory. To solve this problem, you should fetch the related data in advance (using eager loading) as part of the “1” query. In other words, you should include the book data in your initial query for the author data, as shown in the code snippet given below. The following code snippet illustrates how you can use async code to update an entity in the database using EF Core.

Entity Framework allows you to develop and maintain data-oriented apps with less code than traditional applications. Great, now that we have built our entities and relationships, let’s add them to our DbContext instance, which we’ll call EntertainmentDbContext. We’ll also what is entity framework want to define our database connection string for demo purposes. In the code snippet that follows, we’ll create a custom data context class by extending the DbContext class of EF Core library. When you’re quering data in EF Core, use IQueryable instead of IEnumerable.