How do you map a one-to-one relationship in Entity Framework?

We can configure one-to-one relation between Employee and EmployeeDetail using Fluent API by the following code in a model class:

1. protected override void OnModelCreating(DbModelBuildermodelBuilder)
2. {
3. modelBuilder. Entity < Customer > (). HasKey(p => p.
4. modelBuilder. Entity < Customer > (). HasOptional(e => e.
5. }

How do you add relationships in Entity Framework?

According to Relationships/Associations with the EF Designer, the steps to create a foreign key association are:

1. Right-click an empty area of the design surface, point to Add New, and select Association….
2. Fill in the settings for the association in the Add Association dialog.

What is mapping in Entity Framework?

It is a tool to access the database. More accurately, it’s classified as an Object/Relational Mapper (ORM) which means it maps data in a relational database into objects of our applications. Entity Framework. It is a tool to access the database.

How does Entity Framework define relationships?

Fully defined relationships

1. If a pair of navigation properties is found between two types, then they will be configured as inverse navigation properties of the same relationship.
2. If the dependent entity contains a property with a name matching one of these patterns then it will be configured as the foreign key:

What is OnModelCreating in Entity Framework?

The DbContext class has a method called OnModelCreating that takes an instance of ModelBuilder as a parameter. This method is called by the framework when your context is first created to build the model and its mappings in memory.

What is an example of a one-to-one relationship?

A one-to-one relationship exists when each row in one table has only one related row in a second table. For example, a business might decide to assign one office to exactly one employee. Thus, one employee can have only one office. The same business might also decide that a department can have only one manager.

How do I install Entity Framework?

Entity Framework When to Use Include

1. Lazy loading is the process whereby an entity or collection of entities is automatically loaded from the database.
2. Lazy loading is enabled by default in Entity Framework, and we can mark specific navigation properties or even whole entities as lazy by making them virtual.

What is DbContext in Entity Framework?

DbContext is an important class in Entity Framework API. It is a bridge between your domain or entity classes and the database. DbContext is the primary class that is responsible for interacting with the database. Querying: Converts LINQ-to-Entities queries to SQL query and sends them to the database.

What is a zero to one relationship?

A zero-or-one-to-many means that the object on the “many” side of the relationship can exist even if not related to any object on the “one” side. In the factory/product example, this would mean that a product can exists even if no factory produces it.

What is fluent API in Entity Framework?

Entity Framework Fluent API is used to configure domain classes to override conventions. EF Fluent API is based on a Fluent API design pattern (a.k.a Fluent Interface) where the result is formulated by method chaining. You can use Data Annotation attributes and Fluent API at the same time.

What is scaffold DbContext?

Reverse engineering is the process of scaffolding entity type classes and a DbContext class based on a database schema. It can be performed using the Scaffold-DbContext command of the EF Core Package Manager Console (PMC) tools or the dotnet ef dbcontext scaffold command of the . NET Command-line Interface (CLI) tools.

What is a dbset in Entity Framework?

DbSet in Entity Framework The DbSet class in Entity Framework represents an entity set that can be used for the database CRUD Operations i.e. create, read, update, and delete operations. The context class should derive from DbContext class and must include the DbSet type properties for the entities which map to database tables and views.

What is an entity in Entity Framework?

An entity in Entity Framework is a class that maps to a database table. This class must be included as a DbSet type property in the DbContext class. EF API maps each entity to a table and each property of an entity to a column in the database.

What is Entity Framework fluent API?

Entity Framework – Fluent API. Fluent API is an advanced way of specifying model configuration that covers everything that data annotations can do in addition to some more advanced configuration not possible with data annotations.

What is migration EF Core?

The migrations feature in EF Core provides a way to incrementally update the database schema to keep it in sync with the application’s data model while preserving existing data in the database. Migrations includes command-line tools and APIs that help with the following tasks: Create a migration.