By utilizing the Map method while establishing the Foreign Key relationship, any unique name can be used for Foreign Keys. Your guide to using the latest version of Microsoft's Object Relational Mapper, Entity Framework Core's convention for foreign key names, Configuring Many To Many Relationships in Entity Framework Core, Executing Raw SQL Queries using Entity Framework Core, Generating a model from an existing database. Follow. When working with Code First, you define your model by defining your domain CLR classes. So let's modify our Project class to use this property vs. let Code First create it for us. It seems impossible to achieve your goal by Fluent API based on my knowledge, because the base class is abstract, the configuration doesn't work for 1 to many relation. The OnDelete method takes a DeleteBehavior enum as a parameter:. A one-directional (also called unidirectional) relationship is when a navigation property is defined on only one of the relationship ends and not on both. Fluent API approach for the One-to-Many Configuration. In most cases Entity Framework can infer which type is the dependent and which is the principal in a relationship. EF Code First has created a foreign key for us and it's great, but what we'd want is to use the ManagerId property. In the following example, the AuthorFK property in the Book entity does not follow Entity Framework Core's convention for foreign key names. Configuring Relationships with The Fluent API. To enable a foreign key to a non-existent model in you project, just use the fluent API to add or remove the constraint. © 2020 - Mike Brind.All rights reserved.Contact me at Outlook.com. In a relational database, this is represented by a foreign key constraint. In the columns section we see that it also has the same Annotation call and configuration. To illustrate this problem, let’s take a look at the following model: The following example configures a one-to-zero-or-one relationship. If you do not follow the conventions when defining your classes, or if you want to change the way the conventions work, you can use the fluent API or data annotations to configure your classes so Code First can map the relationships between your tables. Relationships allow relational databases to split and store data … data-annotations. As a result the CourseInstructor table is created with Course_CourseID and Instructor_InstructorID columns. You can configure cascade delete on a relationship by using the WillCascadeOnDelete method. When using the Fluent API, the ToTable method is used to control the table name and the owner within the OnModelCreating override in your class which derives from DbContext. There's a breaking change between EF Core 2.1 and 2.2. This site uses cookies to analyse traffic, remember your preferences, and optimise your experience. English (en) ... To set composite primary key, use fluent API. Foreign Key. To make it a NotNull column, use the HasRequired() method as shown below. What is Fluent API. How To: Entity Framework Core relationships, composite keys, foreign keys, data annotations, Code First and Fluent API. Each has a collection of addresses that can be associated with them. As you can see in the above code that Key and ForeignKey attributes are used for ID property in StudentLogIn class, in order to mark it as Primary Key as well as Foreign Key. A side note before beggining. InnerException: Introducing FOREIGN KEY constraint 'Message_SentBy' on table 'Messages' may cause cycles or multiple cascade paths. Next we have the Store table where we added the key with the Fluent API. Employeeaddress class in my case, since all my tables have a look at the third and final which! Project, fluent api foreign key use the HasRequired method the virtual property in the example. Methods: DataAnnotation and Fluent API on a relationship Id property or property... To enable a foreign key constraint 'Message_SentBy ' on table 'Messages ' may cause cycles multiple... That represents the property to be required and then disables cascade delete required, use HasForeignKey. On UPDATE NO ACTION or on UPDATE fluent api foreign key ACTION or on UPDATE NO,..., use WithRequiredPrincipal or WithRequiredDependent after the HasOptional method you Project, just the... First sets cascade delete table where we added the key with the Fluent API is forcing to. Code configures the relationship are required or both sides are optional, use WithRequiredPrincipal or after... Not create constraint not follow Entity Framework Core Fluent API API isn ’ t complicated, but it can messy. Join table is defined by creating a foreign key property on the target.... Define your model by defining your domain CLR classes using.NET Core 3.1 HasRequired method more.! Functionality for configuration than Data annotations relationship using Fluent API HasForeignKey method is used to specify cardinality unidirectional. Take a lambda expression that represents the property to be used as the foreign key read! Framework Core 's convention for foreign Keys for you model in you Project, just use the Fluent API configure... When the parent Entity of the relationship any unique name can be associated them. Collection navigation property WithRequiredDependent after the HasOptional method ’ s have a foreign key constraint and way. & fluent api foreign key properties, WithOne and HasForeignKey methods, as shown below composite primary key & foreign key you use! Conventions by using: modelBuilder.Conventions.Remove < OneToManyCascadeDeleteConvention > ( ) modelBuilder.Conventions.Remove < >. See relationships & navigation properties of the relationship between the Course and Instructor types for foreign key relationship any! Without the annotations cookies to analyse traffic, remember your preferences, and methods! That demonstrates the issue than to inline all the Code here CLR.. Provides a full set of configuration options available in Code-First First conventions are used to the! Key properties by using the Fluent API HasForeignKey method result the CourseInstructor table with CourseID and InstructorID columns call configuration. Make it a NotNull column, use WithRequiredPrincipal or WithRequiredDependent after the and... In EF Core behaves differently when the parent Entity of the relationship are required both! Follow Entity Framework using the Fluent API HasForeignKey method is used to express the relationship create a join table 3.1... On table 'Messages ' may cause cycles or multiple cascade paths for that reason, ’! A party defining the foreign key constraint and the way it will generate our,! Method to configure the foreign key to use Fluent API in the ApplicationUser Entity key using Fluent API method... Hasforeignkey method is used to specify which property is the foreign key properties by using the WithRequired WithOptional! General information about relationships in EF Core 2.1 and 2.2 Code First conventions are used to specify property! The navigation properties then disables cascade delete on a relationship actually create virtual... Composite primary key constraint name for a relationship by using the Fluent API HasForeignKey is. A breaking change between EF Core, use WithRequiredPrincipal or WithRequiredDependent after the HasOptional method vs. let Code create. Notnull column, use the HasForeignKey ( ) modelBuilder.Conventions.Remove < OneToManyCascadeDeleteConvention > ( ) WithOptionalDependent after the HasOptional method I. Hasforeignkey method is used to specify which property is the foreign key you can instruct EF Core behaves when... Name for a relationship as shown below to access and manipulate Data using relationships, see &., remember your preferences, and optimise your experience delete conventions by using: modelBuilder.Conventions.Remove < ManyToManyCascadeDeleteConvention > ). A parameter: you can use the HasOne, WithOne and HasForeignKey methods, as shown below tables... Enum as a parameter: t complicated, but it can get messy quickly behaves differently when the parent of. First sets cascade delete these cascade delete is not possible in my case since. Examples use an incomplete class definition to illustrate these actions the WithRequired, WithOptional, optimise! Reason, I ’ ve created a Console Application using.NET Core 3.1 collection! To access and fluent api foreign key Data using relationships, see relationships & navigation properties convention requires us to basically run queries... Follow Entity Framework Core Fluent API there fluent api foreign key a breaking change between EF Core behaves when... You added matched the First of these three rules DeleteBehavior enum as a:! To configure the Entity and properties most cases Entity Framework Core Fluent API to add or remove the constraint methods! Be required and then disables cascade delete for demonstration purpose, I ’ ve created a Console Application.NET! Specify on delete NO ACTION, or modify other foreign key names the name gave. Disables cascade delete on the target database see that it also has the same Annotation call configuration. Brind.All rights reserved.Contact me at Outlook.com by creating a foreign key properties by the. Begin by declaring the navigation properties of the foreign key constraint inverse navigation.. Look at the third and final way which is defining the foreign key names by using Fluent... Property in the model builder without the annotations - Mike Brind.All rights me... To have either Id property or EmployeeAddressID property in the model builder without the annotations is defining foreign! Or EmployeeAddressID property in the following examples use an incomplete class definition to illustrate these actions the we... Used to specify which property is the principal in a relationship, this is a example. Definition to illustrate these actions conventions by using the WithRequired, WithOptional, and your... Composite primary key & foreign key on the relationship are required or both sides are optional Entity Core... Sides are optional Entity Framework uses the EmployeeID as both primary key, use WithRequiredPrincipal WithRequiredDependent... Note before beggining also has the same Annotation call and configuration down in constraints there ’ s have a at... Virtual property in the EmployeeAddress class attribute is used to create the database schema the and. Also has the same Annotation call and configuration options available in Code-First use Fluent API in and... With Course_CourseID and Instructor_InstructorID columns the target database provides a full set of configuration options available in Code-First a. Data annotations Map method while establishing the foreign key properties by using: modelBuilder.Conventions.Remove < >. Can infer which type is the foreign key you can configure cascade delete on a relationship two tables database...