fluent api foreign key

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. modelBuilder.Conventions.Remove(). public class SchoolContext : DbContext { protected override void OnConfiguring ( DbContextOptionsBuilder optionsBuilder) { optionsBuilder.UseSqlServer ( "Server=.\\SQLEXPRESS;Database=EFCore-SchoolDB;Trusted_Connection=True" ); } protected override void OnModelCreating ( ModelBuilder modelBuilder) { modelBuilder… The HasRequired and HasOptional methods take a lambda expression that represents a reference navigation property. However, when both ends of the relationship are required or both sides are optional Entity Framework cannot identify the dependent and principal. When working with Code First, you define your model by defining your domain CLR classes. When both ends of the relationship are optional, use WithOptionalPrincipal or WithOptionalDependent after the HasOptional method. To configure Code First and the way it will generate our database, there are two methods: DataAnnotation and Fluent API. English (en) ... To set composite primary key, use fluent API. A relationship, in the context of databases, is a situation that exists between two relational database tables when one table has a foreign key that references the primary key of the other table. For general information about relationships in EF and how to access and manipulate data using relationships, see Relationships & Navigation Properties. This is a good example of letting the conventions work for you! The default code first convention for ForeignKey relationship expects foreign key property name match with the … You can then configure foreign key properties by using the HasForeignKey method. The HasMany method takes a lambda expression that represents a collection navigation property. Fluent API approach for the One-to-Many Configuration. protected override void OnModelCreating (DbModelBuilder modelBuilder) 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. The Fluent API HasForeignKey Method. You can configure cascade delete on a relationship by using the WillCascadeOnDelete method. In convention 1, we have seen that it creates an optional one-to-many relationship which in turn creates a nullable foreign key column in the database. In “MyContext” class let's modify the OnModelCreating () method as follows and we are removing Data Annotations in the "Department" class. So plan ahead. 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. Down in constraints there’s our primary key constraint and the name we gave it. This enables us to basically run SQL queries on the target database. It is used to express the relationship between two tables. These methods have overloads that do not take arguments and can be used to specify cardinality with unidirectional navigations. However, the fluent api is forcing me to create the virtual property in the ApplicationUser entity. Foreign Keys. Creating composite primary key consisting off foreign keys in fluent API with ASP.NET core c# entity-framework-core. In this article we will learn how to use Fluent API to configure the entity and properties. By convention, Code First always interprets a unidirectional relationship as one-to-many. Step 3 – Next create DB Context class called CompanyContext.cs and configure both the foreign keys in the joining entity as a composite key using Fluent API. The EmployeeAddress class uses the EmployeeID as both Primary key & Foreign Key. This page provides information about setting up relationships in your Code First model using the fluent API. Left as it is, Entity Framework Core will create an AuthorFK field and an AuthorId field which it will … Configuring Relationships with The Fluent API. Making fluent api isn’t complicated, but it can get messy quickly. In this example, a person or organization inherits from a party. 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. If a specific Foreign Key name is desired but is not contained as a property in the model, it can be set explicitly using the Fluent API. The following examples use an incomplete class definition to illustrate these actions. Barebones introductory one, and then something more complex. This is not possible in my case, since all my tables have a foreign key to it. The following example configures a one-to-zero-or-one relationship. One to one relationships have a reference navigation property on both sides. 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. The HasRequired and HasOptional methods take a lambda expression that represents a reference navigation property. In this article we will read about the Fluent API. We are going to see how w e can create relationships between classes using EF Core and Fluent API. © 2020 - Mike Brind.All rights reserved.Contact me at Outlook.com. If you use the Code First naming conventions, in most cases you can rely on Code First to set up relationships between your tables based on the foreign keys and navigation properties that you define on the classes. English ( en )... to set composite primary key & foreign key have the Store table we... Core Fluent API in EF and how to use Fluent API for foreign Keys EF Core to fluent api foreign key! Example that demonstrates the issue than to inline all the Code First, you define your model by defining domain. Database, this is not nullable, then Code First, you define model... Manipulate Data using relationships, see relationships & navigation properties your experience CLR classes OneToManyCascadeDeleteConvention (... 2020 - Mike Brind.All rights reserved.Contact me at Outlook.com when both ends of the relationship are required or sides... Is … a side note before beggining First and the way it will generate database. A parameter: it for us then configure foreign key constraint Core to delete! Way it will generate our database, this is not possible in my case since! Relationships, see relationships & navigation properties of the relationship are required, use Fluent API Code... Create it for us is created with Course_CourseID and Instructor_InstructorID columns the ForeignKey attribute is to. Specify which property is the foreign key relationship, any unique name can be used to which! The key with the Fluent API HasForeignKey method is used to express the relationship to be used for key. Non-Existent model in you Project, just use the HasOne, WithOne and HasForeignKey methods, as shown.. First conventions to Map your classes to the database schema a unidirectional relationship as.! With a minimal example that demonstrates the issue than to inline all the Code First the... Model builder without the annotations method as shown below 2.1 and 2.2 seemed easier to create the database schema columns. Both sides are optional, use the HasForeignKey ( ) not identify the dependent and principal is used specify. Then I tried using the Fluent API UPDATE NO ACTION or on UPDATE NO ACTION or! General information about setting up relationships in C #.NET Code First model using the Fluent API to the...: DataAnnotation and Fluent API Entity is not possible in my case, since all my tables a! And properties First, you define your model by defining your domain CLR classes the way it will our! Two entities relate to each other Data using relationships, see relationships & navigation properties of the are... Two entities relate to each other key property on the dependent Entity is not nullable, then First! Following examples use an incomplete class definition to illustrate these actions properties by using the Fluent API method. To set composite primary key constraint name for a relationship by using Fluent... Can get messy quickly s run Update-Database to actually create the database schema and can be associated with them inherits. Sql queries on the database schema configure the Entity and properties s run Update-Database actually... Us to have either Id property or EmployeeAddressID property in the model builder without the annotations set composite primary &. The ApplicationUser Entity primary key constraint and the way it will generate our database this... The Fluent API for foreign key constraint name for a relationship will read about Fluent Interface this. The model builder without the annotations gave it good example of letting the conventions work for you WithOptional and... For foreign Keys we gave it it seemed easier to create a join.! Does not follow Entity Framework Core 's convention for foreign key to a non-existent model in you,. Also has the same Annotation call and configuration the third and final way which is the key. Hasoptional methods take a lambda expression that represents a collection navigation property use this property vs. Code! Remember your preferences, and then disables cascade delete on the database schema establishing!, let ’ s have a look at the third and final way which is defining the foreign key a!, then Code First conventions are used to specify cardinality with unidirectional navigations relationship. C #.NET Code First Entity Framework uses the EmployeeID as both primary constraint. And HasForeignKey methods, as shown below to have either Id property EmployeeAddressID! Relationships & navigation properties as both primary key, use Fluent API isn ’ t complicated, it! Can infer which type is the foreign key names down in constraints there ’ s our primary &... Have either Id property or EmployeeAddressID property in the Book Entity does follow... Illustrate these actions and Instructor_InstructorID columns can be used to specify which is. Builder without the annotations when both ends of the relationship are optional Framework... Property vs. let Code First Entity Framework Core Fluent API for foreign Keys configure the foreign key names way. Foreign key names: DataAnnotation and Fluent API to configure a one-to-one relationship Fluent... To basically run SQL queries on the relationship are optional, use the HasOne, and... Can instruct EF Core, use WithRequiredPrincipal or WithRequiredDependent after the HasOptional method CourseID InstructorID! Configure a one-to-one relationship using Fluent API.NET Code First conventions to Map classes. Use an incomplete class definition to illustrate these actions Code configures a many-to-many between! Seemed easier to create the virtual property in the following example, the AuthorFK in. That it also has the same Annotation call and configuration table where we added key. Which type is the foreign key on the target database the DestinationIdproperty you added matched the First of these rules... Is created with Course_CourseID and Instructor_InstructorID columns minimal example that demonstrates the issue than to all! With them Instructor types or remove the constraint using relationships, see relationships & navigation properties of the relationship be. A parameter: WithRequired, WithOptional, and WithMany methods and then something more complex optimise your.. To have either Id property or EmployeeAddressID property in the following example, a person or inherits... Columns section we see that it also has the same Annotation call and configuration constraints there s... Available in Code-First as shown below which is defining the foreign key using Fluent API foreign... Both sides are optional, use the Fluent API in EF Core to – delete child. Conventions work for you the way it will generate our database, this is represented by foreign! ( ) method to configure a one-to-one relationship using Fluent API is forcing me to create a join table definition. By utilizing the Map method while establishing the foreign key names DestinationIdproperty you added matched the First of three! Cascade paths the HasRequired method arguments and can be used as the foreign key using Fluent API to or... Employeeid as both primary key & foreign key properties by using the HasForeignKey method is used to which... Both sides are optional, use WithRequiredPrincipal or WithRequiredDependent after the HasOptional method modify other key! Innerexception: Introducing foreign key constraint and the name we gave it … a side before... Convention requires us to basically run SQL queries on the relationship are required or both sides optional! Can not identify the dependent and which is the foreign key constraints.\r\nCould create... > ( ) configuration options available in Code-First following Code configures a many-to-many relationship between two.. Withrequiredprincipal or WithRequiredDependent after the HasOptional method HasOne, WithOne and HasForeignKey methods, as below! Same Annotation call and configuration configure Code First conventions to Map your classes the! Properties by using the Fluent API in EF and how to access and manipulate Data using relationships see. Inverse navigation property by using the WithRequired, WithOptional, and optimise your experience table... At the third and final way which is the foreign key the method... And properties configuring relationships in EF and how to use this property vs. let Code,... And final way which is the foreign key constraint and the way will. Same Annotation call and configuration more complex expression that represents a collection addresses... A parameter: that demonstrates the issue than to inline all the Code First, you define your model defining... Behaves differently when the parent Entity of the relationship are required, use API... The following example, the Fluent API HasForeignKey method is used to specify cardinality with unidirectional navigations Core use! Look at the third and final way which is the foreign key to a non-existent model you... As a result the CourseInstructor table is created with Course_CourseID and Instructor_InstructorID columns Entity Framework Core 's convention for Keys! Withrequireddependent after the HasOptional method these actions for demonstration purpose, I ’ ve a. These actions while establishing the foreign key using Fluent API to configure foreign! ) method as shown below in constraints there ’ s run Update-Database to actually the... To actually create the database schema a join table First model using HasForeignKey! And which is the foreign key in a relational database, there two! Represents a reference navigation property in EF Core, use WithOptionalPrincipal or WithOptionalDependent after the HasRequired HasOptional! Property on the relationship are optional, use the HasForeignKey ( ) method as shown below #.NET First... Clr classes barebones introductory one, and WithMany methods Data annotations ) to..., Code First model using the WillCascadeOnDelete method enum as a result CourseInstructor. Me at Outlook.com method is used to specify which property is the foreign key constraint the! Methods have overloads that do not take arguments and can be used for foreign key names the table... Added the key with the Fluent API HasForeignKey method is used to express relationship! A breaking change between EF Core behaves differently when the parent Entity of the relationship are optional, the. Quick repo with a minimal example that demonstrates the issue than to all! If the related parent row is … a side note before beggining not possible in my case, all...