![]() For this tutorial we will consider a table that stores Songs details such as name, genre, artist, rating, download link etc. The Spring Data & JPA does support composite primary keys and today we will see how. Composite id with use EbeddedId, create a class with the properties that will be used as the composite key as shown below. As an alternative, we can create a Primary Key of multiple columns which is called as Composite Primary Key. You can also map and configure the properties of your domain classes using Fluent API.1. The Property method is used to obtain a configuration object for a given property. As they are, the Blog and Post classes conveniently follow code first convention and require no tweaks to enable EF compatability. The Property method is used to configure attributes for each property belonging to an entity or complex type. I’ll demonstrate Code First DataAnnotations with a simple pair of classes: Blog and Post. For more information, see Mapping arbitrary data. When the database is generated you see the following tables in your database as shown in the following image. If the primary key is composite (partition key and sort key), you can use this tag to map your class field to the sort key. StudentEnrollmentInfo − Contains EnrollmentDate. StudentData − Contains Student FirstMidName and Last Name. In the above code, you can see that Student entity is split into the following two tables by mapping some properties to StudentData table and some properties to StudentEnrollmentInfo table using Map method. ModelBuilder.Entity().ToTable("EnrollmentInfo") ModelBuilder.Entity().ToTable("CourseDetail") In this chapter, we will continue with the simple example which contains Student, Course and Enrollment classes and one context class with M圜ontext name as shown in the following code. A key associated with ORM-mapped objects that identifies their primary key identity within the database, as well as their unique identity within a Session. ![]() Fluent API supports the following types of mappings. Composite keys can only be configured using the Fluent API - conventions will never setup a composite key and you can not use Data Annotations to configure one. In EF 6, the Key attribute along with the Column attribute can be applied to multiple properties of an entity class which will create composite primary key columns in the database. I have a special case with legacy data where a FK property is required but may or may not reference a record in the relationship. The Code First Fluent API is most commonly accessed by overriding the OnModelCreating method on your derived DbContext.įluent API provides more functionality for configuration than DataAnnotations. Setting Foreign Key attributes (annotations) with the Required attribute will also enforce EF required navigation properties EVEN WHEN the FK property is nullable. Data annotations and the fluent API can be used together, but Code First gives precedence to Fluent API > data annotations > default conventions.įluent API is another way to configure your domain classes. In Entity Framework, we can use it to create Composite Primary key, while in EF Core it is not supported. Please read our previous article where we discussed Column Data Annotation Attribute in Entity Framework Code First Approach with Examples. ![]() In this article, I am going to discuss Key Data Annotation Attributes in Entity Framework Code First Approach with Examples. Through the use of Data Annotations or the Entity Framework Fluent API you may control the table name, as well as the table owner. This attribute is applicable to both Entity Framework & Entity Framework Core. Key Attribute in Entity Framework with Examples. 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. Data Annotations Key Attribute in EF Core The Key Attribute or Primary key attribute maps the property as the primary key column in the database.
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