Entity type in EF (EF basics Series 6), ef entity

Entity type in EF (EF basics Series 6), ef entity

EF has two types of entities: POCO Entity and dynamic proxy entity.

POCO Entity (Plain Old CLR Object)

POCO class is a class that does not depend on any base class of the. NET framework. It is like any other common class. This is why it is called "Plain Old CLR Object;

These POCO entities generated by the object data model support most addition, deletion, query, and modification functions. The following is a Studnet POCO entity:

public class Student        {            public Student()            {                this.Courses = new List<Course>();            }                public int StudentID { get; set; }            public string StudentName { get; set; }            public Nullable<int> StandardId { get; set; }                public Standard Standard { get; set; }            public StudentAddress StudentAddress { get; set; }            public IList<Course> Courses { get; set; }        }        

Dynamic Proxy (POCO Proxy ):

Dynamic proxy is a proxy class in POCO object running state. It is like a POCO object packaging class. Dynamic packaging entities support lazy loading and automatic tracking of changed features;

A poco entity must meet the following conditions before it can become a POCO proxy.

1. must be defined as Public

2. It cannot be sealed.

3. cannot be abstract;

4. The navigation attribute must be defined as public virtual;

5. Each set property must be Icollection <T>;

6. In the context class, the option ProxyCreationEnabled must not be false (the default value is true );

The following POCO Student entity meets the preceding conditions and will become a dynamic proxy entity during running;

public class Student        {            public Student()            {                this.Courses = new HashSet<Course>();            }                public int StudentID { get; set; }            public string StudentName { get; set; }            public Nullable<int> StandardId { get; set; }                public virtual Standard Standard { get; set; }            public virtual StudentAddress StudentAddress { get; set; }            public virtual ICollection<Course> Courses { get; set; }        }        

Note: The dynamic proxy is valid for each object by default. However, you can manually disable the dynamic proxy by setting ProxyCreationEnabled in the context class to false;

Context. Configuration. ProxyCreationEnabled = false;

When running, the Student POCO object will become a proxy class:

The proxy class has two attributes: a scalar attribute and a navigation attribute,

The actual values of a scalar property are included in the object. For example, the Student object has the scalar property StudentID and StudentName, which are consistent with the fields in the database;

The navigation attribute points to another associated object. The Student object has a Standard attribute as the navigation attribute, which ensures that the program can navigate from a Student to the associated standard object.