Implement subclass in inheritance- ing

What is subclass? For example, users have general users and management users. They are all recorded in the User table and identified by a field as a general user or a management user. Let's continue with this example.

You can use a table named users to save the information of common users and administrators. The field identified is a metadata type named userkind. If the value is user, the field is admin and administrator.

Code

/** // <Summary>
/// User
/// </Summary>
Public class users
{
Public int ID;
Public string name;
/** // <Summary>
/// Constructor
/// </Summary>
Public users ()
{
}
}

/** // <Summary>
/// Average user
/// </Summary>
Public class user: Users
{
Public user ()
{
//
// Todo: add the constructor logic here
//
}
}

/** // <Summary>
/// Administrator.
/// </Summary>
Public class admin: Users
{
Public Admin ()
{
//
// Todo: add the constructor logic here
//
}
}

 Ing FileWriting is actually very simple.
Users. HBM. xml

<Hibernate-mapping xmlns = "urn: nhibernate-mapping-2.0">
<Class name = "myentity. Users, myentity" table = "users">
<ID name = "ID" type = "int32">
<Generator class = "native"/>
</ID>
<Discriminator column = "userkind" type = "string"/>
<Property name = "name" type = "string" not-null = "true" length = "50"/>

<Subclass name = "myentity. Admin, myentity" discriminator-value = "user">
</Subclass>
<Subclass name = "myentity. Admin, myentity" discriminator-value = "admin">
</Subclass>
</Class>
</Hibernate-mapping>

 

Note that discriminator and discriminator-value.

Output Data Structure

Configuration CFG = new configuration ();
Cfg. addclass (typeof (users ));
New schemaexport (CFG). Create (True, true );

User and Admin do not need to be added to configuration. Adding a user and Admin will only cause errors.

Persistent Object
Configuration CFG = new configuration ();
Cfg. addclass (typeof (users ));
_ Sessions = cfg. buildsessionfactory ();
User USR = new user ();
USR. Name = "normal user ";
Admin ad = new admin ();
Ad. Name = "Administrator ";
Isession session = This. _ sessions. opensession ();
Session. Save (usr );
Session. Save (AD );

Execution result

Nhibes: insert into users (name, userkind) values (@ P0, 'user'); select scope_identity ()
@ P0 = 'average user'
Nhibes: insert into users (name, userkind) values (@ P0, 'admin'); select scope_identity ()
@ P0 = 'postmaster'

Search

Isession session = This. _ sessions. opensession ();
Int IID = 1;
Int iid2 = 2;
Object OBJ = session. Load (typeof (users), IID );
Object obj2 = session. Load (typeof (users), iid2 );

String str1 = "user ";
String str2 = "user ";
If (obj is admin)
Str1 = "admin ";
If (obj2 is admin)
Str2 = "admin ";
Console. writeline ("obj1 is" + str1 );
Console. writeline ("obj2 is" + str2 );

Result
Obj1 is user
Obj2 is admin.

Directly query general user isession session = This. _ sessions. opensession ();
Int IID = 1;
User USR = (User) Session. Load (typeof (user), IID );
Session. Close ();

Query Process

Nhib.pdf: Select user0 _. ID as id0 _, user0 _. nickname as nickname0 _, user0 _. name as name0 _ from users user0 _ Where user0 _. id = @ P0 and user0 _. userkind = 'user'
@ P0 = '1'