初识kbmmw 中的ORM-阿里云开发者社区

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初识kbmmw 中的ORM

简介: 在kbmmw 5.02.1 中,加入了ORM 的功能(这里可能和其他语言的定义不完全一样),我们就简单的认为 它就是一个类与数据库的转换吧。今天就先介绍一下如何通过kbmmw 的ORM 功能,实现类与数据库的相互 转换和操作。

    在kbmmw 5.02.1 中,加入了ORM 的功能(这里可能和其他语言的定义不完全一样),我们就简单的认为

它就是一个类与数据库的转换吧。今天就先介绍一下如何通过kbmmw 的ORM 功能,实现类与数据库的相互

转换和操作。

 前提条件:delphi 10.2.1

                   kbmmw 5.02.1

                   unidac 7.0.2

                haosql for sql server 2008  非常不错的一个sql 管理器

启动haosql  for sqlserver2008 管理器,启动数据库。

打开delphi ,建立一个标准的工程,放置如图的几个控件

 

设置uniconnection1 连接sql server 2008 数据库

ok

加入几个必要的单元,并设置好初始化代码。

unit mainp;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs,
  kbmMWORM, Vcl.StdCtrls, Data.DB, DBAccess, Uni, kbmMWCustomConnectionPool,
  kbmMWCustomSQLMetaData, kbmMWMSSQLMetaData, kbmMWUniDAC, UniProvider,
  SQLServerUniProvider, DASQLMonitor, UniSQLMonitor ;

type
  TForm2 = class(TForm)
    kbmMWUNIDACConnectionPool1: TkbmMWUNIDACConnectionPool;
    kbmMWMSSQLMetaData1: TkbmMWMSSQLMetaData;
    UniConnection1: TUniConnection;
    Button1: TButton;
    SQLServerUniProvider1: TSQLServerUniProvider;
    UniSQLMonitor1: TUniSQLMonitor;
    Button2: TButton;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
    ORM:TkbmMWORM;
  end;

var
  Form2: TForm2;

implementation

{$R *.dfm}
procedure TForm2.FormCreate(Sender: TObject);
begin
  ORM:=TkbmMWORM.Create(kbmMWUNIDACConnectionPool1); // 建立ORM 对象
  ORM.QueryMode:=mwoqmMixed;
end;

procedure TForm2.FormDestroy(Sender: TObject);
begin
  ORM.Free; // 释放ORM对象
end;

end.

现在新建一个单元,定义一个联系人类,并加入对应的标注信息

unit uContact;

interface
uses  System.Generics.Collections,kbmMWNullable,kbmMWRTTI,  kbmMWORM,DB;


type

    [kbmMW_Table('name:CONTACT')] // 表名为 contact
     TContact = class
     private
        FID:kbmMWNullable<string>;
        FName:kbmMWNullable<string>;
        FAddress:kbmMWNullable<string>;
        FZipCode:kbmMWNullable<string>;
        FCity:kbmMWNullable<string>;
        FComments:kbmMWNullable<string>;
       public
        [kbmMW_Field('primary:true, generator:shortGuid',ftString,40)] //主键,并自动生成为GUID
        property ID:kbmMWNullable<string> read FID write FID;
        [kbmMW_Field('name:NAME',ftString,50)]
        property Name:kbmMWNullable<string> read FName write FName;
        [kbmMW_Field('name:ADDRESS',ftString,80)]
        property Address:kbmMWNullable<string> read FAddress write FAddress;
        [kbmMW_Field('name:ZIPCODE',ftInteger)]
        property ZipCode:kbmMWNullable<string> read FZipCode write FZipCode;
         [kbmMW_Field('name:city',ftString,50)]
        property City:kbmMWNullable<string> read FCity write FCity;
        [kbmMW_Field('name:comments',ftString,200)]
        property Comments:kbmMWNullable<string> read FComments write FComments;
       end;

implementation



initialization
   TkbmMWRTTI.EnableRTTI([TContact]); //开启RTTI 
   kbmMWRegisterKnownClasses([TContact]);//注册 对象

end.

好了,我们返回主窗体, 加入对应的代码,我们先建立对应的表。

procedure TForm2.Button1Click(Sender: TObject);
begin

 ORM.CreateTable([Tcontact]);

end;

编译运行,点创建库 按钮,显示建表成功。

 

我们看看背后发生了什么?首先我们先在 sql monitor 里面,看看后台做了什么?

通过sql monitor, 我们可以非常清晰的看见,kbmmw 先在次数据库中查询是否有这个表,如果没有这个表,则根据Tcontact 中定义的

字段来生成对应的SQL 语句,执行这个SQL,在数据库中生成对应的表。

数据库中生产的完全没问题。我们下一步生成一些数据,看看是否正常。

生成数据代码

procedure TForm2.Button3Click(Sender: TObject);
var
   t1,t2,t3:TContact ;
begin

   t1:=TContact.Create;
   t1.Name:='红鱼儿';
   t1.Address:='不告诉你';
   t1.ZipCode:='1234567';
   t1.City:='四平';
   t1.Comments:='老牌程序猿';

   ORM.Persist(t1);


   t2:=TContact.Create;
   t2.Name:='努力的干';
   t2.Address:='还是不告诉你';
   t2.ZipCode:='54565552';
   t2.City:='泸州';
   t2.Comments:='变形金刚制造者';

   ORM.Persist(t2);

   t3:=TContact.Create;
   t3.Name:='清幽傲竹';
   t3.Address:='就是不告诉你';
   t3.ZipCode:='252556';
   t3.City:='福州';
   t3.Comments:='真的很帅的!';

   ORM.Persist(t3);

  showmessage('操作成功');


end;

看看后台都有那些sql.实际上这个Persist 是更新和插入,如果更新失败就插入。

看看数据库里面的生成数据的效果。

完全正确。

下面看一下如何通过ORM 查询数据。

kbmmw orm 查询数据有三种方式。

 // Query mode controls what syntax to use for queries.
   // mwoqmMW (default) use kbmMW's SQL syntax and automatically
   //   rewrite the query to match supported databases.
   // mwoqmNative provides the query string without alterations to the
   //   database.
   // mwoqmMixed default use kbmMW's SQL syntax with automatic rewrite
   //   unless the first character in the query statement is #
   TkbmMWORMQueryMode = (mwoqmMW,mwoqmNative,mwoqmMixed);

缺省使用kbmmw 自身的SQL 语法,并自动转换成对应的数据库语法

第二种是直接使用目标数据库的语法

第三种是混合方式, 如果查询首字母不是# 的话,就用kbmmw 自身的sql 语法。

我们使用混合模式查询

procedure TForm2.Button5Click(Sender: TObject);
var
   o:TObjectList<Tcontact>;
begin
     o:=TObjectList<Tcontact>(orm.Query(Tcontact,'#SELECT * FROM contact',true));

     showmessage('共有'+o.Count.ToString +'条记录');

     o.Free;

end;

或者

procedure TForm2.Button5Click(Sender: TObject);
var
   o:TObjectList<Tcontact>;
begin
     o:=orm.QueryList<Tcontact>('#SELECT * FROM contact');
     showmessage('共有'+o.Count.ToString +'条记录');
     o.Free;
end;

 

运行结果

后台SQL 亦是如此

 

 我们来查询单条数据,单挑数据有两种查询方式

一种是SQL 方式,一种ORM 方式

先介绍一下sql 方式

procedure TForm2.Button6Click(Sender: TObject);
var
   o:Tcontact;
begin
     o:=orm.Query<Tcontact>('#SELECT * FROM contact WHERE NAME=''红鱼儿''');

     if o=nil then
        begin
          showmessage('没有查询到数据!');
          exit;
        end;

     showmessage(o.Comments);

     o.Free;

end;

运行效果

使用kbmw ORM 方式查询

procedure TForm2.Button7Click(Sender: TObject);
var
   o:Tcontact;
   b:boolean;
begin
     o:=orm.Query<Tcontact>(['name'],['红鱼儿'],mwoqoEQ);
     if o=nil then
         begin
          showmessage('没有查询到数据!');
          exit;
        end;
      showmessage(o.Comments);
     o.Free;

end;

运行结果

修改数据库

procedure TForm2.Button8Click(Sender: TObject);
var
   o:Tcontact;

begin
     o:=orm.Query<Tcontact>(['name'],['红鱼儿'],mwoqoEQ);
     if o=nil then
         begin
          showmessage('没有查询到数据!');
          exit;
        end;

    o.Name:='红鱼儿二代';
    orm.Update(o);

      showmessage('修改成功!');
     o.Free;

end;

结果也一切正常

看看后台发生了什么?

数据库是否保存正确?

没问题,太爽了。

顺便添加一下删除的代码

procedure TForm2.Button9Click(Sender: TObject);
var
   o:Tcontact;

begin
     o:=orm.Query<Tcontact>(['name'],['红鱼儿'],mwoqoEQ);
     if o=nil then
         begin
          showmessage('没有查询到数据!');
          exit;
        end;


    orm.Delete(o);

      showmessage('删除成功!');
     o.Free;

end;

清除全部的数据

procedure TForm2.Button4Click(Sender: TObject);
begin
      orm.PurgeTable(Tcontact);

end;

删除建的表

procedure TForm2.Button2Click(Sender: TObject);
begin
   ORM.DeleteTable([Tcontact])
end;

终于写完了。

大家对上面kbmmw 标注肯定很头疼,第一要记很多标注名,第二不能笔误,这个确实麻烦,

好消息是,作者已经把自动生产这些标注列入计划,期待后面的版本能直接自动生产,那就方便多了。

在没有自动声场之前,请大家参照一下说明,自己手工处理。

// ORM attribute syntax
// ====================
//
// kbmMW_Table - Define a table.
//   Must be used on classes.
//
//   Define a table named person.
//   [kbmMW_Table('name:person')]
//
//   Define 2 ascending indexes i_fieldname, and i_anotherfieldname on the field fieldname and anotherfieldname.
//   [kbmMW_Table('name:person, index:fieldname, index:anotherfieldname...
//
//   Define an ascending index named i1, on the field name
//   [kbmMW_Table('name:person, index:{name:i1,field:name},...
//
//   Define a descending index named i1, on the field name
//   [kbmMW_Table('name:person, index:{name:i1,field:name,descending:true},...
//
//   Define a compound unique index named i2, on the fields name and age. Name field part is descending.
//   [kbmMW_Table('name:person, index:{name:i2,unique:true,fields:[{name:name,descending:true},{name:age}]
//
//
// kbmMW_Field - Define fields in a table.
//   Must be used on properties within a class if they are to be persisted.
//
//   Define a field that will be persisted. Its type will be decided for
//     from the property type. String type fields will have a size of 50.
//     Table field name will be the same as the property name.
//   [kbmMW_Field]
//
//   Define a field that will be persisted. It will accept unicode data of max 50 characters.
//     It will have the same name as the property.
//   [kbmMW_Field(ftWideString,50)]
//
//   Define a field named id, and make it primary key. It will be automatically populated bu the generator shortGuid.
//   [kbmMW_Field('name:id, primary:true, generator:shortGuid',ftString,40)]
//   property ID:kbmMWNullable<string> read FID write FID;
//
//   These generators exists:
//     GUID           - Returns a GUID formatted as a regular GUID {123e4567-e89b-12d3-a456-426655440000}
//     SHORTGUID      - Returns a short GUID where braces and dashes are missing: 123e4567e89b12d3a456426655440000
//     SEQUENCE       - Returns next unique number from a sequence. Provide name of sequencer in sequence property
//                      and optional sequencestart property (not supported by all databases!)
//     DATETIME       - Returns a date time value, formatted according to the dateFormat property.
//
//   Define a field named id, and make it primary key. It will be populated by a sequence generator.
//     Since no sequencer was given, one is automatically generated named s_tablename_fieldname
//   [kbmMW_Field('name:id, primary:true, generator:sequence',ftInteger)]
//   property ID:kbmMWNullable<integer> read FID write FID;
//
//   Define a field named id, and make it primary key. It will be populated by sequence generator SEQ, starting from value 10.
//     (not all databases supports sequencers with a defined start!)
//   [kbmMW_Field('name:id, primary:true, generator:sequence, seqneuce:SEQ1, sequenceStart:10',ftInteger)]
//   property ID:kbmMWNullable<integer> read FID write FID;
//
//   Define a field named id, and make it primary key. It will be populated automatically by the database.
//     (not all databases support auto increment type fields!)
//   [kbmMW_Field('name:id, primary:true',ftAutoInc)]
//   property ID:kbmMWNullable<integer> read FID write FID;
//
//   Define a field named datetime containing date/time values as Delphi local time values.
//   [kbmMW_Field('name:datetime',ftDateTime)]
//   property DateTime:TkbmMWDateTime read FDateTime write FDateTime;
//
//   Define a field named datetime containing date/time values as Delphi UTC values.
//   [kbmMW_Field('name:datetime, dateFormat:UTC',ftDateTime)]
//   property DateTime:TkbmMWDateTime read FDateTime write FDateTime;
//
//   Define a field named datetime containing date/time values as Unix local time millisecs since EPOC.
//   [kbmMW_Field('name:datetime, dateFormat:LOCALSINCEEPOCHMS',ftInt64)]
//   property DateTime:TkbmMWDateTime read FDateTime write FDateTime;
//
//   Define a field named datetime containing date/time values as Unix UTC time millisecs since EPOC.
//   [kbmMW_Field('name:datetime, dateFormat:UTCSINCEEPOCHMS',ftInt64)]
//   property DateTime:TkbmMWDateTime read FDateTime write FDateTime;
//
//   Define a field named datetime containing date/time values as Unix local time secs since EPOC.
//   [kbmMW_Field('name:datetime, dateFormat:LOCALSINCEEPOCH',ftInt64)]
//   property DateTime:TkbmMWDateTime read FDateTime write FDateTime;
//
//   Define a field named datetime containing date/time values as Unix UTC time secs since EPOC.
//   [kbmMW_Field('name:datetime, dateFormat:UTCSINCEEPOCH',ftInt64)]
//   property DateTime:TkbmMWDateTime read FDateTime write FDateTime;
//
//   Define a field named datetime containing date/time values as ISO8601 formatted string.
//   [kbmMW_Field('name:datetime, dateFormat:ISO8601',ftString,50)]
//   property DateTime:TkbmMWDateTime read FDateTime write FDateTime;
//
//   Define a field named datetime containing date/time values as RFC1123 formatted string.
//   [kbmMW_Field('name:datetime, dateFormat:RFC1123',ftString,50)]
//   property DateTime:TkbmMWDateTime read FDateTime write FDateTime;
//
//   Define a field named datetime containing date/time values as NCSA formatted string.
//   [kbmMW_Field('name:datetime, dateFormat:NCSA',ftString,50)]
//   property DateTime:TkbmMWDateTime read FDateTime write FDateTime;
//
// kbmMW_Null - Specify NULL conversion.
//   (This attribute is also used for object marshalling).
//
//   If, for example, a property is of type integer, the property is not directly able to indicate a NULL state since
//   all values of an integer are considered non NULL values.
//   However its possible to define a specific value to be interpreted as NULL.
//   Eg.
//   [kbmMW_Field('name:somefield',ftInteger)]
//   [kbmMW_Null(-1)]
//   property MyProperty:integer read FMyProperty write FMyProperty;
//
//   This will define that the value -1 must be interpreted as NULL when storing and retrieving data
//   from the database.
//
// kbmMW_NotNull - Indicate that the property must never contain the NULL value (either interpreted via the kbmMW_Null attribute or actual).
//   Eg.
//   [kbmMW_Field('name:somefield',ftInteger)]
//   [kbmMW_NotNull]
//   property MyProperty:kbmMWNullable<integer> read FMyProperty write FMyProperty;

 

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