初识kbmmw 中的ORM

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,)] //主键，并自动生成为GUID
        property ID:kbmMWNullable<string> read FID write FID;
        [kbmMW_Field('name:NAME',ftString,)]
        property Name:kbmMWNullable<string> read FName write FName;
        [kbmMW_Field('name:ADDRESS',ftString,)]
        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,)]
        property City:kbmMWNullable<string> read FCity write FCity;
        [kbmMW_Field('name:comments',ftString,)]
        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:='';
   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:='';
   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:='';
   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;