ORM For Delphi

Object Relational Mapping is the idea of being able to write queries using the object-oriented paradigm in your preferred programming language. So this means we are trying to utilize our language to talk with the database instead of using SQL.

Why utilize ORM?

It abstracts away the database system, so switching is easy.
Your queries can be efficient than writing them with SQL.
With ORM, you get lots of features out of the box for instance
- Transactions
- Migrations
- Seeds
- Streams
- Connection Pooling

Delphi community has several Delphi ORM libraries, and the DORM (Delphi ORM) by Daniele Teti is one of the popular and open-source libraries you can use.

DORM has many features available:

Database agnostic (Do not require database changes!)
Has one, has many, and belongs to relations support
Mapping through file, attributes, or CoC
Save and retrieve objects graph, not only single objects
External (file) or internal (resource, json stream) configuration
Interfaces based!
FirebirdSQL (using UIB)
Interbase (using UIB)
SQLServer (using FireDAC driver)
SQLite3 (using this SQLite3 wrapper
and more!

procedure ObjVersionConcurrentTransactionsDEMO;
var
  dormSession, dormSession1, dormSession2: TSession;
  Customer, C1, C2: TCustomerV;
  id: Integer;
begin
  dormSession := TSession.CreateConfigured(
    TStreamReader.Create(CONFIG_FILE), TdormEnvironment.deDevelopment);
  try
    Customer := TCustomerV.Create;
    Customer.Name := 'Daniele Teti Inc.';
    Customer.Address := 'Via Roma, 16';
    Customer.EMail := 'daniele@danieleteti.it';
    Customer.CreatedAt := date;
    dormSession.Persist(Customer);
    id := Customer.id;
    WriteLn('Version: ', Customer.ObjVersion);
    dormSession.Commit(true);
  finally
    dormSession.Free;
  end;

  // read the same object twice
  dormSession1 := TSession.CreateConfigured(
    TStreamReader.Create(CONFIG_FILE), TdormEnvironment.deDevelopment);
  try
    dormSession2 := TSession.CreateConfigured(
      TStreamReader.Create(CONFIG_FILE), TdormEnvironment.deDevelopment);
    try
      // Two users gets the same record
      WriteLn('User1 loads object ' + inttostr(id) + ' and close transaction');
      C1 := dormSession1.Load<TCustomerV>(id);
      dormSession1.Commit;

      WriteLn('User2 loads object ' + inttostr(id) + ' and close transaction');
      C2 := dormSession2.Load<TCustomerV>(id);
      dormSession2.Commit;

      // First user update the object and save it
      C1.Name := 'John Doe';
      C1.ObjStatus := osDirty;
      WriteLn('User1 update object ' + inttostr(id));
      dormSession1.Persist(C1);
      dormSession1.Commit;

      // The second user try to do the same
      C2.Name := 'Jane Doe';
      C2.ObjStatus := osDirty;
      WriteLn('User2 try to update object ' + inttostr(id) + ' (an exception will be raised)');
      dormSession2.Persist(C2); // raise EDORMLockingException
    finally
      dormSession2.Free;
    end;
  finally
    dormSession.Free;
  end;
end;

procedure ObjVersionConcurrentTransactionsDEMO;

var

dormSession, dormSession1, dormSession2: TSession;

Customer, C1, C2: TCustomerV;

id: Integer;

begin

dormSession := TSession.CreateConfigured(

TStreamReader.Create(CONFIG_FILE), TdormEnvironment.deDevelopment);

try

Customer := TCustomerV.Create;

Customer.Name := 'Daniele Teti Inc.';

Customer.Address := 'Via Roma, 16';

Customer.EMail := 'daniele@danieleteti.it';

Customer.CreatedAt := date;

dormSession.Persist(Customer);

id := Customer.id;

WriteLn('Version: ', Customer.ObjVersion);

dormSession.Commit(true);

finally

dormSession.Free;

end;

// read the same object twice

dormSession1 := TSession.CreateConfigured(

TStreamReader.Create(CONFIG_FILE), TdormEnvironment.deDevelopment);

try

dormSession2 := TSession.CreateConfigured(

TStreamReader.Create(CONFIG_FILE), TdormEnvironment.deDevelopment);

try

// Two users gets the same record

WriteLn('User1 loads object ' + inttostr(id) + ' and close transaction');

C1 := dormSession1.Load<TCustomerV>(id);

dormSession1.Commit;

WriteLn('User2 loads object ' + inttostr(id) + ' and close transaction');

C2 := dormSession2.Load<TCustomerV>(id);

dormSession2.Commit;

// First user update the object and save it

C1.Name := 'John Doe';

C1.ObjStatus := osDirty;

WriteLn('User1 update object ' + inttostr(id));

dormSession1.Persist(C1);

dormSession1.Commit;

// The second user try to do the same

C2.Name := 'Jane Doe';

C2.ObjStatus := osDirty;

WriteLn('User2 try to update object ' + inttostr(id) + ' (an exception will be raised)');

dormSession2.Persist(C2); // raise EDORMLockingException

finally

dormSession2.Free;

end;

finally

dormSession.Free;

end;

Here you can download the Delphi ORM!

embarcadero delphi delphi orm object resource mapping 4264149

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2 Comments

Marcelo

September 12, 2022 at 9:43 pm

Hi eveeyone. My name is Marcelo.
I am a Newbye in delphi.
Please, my question tag is.
Dorm is a Delphs native ORM?

TANKS

Reply

Ian Barker

September 15, 2022 at 11:40 am

If I understand your question correctly you are asking “is Dorm an ORM system written in Delphi” – the answer is yes.


Marcelo

September 12, 2022 at 9:43 pm

Hi eveeyone. My name is Marcelo.
I am a Newbye in delphi.
Please, my question tag is.
Dorm is a Delphs native ORM?

TANKS
- Reply
  
  Ian Barker
  
  September 15, 2022 at 11:40 am
  
  If I understand your question correctly you are asking “is Dorm an ORM system written in Delphi” – the answer is yes.

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