Unable to save modifications of a Lazy<TMemoryStream> field

I load data into an Entity object with a Lazy<TMemoryStream> field. After that I change data in this field and try to save it. No changes appear in the database BLOB field. I use PostgreSQL database server. These are steps to reproduce:

Create database table and fill it with data:

CREATE TABLE public.t_bytea ( id int4 NOT NULL, bdata bytea NULL, CONSTRAINT t_bytea_pk PRIMARY KEY (id) );

INSERT INTO public.t_bytea (id, bdata) VALUES(1, decode('48656C6C6F2C20776F726C6421','hex'));

Create entity class:

[Entity] [Table('t_bytea')] TByteA = class private [Column('id', [cpRequired, cpPrimaryKey, cpNotNull], 0, 0, 0, 'Primary Key')] FId: Integer; [Column('bdata', [], 50, 0, 0, 'BLOB')] FByteA: Lazy<TMemoryStream>; function GetByteA: TMemoryStream; procedure SetByteA(Value: TMemoryStream); public constructor Create; property ID: Integer read FId; property ByteA: TMemoryStream read GetByteA write SetByteA; end;

constructor TByteA.Create; begin FByteA := Lazy<TMemoryStream>.Create( function : TMemoryStream begin Result := TMemoryStream.Create; end, True ); end;

function TByteA.GetByteA: TMemoryStream; begin Result := FByteA; end;

procedure TByteA.SetByteA(Value: TMemoryStream); begin if Assigned(Value) then FByteA.Value.LoadFromStream(Value) else FByteA.Value.Clear; end;

Load data into the entity, modify it and try to save data back to the table:

procedure TForm1.btnAddClick(Sender: TObject); var LStream: TMemoryStream; LStreamWriter: TStreamWriter; LEntity: TByteA; LEntityWrapper: TEntityWrapper; begin LStream := TMemoryStream.Create; LStreamWriter := TStreamWriter.Create(LStream); LEntity := FSession.SingleOrDefault<TByteA>('SELECT * FROM t_bytea WHERE id = 1', []); try LStreamWriter.WriteLine('Hello, world!' + DateTimeToStr(Now)); LEntity.ByteA.LoadFromStream(LStream); // Save modified entity FSession.Save(LEntity); finally LStreamWriter.Close; LStreamWriter.Free; LEntity.Free; end; end;

And there is another one issue. When I load data into an entity object and a BLOB field in a database table is NULL then it's impossible to modify this field in the entity object at all. This is because FByteA.Value does not contain a TMemoryStream object and there is no way to create it properly. If I'm wrong please explain how to do it properly.

Best regards, Leonid.

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