mORMot Open Source

Hi Ab,

We have a weird one. We're trying to use the DI feature where we inject an instance of a configuration reader to our service using ServiceContainer.RegisterGlobal and we ran across a very strange issue.

Sample code here (with all Synopse code removed to show a pure Delphi example):
https://stackoverflow.com/questions/457 … rom-memory

Anyone had to deal with something like this before?

Hi Ab,

We've gone live with our first Rest server and lo and behold the TI team bounced the database server without restarting the REST server. This caused some very strange connections issues as the connections previously instantiated returned errorsm, but new ones worked - it took us a while to figure out what happened!

Researching possible solutions I found http://synopse.info/fossil/info/f024266c0839

I understand the ConnectionTimeOutMinutes property, which is something we'll investigate.

I am wondering about the proposed usage of ExceptionIsAboutConnection, though. How do you for see it being used?

Kind regards,

Willo

Hi Ab,

Playing with Delphi 10 Seattle, I wanted to bring in mORMot, but quickly realised that there's a big issue. System.Contnrs is not supported in mobile projects! That means no TObjectList. 
See mobile white paper:

"Use the generic container classes defined in the unit Generics.Collections. The old-style Contnrs unit is not available on the mobile platform, because it is based on a pointer list (the non-generic TList class) and won’t work properly with the ARC memory management model."

Does that mean no mORMot for mobile projects, or is there a clever work around?

In our quest for ever more robust software, I'm wondering how mORMot deals with a server restart. My tests didn't have a very elegant result. The only solution I found was to recreate the client connection, which is a problem when the connection reference has been passed down through several layers. To my mind it would be ideal if TSQLHttpClient, or some parent, could try and re-establish it's session on receiving a 403.

When fiddling around with transaction handling in Firebird 1.5, using ZEOS, we ran in to an issue where the transaction was not committed and we had to force a commit.

Digging around I found:
fDbConnection.MainConnection.StartTransaction;

Which worked pretty well in the unit tests, but testing it in a service produced an exception:
TSQLDBConnection on xxx should be connected

Forcing the connection before calling StartTransaction resolves the issue, but I'm wondering why TSQLDBConnection behaves this way.

Hi guys,

It seems that all the tools are there, but has anyone tried doing something like this yet?

Hi Ab,

I need to authenticate against an existing user database which calculates a proprietary hash. The easiest way I found to do that was to declare my own TSQLAuthUser. If we make TSQLAuthUser.SetPasswordPlain virtual, I can override the hash calculation and everything works.

Will you apply this to the code base?
    procedure SetPasswordPlain(const Value: RawUTF8); virtual;

I think this part of the library needs some work though, it's very tightly bound. Perhaps if one can abstract it out to use interfaces instead, that would make extending it really easy.

PS Article forthcoming.

Hi guys,

I've been wondering how to implement the multi-legged Accounting Transaction using the ORM as described by Fowler here: http://martinfowler.com/eaaDev/Accounti … ction.html

The ORM might not be the best tool to model this, but it would make for an interesting use case nonetheless.

What I have so far:

  TFinancialEvent = class;

  TTransaction = class( TSQLRecord )
  private
    fAmount: TCurrency;
    fAccount: TLegacyAccount;
    fTransactionDate: TDateTime;
    fStockEvent: TStockEvent;
  published
    property FinancialEvent : TFinancialEvent read fFinancialEvent write fFinancialEvent;
    property TransactionDate : TDateTime read fTransactionDate write fTransactionDate;
    property Account : TLegacyAccount read fAccount write fAccount;
    property Amount : TCurrency read fAmount write fAmount;
  end;

  TFinancialEvent = class( TSQLRecord )
  private
    fEventDate: TDateTime;
  published
    property EventDate : TDateTime read fEventDate;
  end;

Now, a lot of guys would now derive a new class from TFinancialEvent to handle specific events. Let's look at a Stock Procurement event, for instance:

  TStockProcurementEvent = class(TFinancialEvent)
  public
    constructor Create( aStockItem : TLegacyStockItem; aQuantity: Double; aAmount : TCurrency;
      aSupplier : TLegacySupplier; aReceivingLocation : TLegacyAccount; aDate : TDateTime ); reintroduce;
  end;

...

implementation

{ TStockProcurementEvent }

constructor TStockProcurementEvent.Create( aStockItem : TLegacyStockItem; aQuantity: Double; aAmount : TCurrency;
      aSupplier : TLegacySupplier; aReceivingLocation : TLegacyAccount; aDate : TDateTime );
var
  aTransaction : TTransaction;
begin
  inherited Create;
  fEventDate := aDate;

  //First add the Supplier leg
  aTransaction := Self.Add;
  aTransaction.Account := aSupplier;
  aTransaction.Amount := -aAmount;
  aTransaction.TransactionDate := aDate;

  //Then add the Receiver leg
  aTransaction := Self.Add;
  aTransaction.Account := aReceivingLocation;
  aTransaction.Amount := Amount;
  aTransaction.TransactionDate := aDate;
end;

There are some assumptions and the code is far from complete. The one solution I played with was to make TFinancialEvent a descendant from TCollection of TTransaction, which provides a clean separation from the Framework, but then there is no ORM involved.

So then I started playing with keeping a dynamic array of transactions in the Event object, but I haven't found an easy way to of adding or loading slave records using the ORM.

Any suggestions?

Is there an easy way to have mORMot encode Enums as String? I see it's part of the standard serializer, but I can't seem to find a place to customize the serializer's options.