mORMot Open Source

avista

Member

Registered: 2014-01-06

Posts: 63

JSON Default Serialization Options

When defining JSON serialization options, I currently need to set the options for each record.

For example:

var
  Options: TJSONCustomParserSerializationOptions;
begin
  Options := [soReadIgnoreUnknownFields];
  TTextWriter.RegisterCustomJSONSerializerSetOptions(TypeInfo(TRecord_1), Options, True);
  TTextWriter.RegisterCustomJSONSerializerSetOptions(TypeInfo(TRecord_2), Options, True);
  TTextWriter.RegisterCustomJSONSerializerSetOptions(TypeInfo(TRecord_3), Options, True);
end;

However, if I forget to register a new record, then I invariably run into parsing problems when the users of my REST service include unknown fields.

So, I created a singleton method to be able to specify default options:

var
  Options: TJSONCustomParserSerializationOptions;
begin
  Options := [soReadIgnoreUnknownFields];
  TJSONRecordAbstract.SetDefaultSerializationOptions(Options);
end;

Would it be possible to include this in the official code?  Here are my proposed changes:

var
  DefaultTextWriterJSONClass: TTextWriterClass = TTextWriter;
  DefaultTextWriterTrimEnum: boolean;
  DefaultSerializationOptions: TJSONCustomParserSerializationOptions; //<----------

class procedure TJSONRecordAbstract.SetDefaultSerializationOptions(aOptions: TJSONCustomParserSerializationOptions);
begin
  DefaultSerializationOptions := aOptions;
end;

function TJSONRecordAbstract.CustomReader(P: PUTF8Char; var aValue; out aValid: Boolean): PUTF8Char;
var Data: PByte;
begin
  Data := @aValue;
  fOptions := fOptions + DefaultSerializationOptions; //<-----------------
  aValid := Root.ReadOneLevel(P,Data,Options);
  result := P;
end;

procedure TJSONRecordAbstract.CustomWriter(const aWriter: TTextWriter; const aValue);
var P: PByte;
begin
  P := @aValue;
  fOptions := fOptions + DefaultSerializationOptions; //<-----------------
  Root.WriteOneLevel(aWriter,P,Options);
end;

Perhaps there is a better/cleaner way to achieve this, but this was the only way I could find to get it to work.

Thanks

ab

Administrator

From: France

Registered: 2010-06-21

Posts: 14,242

Website

Re: JSON Default Serialization Options

This would break how options are expected to work.

Sometimes, you just disable some options on purpose.
With your patch, it would enable those options...

avista

Member

Registered: 2014-01-06

Posts: 63

Re: JSON Default Serialization Options

Fair enough. 

If there's no straightforward way to achieve this then I guess I'll just continue registering every DTO in my project and will deal with the inevitable "PerThread execution failed (probably due to bad input parameters)" error on a case by case basis.