Xdata and Aurelius - How to create an object instance from its class name

BIZ TMS XData
1

Hi,
A way (or an example) for create an object Instance from its class name (in Xdata, refering Aurelius entities)? I need a function that return the correct entity type depending from its class name that is passed as a string parameter.
Thanks a lot!

2

That's just pure Delphi code, you can do it via RTT.
Aurelius itself has a helper class for that, in TMappingExplorer class, which can be accessed, for example, via

Manager.Explorer.ObjectFactory.CreateInstance(MyClass);

But MyClass must be a TClass. To find a class from its name you can use FindClass or TRttiContext.FindType. Here is a reference:

3

Thanks Wagner,

I need help in this scenario:
I need to create a function in Xdata that allows me to deserialize a Json record (from a custom Applyupdate on the client, via json-rpc) in an Aurelius instance, carry out the validation, and then insert the entity into the DB.
However, I would like to generalize and pass the class type as a parameter so that I can insert records into each class of the model, without having to instantiate all the classes at design time, but via RTTi in a single function.

A function prototype:
///
function TSerGenService.ClassDeser(ADeserializer: TXdataJsonClientDeserializer; AClassName: String; AValue: String): TObject;
var
tmpjson: string;
tmpRttiTypeIstance: TRttiInstanceType;
tmpRttiContextChild: TRttiContext;
tmpobj: Tobject;
begin
tmpobj:=nil;
tmpRttiTypeIstance := tmpRttiContextChild.FindType(AClassName) as TRttiInstanceType;
tmpobj := tmpRttiTypeIstance.GetMethod('Create').Invoke(tmpRttiTypeIstance.MetaclassType, ).AsObject;
//// tmpobject must be casted? <<<<<<< ???
tmpobj:= ADeserializer.Read(Avalue); //<<<<<<<<<<< ????
TXDataOperationContext.Current.GetManager.update(tmpobj);
end;
////
Basically I'm looking for a way to generalize data insertion into Xdata via a service, passing the class name and the Json that contains the data.
Could anyone provide me with help on this feature?
Thanks in advance

4

ADeserializer.Read has a non-generic overload where you pass the class type:

tmpobjvalue := ADeserializer.Read(Value, tmpRttiTypeInstance.MetaclassType);
tmpobj := tmpobjvalue.AsObject;
5

Hi Wagner,
You're right, I found it, Thanks.
The problem is that everything works with published properties, while the properties of Aurelius classes are declared public, so they are not created. A way to solve?
Thanks

6

I'm not sure what you are referring to. Can you please elaborate?

8

Hi,
I think that I must enable advanced RTTI for fill Aurelius enities (Aurelius classes have public properties, not Published). Right?
Thanks

9

By default it's not needed, the serializer actually uses private fields for the serialization, and those are already available.