EagerLoad association on inheritance

[MVF_MVF]

Hi,
 How to EagerLoad TPerson5.PhotoId?
 Manager.Find<TPerson1>.CreateAlias(TPerson5.PhotoId.AssociationName,
TPerson5.PhotoId.AssociationName, TFetchMode.Eager).List; // someting like this

 TPerson1 = class
 private
    FId: Int64;
    FName: string;
 end;

 TPerson2 = class (TPerson1)
 private
    FId: Int64;
 end;

 TPerson3 = class (TPerson2)
 private
    FId: Int64;
 end;

 TPerson4 = class (TPerson3)
 private
    FId: Int64;
 end;

 TPerson5 = class (TPerson4)
 private
    FId: Int64;
    FPhotoId: TPhoto;
 end;

 TPhoto = class
 private
    FId: Int64;
    FPhotoPath: String;
 end;

Thanks

[wlandgraf (Wagner Landgraf)]

Unfortunately there is no polymorphism in CreateAlias and eager loading, unfortunately. You can only do that if you do a Find<TPhoto5>, not Find<TPhoto1>

[MVF_MVF]

Hi
 

Unfortunately it does not work, because i need all type of Persons (TPerson1,TPerson2, etc..).
It's a big issue for me. Any Sugestion?

thanks

[wlandgraf (Wagner Landgraf)]

Unfortunately not, for now. The only workaround would be mapping the property as eager loading.

[MVF_MVF]

Hi, Wagner
  Makes sense set property as eager loading in runtime before execute, and remove property after execute? (Using Datasnap + rest + json)

  Something like:
  if eagerLoad then
     AddEagerLoad;
   Result := Manager.Find<TPerson1>.List;
   RemoveEagerLoad;

Thanks  
    

    


  thanks

[wlandgraf (Wagner Landgraf)]

You could try to do that manually manipulating the mapping in TMappingExplorer. But note that TMappingExplorer is not thread-safe, if you do that in DataSnap, you would have to create a specific TMappingExplorer for that.

EagerExplorer := TMappingExplorer.Create;

EagerExplorer.GetColumnByPropertyName(TPerson5, 'FPhotoId').IsLazy := False;

[MVF_MVF]

Hi, Wagner
  Does not work, i believe it's because MaxEagerFetchDepth=3.
thanks
 

[wlandgraf (Wagner Landgraf)]

If MaxEagerFetchMode is 3, then it should load, because FPhoto is just the first level (your are retrieving TPerson directly).

[MVF_MVF]

Hi, Wagner
   instead of
   "EagerExplorer.GetColumnByPropertyName(TPerson5, 'FPhotoId').IsLazy := False;"
    use
    "EagerExplorer.GetAssociationByPropertyName(TPerson5,  'FPhotoId').Lazy := False;"
Works fine,
thanks