Posts by DirkH

DirkH · mORMot 2

Thanks a lot!

Somehow my brain doesn't like the square braces for this purpose. It seems to be linked to "access array / list element by position / memory offset" (I have to look at much C Code for embedded Systems). I think in this place the GetS() is exactly the same. Are there other places where it's worth to untie my brains knot ?

dict.PathDelim := '.';
Memo2.lines.add('short oneliner: ' + dict.GetS('measurementData.1.note'));

Best regards

DirkH · mORMot 2

I have not yet all my use cases covered but the question how to access "note" from the inner ojbect is solved:
I used IDocList / Dict and it works like a breeze

dict := DocDict('{"text":"Some general Annot. Description","measurementData":[{"id":47,"note":"erster Teil","values":[1.1,1.2,1.3]},{"id":11,"note":"zweiter Teil","values":[2.1,2.2,2.3]}]}');
Memo2.lines.add('oneliner note' + dict.GetL('measurementData').GetD(1).GetS('note'));

DirkH · mORMot 2

Thanks to both of you and especially flydev for this turnkey solution - superb!

Now I'm running into the next Issue I dont understand. Since JSON creation works so great I'm trying to read it back.
ObjLoadJson works fine if JSON and Object structure exactly match. However I need to tolerate if it is (slightly) modified by the user or if there is an update in the structure I need to read an old one or introduce new fields.

I wanted to do that with TDocVaraiant, but I cant Acces fields in the "measurementData" array of objects.

TDocVariantData(item).S['note'] fails in mormot.core.variants TDocVariantData.GetValueIndex because it expects cardinal(VType) = DocVariantVType, which is in my case (16396 = 271, obviously fail -> result-1)

procedure TForm1.Button9Click(Sender: TObject);
Var
  doc: variant;
  item: variant;
Begin
  doc := _Json('{"text":"Some general Description","measurementData":[{"id":47,"note":"erster Teil","values":[1.1,1.2,1.3]},{"id":11,"note":"zweiter Teil","values":[2.1,2.2,2.3]}]}');
  item := TDocVariantData(doc).A['measurementData'].Value[1];

  Memo2.Lines.Clear;
  Memo2.lines.add('Raw second element: ' + VariantToUtf8(TDocVariantData(doc).A['measurementData'].Value[1]));    //returns {"id":11,"note":"zweiter Teil","values":[2.1,2.2,2.3]}
  Memo2.lines.add('note: ' + TDocVariantData(item).S['note']);  //fails "property note not found"
End;

DirkH · mORMot 2

Thank you for you answer,

I'm lost in some rabbit hole Every hour I'm working with it I'm more confused.
I'm using Lazarus 4.2 FPC 3.2.2

At least for now I put everything into records, and used TArray instead of IList. My best guess so far is documented at https://github.com/D-H-R/mormot_json/bl … /unit1.pas.
I know that RecordSaveJson is supposed to do base64 encoding, I wasn't able to get s.th. else running

As you might have expected I need a human readable format.

Can you please point out to me which classes (for data holding) and functions for the "toJson" I should use for a first approach.

Thank you so much.

DirkH · mORMot 2

Hello, everyone

I want to store and retrieve the data of an object with a list property in a json string. However I have a hard time getting this to work. I would appreciate some hints were I can find examples or if it is a good practice using a list instead of an array at all.

Thanks and best regards

My current failing example code:

  TItem = Record
    Name: String;
  End;

  TStorage = Class
  Private
    fPlace: RawUtf8;
    fItems: IList < TItem > ;
  Published
    Property Place: RawUtf8 Read fPlace Write fPlace;
    Property Items: IList < TItem > Read fItems Write fItems;
  End; 
[...]
Procedure TForm1.Button1Click(Sender: TObject);
Var
  Storage: TStorage;
  Item: TItem;
Begin
  Storage := TStorage.Create;
  Storage.Place := 'Ocean';
  Storage.Items := Collections.NewPlainList < TItem > ;

  Item.Name := 'Foo';
  Storage.Items.Add(Item);
  Item.Name := 'Bar';
  Storage.Items.Add(Item);

  Memo1.text := ObjectToJson(Storage, [woHumanReadable]);      //does not print Items
End;

mORMot Open Source

#1 Re: mORMot 2 » lists in objects to Json » 2025-10-02 07:59:35

#2 Re: mORMot 2 » lists in objects to Json » 2025-10-01 14:01:17

#3 Re: mORMot 2 » lists in objects to Json » 2025-10-01 07:13:27

#4 Re: mORMot 2 » lists in objects to Json » 2025-09-27 10:40:58

#5 mORMot 2 » lists in objects to Json » 2025-09-26 11:09:03

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