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  4. [SOLVED] Empty QJsonDocument from file
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[SOLVED] Empty QJsonDocument from file

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  • N Offline
    N Offline
    ningu
    wrote on last edited by
    #7

    Yes, the file is properly put in my qrc file.

    And yes, sorry, when I said

    bq. Unfortunately, even though you are right, removing the superfluous comma did not solve the problem. The QDomDocument is still empty.

    I meant the QJsonDocument is still empty.

    But later on I tried to load the data into a QDomDocument object just to try and it seems to work fine.
    @
    QDomDocument *domDocument;
    if (!domDocument->setContent(&file)) {
    qDebug() << "Could not set DOM";
    return;
    }

    qDebug() << domDocument->toString();@

    prints the file contents to the console.

    Sorry for the confusion I created with the typo.

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    • SGaistS Offline
      SGaistS Offline
      SGaist
      Lifetime Qt Champion
      wrote on last edited by
      #8

      Ok, then what does

      @qDebug() << file.readAll()@

      return ?

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      Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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      • N Offline
        N Offline
        ningu
        wrote on last edited by
        #9

        It returns
        @""@

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        • SGaistS Offline
          SGaistS Offline
          SGaist
          Lifetime Qt Champion
          wrote on last edited by
          #10

          Then it seems that your file is empty

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          Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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          • N Offline
            N Offline
            ningu
            wrote on last edited by
            #11

            That's what I thought, but
            @qDebug() << QString::fromUtf8(file.readAll())@
            returns the file contents.

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            • N Offline
              N Offline
              ningu
              wrote on last edited by
              #12

              Might it be an encoding issue?

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              • N Offline
                N Offline
                ningu
                wrote on last edited by
                #13

                Sorry, that was not completely right:
                @QString jsonString = QString::fromUtf8(file.readAll());
                qDebug() << jsonString;
                @
                returns the file contents, while
                @qDebug() << QString::fromUtf8(file.readAll())@
                returns
                @""@

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                • SGaistS Offline
                  SGaistS Offline
                  SGaist
                  Lifetime Qt Champion
                  wrote on last edited by
                  #14

                  Strange, QJsonDocument should handle it...
                  Did you check what error you got when using fromJson ?

                  Interested in AI ? www.idiap.ch
                  Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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                  • N Offline
                    N Offline
                    ningu
                    wrote on last edited by
                    #15

                    No, I didn't. How could I do that?

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                    • N Offline
                      N Offline
                      ningu
                      wrote on last edited by
                      #16

                      Ok, I got it. A friend of mine pointed me out that I was looking for the array in the QJsonDocument, and that I should probably be looking for the object, which worked.

                      The only thing that doesn't work right is that
                      @QString jsonString = QString::fromUtf8(file.readAll());

                      QJsonDocument jsonDoc = QJsonDocument::fromJson(jsonString.toUtf8());@
                      works, but
                      @QJsonDocument jsonDoc = QJsonDocument::fromJson(file.readAll());@
                      doesn't.

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                      • SGaistS Offline
                        SGaistS Offline
                        SGaist
                        Lifetime Qt Champion
                        wrote on last edited by
                        #17

                        Look at the second parameter of "fromJson":http://qt-project.org/doc/qt-5.0/qtcore/qjsondocument.html#fromJson

                        From there you can get the error

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                        Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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                        • N Offline
                          N Offline
                          ningu
                          wrote on last edited by
                          #18

                          It's an 'Illegal value' error. But I get the same error even with an empty file.

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                          • SGaistS Offline
                            SGaistS Offline
                            SGaist
                            Lifetime Qt Champion
                            wrote on last edited by
                            #19

                            Could it be your json file encoding that is problematic ?

                            Interested in AI ? www.idiap.ch
                            Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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                            • N Offline
                              N Offline
                              ningu
                              wrote on last edited by
                              #20

                              That might be it. Is there a way to make sure the file is UTF8? Or set it to UTF8?

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                              • SGaistS Offline
                                SGaistS Offline
                                SGaist
                                Lifetime Qt Champion
                                wrote on last edited by
                                #21

                                If you are using QtCreator you could check the editor settings to ensure that it uses UTF8

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                                Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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                                • N Offline
                                  N Offline
                                  ningu
                                  wrote on last edited by
                                  #22

                                  Ah, that did it!

                                  Thank you very much for all your help SGaist!

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                                  • SGaistS Offline
                                    SGaistS Offline
                                    SGaist
                                    Lifetime Qt Champion
                                    wrote on last edited by
                                    #23

                                    You're welcome !

                                    If everything is working now, please update the thread's title to solved so other forum users may know a solution has been found :)

                                    Interested in AI ? www.idiap.ch
                                    Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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                                    • V Offline
                                      V Offline
                                      VTiTux
                                      wrote on last edited by
                                      #24

                                      Hi,

                                      I have the same problem, but the solution isn't the UTF8 coding, for me.
                                      QtCreator is already configured to UTF, and that
                                      @ QString jsonString = QString::fromUtf8(file.readAll());

                                      QJsonDocument jsonDoc = QJsonDocument::fromJson(jsonString.toUtf8());
                                      

                                      @
                                      don't work for me.

                                      My JSON file is built and written by JsonDocument and QFile, so, it could be valide:
                                      @
                                      bool JSONStorage::storeJSONFile(){
                                      if( !jsonFile.open(QIODevice::WriteOnly | QIODevice::Text | QIODevice::Truncate) ){
                                      return false;
                                      }
                                      QJsonDocument jsonDocument( jsonArray );
                                      jsonFile.write( jsonDocument.toJson() );
                                      jsonFile.close();
                                      return true;
                                      }
                                      @

                                      But I do not manage to load this file. I use this method:
                                      @
                                      void JSONStorage::openJSONFile(){
                                      QJsonParseError parseErr;
                                      QJsonDocument jsonDocument;

                                      if( !jsonFile.open(QIODevice::ReadOnly | QIODevice::Text) ){
                                          return;
                                      }
                                      
                                      jsonDocument.fromJson( jsonFile.readAll(), &parseErr );
                                      qDebug() << parseErr.errorString();
                                      if( jsonDocument.isEmpty()){
                                          qDebug() << "Empty!";
                                      }
                                      if( jsonDocument.isArray() ){
                                          qDebug() << "Is array";
                                          jsonArray = jsonDocument.array();
                                      }
                                      

                                      }
                                      @

                                      It says that is empty, and parseErr: "no error occurred"

                                      If I write:
                                      @
                                      qDebug() << jsonFile.readAll();
                                      @

                                      I can see my document. It isn't empty!

                                      What is wrong?

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                                      • V Offline
                                        V Offline
                                        VTiTux
                                        wrote on last edited by
                                        #25

                                        Is it because my main object is an array?

                                        I go to eating and I will retry with an JsonObject to the root, later.

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                                        • SGaistS Offline
                                          SGaistS Offline
                                          SGaist
                                          Lifetime Qt Champion
                                          wrote on last edited by
                                          #26

                                          Use the second parameter of fromJson(const QByteArray & json, QJsonParseError * error = 0) and check what it returns

                                          Interested in AI ? www.idiap.ch
                                          Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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