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How to remove items from c++ model inside qml?

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  • F flashmozzg

    My model is subclass of QAbstractListModel
    What methods should I implement? I guess it's deleteRows but how do I "call" them inside of qml code? Especially if I don't have access to my model (or it's methods because of some strange qt magic which turns my model to QQmlDMAbstractItemModelData which has all the rolls but no methods, and I don't want to store my model as property in all qml delegates)
    I mean then I do something like role = data it implicitly calls setData, when I just use role it uses data(). But how to make it remove current item (at index)?

    p3c0P Offline
    p3c0P Offline
    p3c0
    Moderators
    wrote on last edited by
    #2

    Hi @flashmozzg
    You can create a Q_INVOKABLE function in C++ model which will internally call removeRow. Current item row can be retrieved from the QML itself and then pass to this function.

    157

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    • F Offline
      F Offline
      flashmozzg
      wrote on last edited by
      #3

      @p3c0 said:

      Hi @flashmozzg
      You can create a Q_INVOKABLE function in C++ model which will internally call removeRow. Current item row can be retrieved from the QML itself and then pass to this function.

      Yeah I ended up doing like that. With propagating remove signal to the top and then deleting it. Was hoping there was some built-in mechanism for doing that like there is for reading and modifying items data.

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      • C Offline
        C Offline
        CoderJeff
        wrote on last edited by
        #4

        I have the same question. But I did not solve it using removeRow.

        In C++ (Q_INVOKABLE):
        void MyCppClass::remove(const int idx)
        {
        bool bExe = mySqlModel->removeRow(idx);
        }

        In QML:
        TableView {
        id: tableView
        ......
        }

        Button{
        onClicked: myCppClass.remove(tableView.currentRow);
        }

        The application output is:
        QSqlQuery::value: unknown field name ''

        Is there anything wrong with my code?

        p3c0P 1 Reply Last reply
        0
        • C CoderJeff

          I have the same question. But I did not solve it using removeRow.

          In C++ (Q_INVOKABLE):
          void MyCppClass::remove(const int idx)
          {
          bool bExe = mySqlModel->removeRow(idx);
          }

          In QML:
          TableView {
          id: tableView
          ......
          }

          Button{
          onClicked: myCppClass.remove(tableView.currentRow);
          }

          The application output is:
          QSqlQuery::value: unknown field name ''

          Is there anything wrong with my code?

          p3c0P Offline
          p3c0P Offline
          p3c0
          Moderators
          wrote on last edited by
          #5

          @CoderJeff IsmySqlModel a subclass of QSqlQueryModel ?

          157

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          • p3c0P p3c0

            @CoderJeff IsmySqlModel a subclass of QSqlQueryModel ?

            C Offline
            C Offline
            CoderJeff
            wrote on last edited by CoderJeff
            #6

            @p3c0
            No, mySqlModel is a subclass of QSqlTableModel.

            p3c0P 1 Reply Last reply
            0
            • C CoderJeff

              @p3c0
              No, mySqlModel is a subclass of QSqlTableModel.

              p3c0P Offline
              p3c0P Offline
              p3c0
              Moderators
              wrote on last edited by
              #7

              @CoderJeff Are you sure tableView.currentRow returns a valid row ?

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              • p3c0P p3c0

                @CoderJeff Are you sure tableView.currentRow returns a valid row ?

                C Offline
                C Offline
                CoderJeff
                wrote on last edited by CoderJeff
                #8

                @p3c0 said:

                @CoderJeff Are you sure tableView.currentRow returns a valid row ?

                Yes, I debug my code, and the input parameter idx is correct.

                There are six rows. I checked each row's index: 0,1,2,3,4,5.

                p3c0P 1 Reply Last reply
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                • C CoderJeff

                  @p3c0 said:

                  @CoderJeff Are you sure tableView.currentRow returns a valid row ?

                  Yes, I debug my code, and the input parameter idx is correct.

                  There are six rows. I checked each row's index: 0,1,2,3,4,5.

                  p3c0P Offline
                  p3c0P Offline
                  p3c0
                  Moderators
                  wrote on last edited by
                  #9

                  @CoderJeff Ok. Not sure then. I guess there's some other code that is causing the problem.

                  157

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                  • p3c0P p3c0

                    @CoderJeff Ok. Not sure then. I guess there's some other code that is causing the problem.

                    C Offline
                    C Offline
                    CoderJeff
                    wrote on last edited by
                    #10

                    @p3c0

                    The entire code is the following.

                    In C++ (Q_INVOKABLE):
                    void MyCppClass::remove(const int idx)
                    {
                    bool bExe = mySqlModel->removeRow(idx);
                    }

                    (Q_INVOKABLE)
                    QObject* MyCppClass::selectModel()
                    {
                    return mySqlModel->selectModel();
                    }

                    MySqlModel* MySqlModel::selectModel()
                    {
                    QString strQuery("SELECT field1,field2,field3 FROM table WHERE field1='a'");
                    setQuery(QSqlQuery(strQuery));
                    return this;
                    }

                    TableView {
                    id: tableView
                    TableViewColumn{ role: "field1"; title: "Field1"}
                    TableViewColumn{ role: "field2"; title: "Field2"}
                    TableViewColumn{ role: "field3"; title: "Field3"}
                    model: myCppClass.selectModel()
                    ......
                    }

                    Button{
                    onClicked: myCppClass.remove(tableView.currentRow);
                    }

                    p3c0P 1 Reply Last reply
                    0
                    • C CoderJeff

                      @p3c0

                      The entire code is the following.

                      In C++ (Q_INVOKABLE):
                      void MyCppClass::remove(const int idx)
                      {
                      bool bExe = mySqlModel->removeRow(idx);
                      }

                      (Q_INVOKABLE)
                      QObject* MyCppClass::selectModel()
                      {
                      return mySqlModel->selectModel();
                      }

                      MySqlModel* MySqlModel::selectModel()
                      {
                      QString strQuery("SELECT field1,field2,field3 FROM table WHERE field1='a'");
                      setQuery(QSqlQuery(strQuery));
                      return this;
                      }

                      TableView {
                      id: tableView
                      TableViewColumn{ role: "field1"; title: "Field1"}
                      TableViewColumn{ role: "field2"; title: "Field2"}
                      TableViewColumn{ role: "field3"; title: "Field3"}
                      model: myCppClass.selectModel()
                      ......
                      }

                      Button{
                      onClicked: myCppClass.remove(tableView.currentRow);
                      }

                      p3c0P Offline
                      p3c0P Offline
                      p3c0
                      Moderators
                      wrote on last edited by
                      #11

                      @CoderJeff Can you check if mySqlModel has data ?
                      You can check it by using record.

                      mySqlModel->record(idx).value(0).toString() // checking value at column 0 and converting it to string
                      

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                      • p3c0P p3c0

                        @CoderJeff Can you check if mySqlModel has data ?
                        You can check it by using record.

                        mySqlModel->record(idx).value(0).toString() // checking value at column 0 and converting it to string
                        
                        C Offline
                        C Offline
                        CoderJeff
                        wrote on last edited by
                        #12

                        @p3c0

                        You are right. It is empty.

                        I will check the logic.

                        1 Reply Last reply
                        0
                        • p3c0P p3c0

                          @CoderJeff Can you check if mySqlModel has data ?
                          You can check it by using record.

                          mySqlModel->record(idx).value(0).toString() // checking value at column 0 and converting it to string
                          
                          C Offline
                          C Offline
                          CoderJeff
                          wrote on last edited by p3c0
                          #13

                          @p3c0

                          A weird phenomenon. If using QSqlTableModel, the result is invalid. But if using QSqlQueryModel, the result is the expected.

                          Why?

                          The following is my debugging code.

                          MySqlModel* MySqlModel::selectModel()
                          {
                          QString strQuery("SELECT field1,field2,field3 FROM table WHERE field1='a'");
                          
                              QVariant val0;
                              QVariant val1;
                          
                              setQuery(QSqlQuery(strQuery));
                              val0 =  record(0).value(0);  //Invalid
                              val1 =  record(0).value(1);  //Invalid
                          
                              QSqlQueryModel model;
                              model.setQuery(strQuery);
                              val0 =  model.record(0).value(0);  //Correct. The result is the expected.
                              val1 =  model.record(0).value(1);  //Correct. The result is the expected.
                          
                          return this;
                          }
                          
                          p3c0P 1 Reply Last reply
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                          • C CoderJeff

                            @p3c0

                            A weird phenomenon. If using QSqlTableModel, the result is invalid. But if using QSqlQueryModel, the result is the expected.

                            Why?

                            The following is my debugging code.

                            MySqlModel* MySqlModel::selectModel()
                            {
                            QString strQuery("SELECT field1,field2,field3 FROM table WHERE field1='a'");
                            
                                QVariant val0;
                                QVariant val1;
                            
                                setQuery(QSqlQuery(strQuery));
                                val0 =  record(0).value(0);  //Invalid
                                val1 =  record(0).value(1);  //Invalid
                            
                                QSqlQueryModel model;
                                model.setQuery(strQuery);
                                val0 =  model.record(0).value(0);  //Correct. The result is the expected.
                                val1 =  model.record(0).value(1);  //Correct. The result is the expected.
                            
                            return this;
                            }
                            
                            p3c0P Offline
                            p3c0P Offline
                            p3c0
                            Moderators
                            wrote on last edited by p3c0
                            #14

                            @CoderJeff According to the doc here, setTable should be used instead of setQuery for QSqlTableModel.

                            157

                            C 1 Reply Last reply
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                            • p3c0P p3c0

                              @CoderJeff According to the doc here, setTable should be used instead of setQuery for QSqlTableModel.

                              C Offline
                              C Offline
                              CoderJeff
                              wrote on last edited by CoderJeff
                              #15

                              @p3c0 said:

                              @CoderJeff According to the doc here, setTable should be used instead of setQuery for QSqlTableModel.

                              The cause is not as simple as I expected. Although I change MySqlModel's parent class to QSqlQueryModel instead of QSqlTableModel, it still does not work. But if using QSqlQueryModel directly, it works.

                              I am confusing.

                              class MySqlModel : public QSqlQueryModel
                              {
                              }

                              MySqlModel* MySqlModel::selectModel()
                              {
                              QString strQuery("SELECT field1,field2,field3 FROM table WHERE field1='a'");

                              QVariant val0;
                              QVariant val1;
                              
                              //using MySqlQueryModel
                              setQuery(strQuery);
                              val0 =  record(0).value(0);  //Invalid
                              val1 =  record(0).value(1);  //Invalid
                              
                              //using QSqlQueryModel directly
                              QSqlQueryModel model;
                              model.setQuery(strQuery);
                              val0 =  model.record(0).value(0);  //Correct. The result is the expected.
                              val1 =  model.record(0).value(1);  //Correct. The result is the expected.
                              

                              return this;
                              }

                              p3c0P 1 Reply Last reply
                              0
                              • C CoderJeff

                                @p3c0 said:

                                @CoderJeff According to the doc here, setTable should be used instead of setQuery for QSqlTableModel.

                                The cause is not as simple as I expected. Although I change MySqlModel's parent class to QSqlQueryModel instead of QSqlTableModel, it still does not work. But if using QSqlQueryModel directly, it works.

                                I am confusing.

                                class MySqlModel : public QSqlQueryModel
                                {
                                }

                                MySqlModel* MySqlModel::selectModel()
                                {
                                QString strQuery("SELECT field1,field2,field3 FROM table WHERE field1='a'");

                                QVariant val0;
                                QVariant val1;
                                
                                //using MySqlQueryModel
                                setQuery(strQuery);
                                val0 =  record(0).value(0);  //Invalid
                                val1 =  record(0).value(1);  //Invalid
                                
                                //using QSqlQueryModel directly
                                QSqlQueryModel model;
                                model.setQuery(strQuery);
                                val0 =  model.record(0).value(0);  //Correct. The result is the expected.
                                val1 =  model.record(0).value(1);  //Correct. The result is the expected.
                                

                                return this;
                                }

                                p3c0P Offline
                                p3c0P Offline
                                p3c0
                                Moderators
                                wrote on last edited by
                                #16

                                @CoderJeff Make sure the query is active before using setQuery.

                                QSqlQuery sq;
                                sq.prepare(strQuery);
                                sq.exec();
                                qDebug() << sq.isActive();
                                setQuery(sq);
                                

                                157

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                                • p3c0P p3c0

                                  @CoderJeff Make sure the query is active before using setQuery.

                                  QSqlQuery sq;
                                  sq.prepare(strQuery);
                                  sq.exec();
                                  qDebug() << sq.isActive();
                                  setQuery(sq);
                                  
                                  C Offline
                                  C Offline
                                  CoderJeff
                                  wrote on last edited by
                                  #17

                                  @p3c0 said:

                                  @CoderJeff Make sure the query is active before using setQuery.

                                  QSqlQuery sq;
                                  sq.prepare(strQuery);
                                  sq.exec();
                                  qDebug() << sq.isActive();
                                  setQuery(sq);
                                  

                                  I tested it in your way, but It still did not work. The query is definitely active because the return value of isActive() is true.

                                  p3c0P 1 Reply Last reply
                                  0
                                  • C CoderJeff

                                    @p3c0 said:

                                    @CoderJeff Make sure the query is active before using setQuery.

                                    QSqlQuery sq;
                                    sq.prepare(strQuery);
                                    sq.exec();
                                    qDebug() << sq.isActive();
                                    setQuery(sq);
                                    

                                    I tested it in your way, but It still did not work. The query is definitely active because the return value of isActive() is true.

                                    p3c0P Offline
                                    p3c0P Offline
                                    p3c0
                                    Moderators
                                    wrote on last edited by p3c0
                                    #18

                                    @CoderJeff Ok. Can you post your complete minimal runnable code somewhere in a zip to test ? Need to check whats actually going on.

                                    157

                                    C 1 Reply Last reply
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                                    • p3c0P p3c0

                                      @CoderJeff Ok. Can you post your complete minimal runnable code somewhere in a zip to test ? Need to check whats actually going on.

                                      C Offline
                                      C Offline
                                      CoderJeff
                                      wrote on last edited by
                                      #19

                                      @p3c0 said:

                                      @CoderJeff Ok. Can you post your complete minimal runnable code somewhere in a zip to test ? Need to check whats actually going on.

                                      I sent you the link. Please check it.

                                      p3c0P 1 Reply Last reply
                                      0
                                      • C CoderJeff

                                        @p3c0 said:

                                        @CoderJeff Ok. Can you post your complete minimal runnable code somewhere in a zip to test ? Need to check whats actually going on.

                                        I sent you the link. Please check it.

                                        p3c0P Offline
                                        p3c0P Offline
                                        p3c0
                                        Moderators
                                        wrote on last edited by p3c0
                                        #20

                                        Hi @CoderJeff,
                                        Your code looks fine. Use method1 or method3 in MySqlModel. The problem is with the view. TableView inside ScrollView seems to break. I just kept TableView in tab01 and everything worked as expected.

                                        157

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                                        • p3c0P p3c0

                                          Hi @CoderJeff,
                                          Your code looks fine. Use method1 or method3 in MySqlModel. The problem is with the view. TableView inside ScrollView seems to break. I just kept TableView in tab01 and everything worked as expected.

                                          C Offline
                                          C Offline
                                          CoderJeff
                                          wrote on last edited by CoderJeff
                                          #21

                                          @p3c0 said:

                                          Hi @CoderJeff,
                                          Your code looks fine. Use method1 or method3 in MySqlModel. The problem is with the view. TableView inside ScrollView seems to break. I just kept TableView in tab01 and everything worked as expected.

                                          What's the meaning of "kept TableView in tab01"? Can you show me the code?

                                          p3c0P 1 Reply Last reply
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