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Dynamically change delegate QTableView

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  • E Offline
    E Offline
    EagleWatch
    wrote on last edited by
    #1

    I have a QTableView displaying data (filtered) of a QSqlRelationalTableModel.
    I also have a delegate for the second column in my QTableView.

    This delegate provides me to chose an item in a combox.

    My QTableView is displaying filtered data based on another combobox.
    What I would like to get is also change the delegate.

    I can change the relation, howerver, when I'm enterring in the cell to changing value in the combobox, the combobox resets itself to the first relation.

    Here is an example :
    CBO is the combobox outside the QTableView
    CBDEL is the combobox in the QTableView (delegate)

    CBO is getting these values : "Disponibility", "Integrity"
    When the application starts, default value fot CBO is "Disponibility", and CBDEL has these values : "24h" and "72h".

    When I change the CBO to the value "Integrity", the CBDEL should get these values : "Yes" and "No". But it's not.

    I don't know how to manage multiple QAbstractItemDelegate for the same column.

    Here my code :

    evenementsRedoutesModele->setTable("evenementsRedoutes");;
    evenementsRedoutesModele->setEditStrategy(QSqlTableModel::OnManualSubmit);
    evenementsRedoutesModele->setRelation(3, QSqlRelation("critereDisponibilite", "id", "niveau"));
    ui->comboBoxCriteresSecurite->setModel(criteresModele);
    ui->comboBoxCriteresSecurite->setModelColumn(criteresModele->fieldIndex("critere"));
    
    evenementsRedoutesModele->setFilter(QString("id_critere ="
                                                "(SELECT id FROM crit WHERE critere = '%1')").arg(ui->comboBoxCriteresSecurite->currentText()));
    ui->tableViewEvents->setModel(events);
    ui->tableViewEvents->hideColumn(0);
    ui->tableViewEvents->hideColumn(1);
    ui->tableViewEvents->setItemDelegate(new 
    QSqlRelationalDelegate(ui->tableViewEvents));
    connect(ui->comboBoxCriteresSecurite, SIGNAL(currentTextChanged(QString)), this, SLOT(slot_refreshCritSec()));
    
    void slot_refreshCritSec()
    {
        evenetsModele->setFilter(QString("id_critere ="
                                                    "(SELECT id FROM crit WHERE critere = '%1')").arg(string));
    
        ui->tableViewEvenets->reset();
        eventsModele->setRelation(3, QSqlRelation(normalized, "id", "niveau"));
        eventsModele->select();
        ui->tableViewEvents->setItemDelegate(new QSqlRelationalDelegate(ui->tableViewEvents));
    }
    

    The first question is : Is it possible to manage multiple QAbstractItemDelegate for the same column ?
    If yes, how ?

    1 Reply Last reply
    0
    • SGaistS Offline
      SGaistS Offline
      SGaist
      Lifetime Qt Champion
      wrote on last edited by
      #2

      Hi,

      You can change the delegate at any time.

      However, when one wants to have a flexible delegate, he usually builds one that is capable of handling different type of data or load different sets of data into the editor depending on whatever the conditions are.

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

      1 Reply Last reply
      2
      • E Offline
        E Offline
        EagleWatch
        wrote on last edited by
        #3

        Hi @SGaist,

        What's a flexible delegate ?
        I'm not sure to understand correctly.

        mrjjM 1 Reply Last reply
        0
        • E EagleWatch

          Hi @SGaist,

          What's a flexible delegate ?
          I'm not sure to understand correctly.

          mrjjM Offline
          mrjjM Offline
          mrjj
          Lifetime Qt Champion
          wrote on last edited by mrjj
          #4

          @EagleWatch
          Its just a more feature full version of the Delegate. Or you could call it data driven.

          When its time to edit the data, the frameworks calls
          QWidget *MyDelegate::createEditor(QWidget *parent,
          const QStyleOptionViewItem &option,
          const QModelIndex &index) const

          Here you can use a flag, a user role or whatever fits to instruct to create a combobox
          and not LineEdit or what is needed.

          Same applies when writing data back, it must also handle the various Widgets that could be created.
          That way same delegate can be used in various conditions.
          There is ofcourse a fine line of having a monster Delegate or splitting it to multiple ones but in most cases
          handling a few different editors etc is super fine.

          1 Reply Last reply
          2
          • E Offline
            E Offline
            EagleWatch
            wrote on last edited by EagleWatch
            #5

            @mrjj
            Here is how my program looks like.
            0_1525943271361_editor.png

            So I can create an editor for each filter I want ?
            When can I call the editor I want ? The combobox used to filter what the editor shows is edited dynamically. I'm afraid I have to create an editor each time I select an item, but what about the memory ?

            EDIT : With the code I provided, here is what's happening
            0_1525944018845_Capture.JPG
            When the I change the filter (by choosing another item in the combobox), the editor is fine.

            Howerver, when I double click to change the value, the editor is filtered with the first filter I initialized.
            0_1525944231511_Capture.JPG

            1 Reply Last reply
            0
            • SGaistS Offline
              SGaistS Offline
              SGaist
              Lifetime Qt Champion
              wrote on last edited by
              #6

              Something is not completely clear with your setup.

              Do you mean the content of the combo box above the table view depends on the what you selected in one of the rows of said tableview ?

              Or that the content of the cell editor depends on what you selected in the combo box above the table view ?

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

              1 Reply Last reply
              1
              • E Offline
                E Offline
                EagleWatch
                wrote on last edited by
                #7

                The content of the cell editor should depends on what I select in the combobox above the table view.

                And the content in the combobox above the table view depends on another table view not important here.

                mrjjM 1 Reply Last reply
                0
                • E EagleWatch

                  The content of the cell editor should depends on what I select in the combobox above the table view.

                  And the content in the combobox above the table view depends on another table view not important here.

                  mrjjM Offline
                  mrjjM Offline
                  mrjj
                  Lifetime Qt Champion
                  wrote on last edited by
                  #8

                  @EagleWatch
                  hi
                  but why you need a new Delegate for that ?
                  Could you not just change what ever combobox is using ?
                  Like via a slot in Delegate and a signal from mainwindow.

                  1 Reply Last reply
                  0
                  • E Offline
                    E Offline
                    EagleWatch
                    wrote on last edited by
                    #9

                    @mrjj
                    Hi,

                    That would be better, but I didn't find how I could do that.

                    mrjjM 1 Reply Last reply
                    0
                    • E EagleWatch

                      @mrjj
                      Hi,

                      That would be better, but I didn't find how I could do that.

                      mrjjM Offline
                      mrjjM Offline
                      mrjj
                      Lifetime Qt Champion
                      wrote on last edited by
                      #10

                      @EagleWatch
                      well easy option is just keep Delegate pointer
                      around and simply add a new function to it to update List
                      via the instance pointer.

                      Alternatively add a new slot in Delegate
                      void ChangeList(QList<xx> list)
                      (should store list for use when editor is created)

                      and a new signal in mainwindow
                      ( that looks the same)
                      and connect them and simple use emit to update the combobox.

                      E 1 Reply Last reply
                      0
                      • mrjjM mrjj

                        @EagleWatch
                        well easy option is just keep Delegate pointer
                        around and simply add a new function to it to update List
                        via the instance pointer.

                        Alternatively add a new slot in Delegate
                        void ChangeList(QList<xx> list)
                        (should store list for use when editor is created)

                        and a new signal in mainwindow
                        ( that looks the same)
                        and connect them and simple use emit to update the combobox.

                        E Offline
                        E Offline
                        EagleWatch
                        wrote on last edited by EagleWatch
                        #11

                        @mrjj
                        That was one of my ideas but I think I don't understand how the delagate works.

                        When I study the QSqlRelationnalDelegate, I know the combobox is created with the createEditor function.
                        However, I don't understand how to modify the item in the combobox when the editor already exists.

                        I think I shoud use the function setEditorData but how to get the editor and the index I have to pass to this function ?

                        mrjjM 1 Reply Last reply
                        0
                        • E EagleWatch

                          @mrjj
                          That was one of my ideas but I think I don't understand how the delagate works.

                          When I study the QSqlRelationnalDelegate, I know the combobox is created with the createEditor function.
                          However, I don't understand how to modify the item in the combobox when the editor already exists.

                          I think I shoud use the function setEditorData but how to get the editor and the index I have to pass to this function ?

                          mrjjM Offline
                          mrjjM Offline
                          mrjj
                          Lifetime Qt Champion
                          wrote on last edited by
                          #12

                          Hi
                          Sorry i miss the fact that you use a standard Delegate
                          QSqlRelationalDelegate
                          and not a custom one.
                          I think you need to make a small subclass of QSqlRelationnalDelegate
                          and override createEditor so you can adjust whats to happen.

                          Since you can call the baseclass's QWidget *QSqlRelationalDelegate::createEditor
                          and get the Editor back. the (QWidget *) you can use qobject_cast to convert to
                          combobox and hence adjust its items.

                          But Maybe this is overkill. I would wait and see if others have easier ideas.

                          E 1 Reply Last reply
                          0
                          • mrjjM mrjj

                            Hi
                            Sorry i miss the fact that you use a standard Delegate
                            QSqlRelationalDelegate
                            and not a custom one.
                            I think you need to make a small subclass of QSqlRelationnalDelegate
                            and override createEditor so you can adjust whats to happen.

                            Since you can call the baseclass's QWidget *QSqlRelationalDelegate::createEditor
                            and get the Editor back. the (QWidget *) you can use qobject_cast to convert to
                            combobox and hence adjust its items.

                            But Maybe this is overkill. I would wait and see if others have easier ideas.

                            E Offline
                            E Offline
                            EagleWatch
                            wrote on last edited by
                            #13

                            @mrjj
                            Hi,

                            I've thinking about what you said and I tried to create a subclass of QSqlRelationnalDelegate to get Editor back via the createEditor function.

                            However the createEditor function is protected, so I cannot override it.
                            I have no clue to get Editor back without create my own delegate class.

                            As others have not easier ideas, what you suggests might the best for the moment.

                            So , how can I override the createEditor function if this is protected ?

                            mrjjM 1 Reply Last reply
                            0
                            • E EagleWatch

                              @mrjj
                              Hi,

                              I've thinking about what you said and I tried to create a subclass of QSqlRelationnalDelegate to get Editor back via the createEditor function.

                              However the createEditor function is protected, so I cannot override it.
                              I have no clue to get Editor back without create my own delegate class.

                              As others have not easier ideas, what you suggests might the best for the moment.

                              So , how can I override the createEditor function if this is protected ?

                              mrjjM Offline
                              mrjjM Offline
                              mrjj
                              Lifetime Qt Champion
                              wrote on last edited by mrjj
                              #14

                              @EagleWatch
                              Hi
                              Whats wrong with

                              #include <QtSql/QSqlRelationalDelegate>
                              class MySQLDelegate : QSqlRelationalDelegate {
                              protected:
                                  virtual QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const override
                                  {
                                      QSqlRelationalDelegate::createEditor(parent,option,index);// call base
                                  }
                                  virtual void setEditorData(QWidget *editor, const QModelIndex &index) const override
                                  {
                                  }
                              };
                              
                              E 1 Reply Last reply
                              0
                              • mrjjM mrjj

                                @EagleWatch
                                Hi
                                Whats wrong with

                                #include <QtSql/QSqlRelationalDelegate>
                                class MySQLDelegate : QSqlRelationalDelegate {
                                protected:
                                    virtual QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const override
                                    {
                                        QSqlRelationalDelegate::createEditor(parent,option,index);// call base
                                    }
                                    virtual void setEditorData(QWidget *editor, const QModelIndex &index) const override
                                    {
                                    }
                                };
                                
                                E Offline
                                E Offline
                                EagleWatch
                                wrote on last edited by
                                #15

                                @mrjj

                                I don't get it. Maybe I need to study a little more in C++.

                                That would be what I would like to get :

                                #include <QtSql/QSqlRelationalDelegate>
                                class MySQLDelegate : QSqlRelationalDelegate {
                                protected:
                                    virtual QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const override
                                    {
                                        editor = QSqlRelationalDelegate::createEditor(parent,option,index);// call base
                                    }
                                    virtual void setEditorData(QWidget *editor, const QModelIndex &index) const override
                                    {
                                    }
                                
                                private:
                                    QWidget *editor;
                                };
                                

                                Of course, the code will not work because of the "const" word.

                                mrjjM 1 Reply Last reply
                                0
                                • E EagleWatch

                                  @mrjj

                                  I don't get it. Maybe I need to study a little more in C++.

                                  That would be what I would like to get :

                                  #include <QtSql/QSqlRelationalDelegate>
                                  class MySQLDelegate : QSqlRelationalDelegate {
                                  protected:
                                      virtual QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const override
                                      {
                                          editor = QSqlRelationalDelegate::createEditor(parent,option,index);// call base
                                      }
                                      virtual void setEditorData(QWidget *editor, const QModelIndex &index) const override
                                      {
                                      }
                                  
                                  private:
                                      QWidget *editor;
                                  };
                                  

                                  Of course, the code will not work because of the "const" word.

                                  mrjjM Offline
                                  mrjjM Offline
                                  mrjj
                                  Lifetime Qt Champion
                                  wrote on last edited by mrjj
                                  #16

                                  @EagleWatch
                                  ahh, the const.
                                  well you dont need to store the Editor as its given in
                                  setEditorData(QWidget *editor, const QModelIndex &index) const {
                                  QComboBox *cb=qobject_cast<QComboBox *>(editor);
                                  if (cb) {
                                  use combo...
                                  }

                                  // handle other types of widgets or send to base setEditorData

                                  }

                                  E 1 Reply Last reply
                                  1
                                  • mrjjM mrjj

                                    @EagleWatch
                                    ahh, the const.
                                    well you dont need to store the Editor as its given in
                                    setEditorData(QWidget *editor, const QModelIndex &index) const {
                                    QComboBox *cb=qobject_cast<QComboBox *>(editor);
                                    if (cb) {
                                    use combo...
                                    }

                                    // handle other types of widgets or send to base setEditorData

                                    }

                                    E Offline
                                    E Offline
                                    EagleWatch
                                    wrote on last edited by
                                    #17

                                    @mrjj
                                    Hi,
                                    I get it, thank you.
                                    The setEditorData(QWidget *editor, const QModelIndex &index) const {} is protected so I cannot override it.

                                    delegate.h:18: error : 'virtual void Delegate::setEditorData(QWidget*, const QModelIndex&) const' is protected
                                         virtual void setEditorData(QWidget *editor, const QModelIndex &index) const
                                                      ^
                                    

                                    This function is not present in the QSqlRelationnalDelegate class.
                                    Maybe I have to subclass QItemDelegate instead ?

                                    mrjjM 1 Reply Last reply
                                    0
                                    • E EagleWatch

                                      @mrjj
                                      Hi,
                                      I get it, thank you.
                                      The setEditorData(QWidget *editor, const QModelIndex &index) const {} is protected so I cannot override it.

                                      delegate.h:18: error : 'virtual void Delegate::setEditorData(QWidget*, const QModelIndex&) const' is protected
                                           virtual void setEditorData(QWidget *editor, const QModelIndex &index) const
                                                        ^
                                      

                                      This function is not present in the QSqlRelationnalDelegate class.
                                      Maybe I have to subclass QItemDelegate instead ?

                                      mrjjM Offline
                                      mrjjM Offline
                                      mrjj
                                      Lifetime Qt Champion
                                      wrote on last edited by
                                      #18

                                      @EagleWatch

                                      Hi, im missing something. following code compiles with no
                                      remarks. its listed under protected and im not sure what goes wrong in your case.

                                      #include <QtSql/QSqlRelationalDelegate>
                                      class MySQLDelegate : QSqlRelationalDelegate {
                                      protected:
                                          virtual QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const override
                                          {
                                              QSqlRelationalDelegate::createEditor(parent,option,index);// call base
                                          }
                                          virtual void setEditorData(QWidget *editor, const QModelIndex &index) const override
                                          {
                                          }
                                      };
                                      
                                      E 1 Reply Last reply
                                      0
                                      • mrjjM mrjj

                                        @EagleWatch

                                        Hi, im missing something. following code compiles with no
                                        remarks. its listed under protected and im not sure what goes wrong in your case.

                                        #include <QtSql/QSqlRelationalDelegate>
                                        class MySQLDelegate : QSqlRelationalDelegate {
                                        protected:
                                            virtual QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const override
                                            {
                                                QSqlRelationalDelegate::createEditor(parent,option,index);// call base
                                            }
                                            virtual void setEditorData(QWidget *editor, const QModelIndex &index) const override
                                            {
                                            }
                                        };
                                        
                                        E Offline
                                        E Offline
                                        EagleWatch
                                        wrote on last edited by EagleWatch
                                        #19

                                        @mrjj
                                        I get the error only when I'm using the MySqlDelegate.

                                        So, in my projectWindow.h, if I have :

                                        #include "mysqldelegate.h"
                                        private:
                                            MySqlDelegate *m_delegate;
                                        

                                        I get the issue in the MySqlDelegate class.

                                        Do you get the issue if you call your class ?

                                        1 Reply Last reply
                                        0
                                        • SGaistS Offline
                                          SGaistS Offline
                                          SGaist
                                          Lifetime Qt Champion
                                          wrote on last edited by
                                          #20

                                          Hi,

                                          Can you show how you are using it ?

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

                                          E 1 Reply Last reply
                                          1

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