[Merged] Inheriting Ui::MainWindow to add QListWidgetItem to a give ListWidget

[goetz]

Sorry, I don't understand what you're trying to do. It sounds like you're doing it over complicated. If your business logic has 8000 lines, it hat 8000 lines of code - regardles if it is in one file or split over 20.

Adding an item is in my opinion a function that belongs to the list widget class (reps. the form that does contain the list widget). You should add method (probably as a slot) that you call with the relevant data and let the method create the list view item. That also has the advantage that you can change your implementation afterwards without the need to change all your other code.

Regarding the UI (classes):
A UI class generated with uic from a .ui file only does make sense and is functionable when you marry it with a QWidget, that's what setupUi() is for. If you don't call that, your UI is useless.

I'd suggest you make yourself comfortable with the principles of the uic generated classes first. Use Chapter "Using a Designer UI File in Your Application ":http://doc.qt.nokia.com/4.7/designer-using-a-ui-file.html of Qt Designer documentation as a starting point

And as an advice: Make it work correctly in the first place and do the optimizations afterwards. If you have a working application - made straight forward - it is often much easier to "beautify" it later.

[webmaster.skelton]

Thanks for the help, It just seems like QT makes it difficult for this sort of design. I know everything works as i originally had it that way to make sure it did. Ill figure out what i need eventually. Thanks

[tobias.hunger]

I would recommend keeping the UI class small by using signals, slots and accessors. Add signals for all the ui actions that are of interest and connect them to other objects implementing the business logic. Those can in turn trigger slots in the UI to trigger the changes you want. That way the internals of the UI stay in one class and you will not need to fix up code all over the place when you decide to rework the UI.

[tobias.hunger]

By the way: EventHandler has a well defined meaning in Qt. Are you using the term in a similar way? If not that might confuse Qt coders that will have to maintain the code later on:-)

[goetz]

I'm sure it can be done the way you intend to do it. But sometimes one just screws up everything. I've been bitten often enough :-) I usually start from scratch then.

Regarding your problem:
Of course you can create a list widget item with new in a separate class and add it to the ui of another class. But that couples the two classes tightly, which is not what you want most times, since one class needs to know the internals of the other. Maybe you decide to drop QListWidget in favor of QListView and specially design item model. You would have to change all your code!

It's usually better to send messages to the other class and ask it to do the desired task (using signals/slots in Qt). Since the actual implementation is not public in this case, you easily could do the refactoring I mentioned in the paragraph before.

Give it a try and you will get beautiful and easy to write and maintainable code :-)

[erapid]

Pure answer is that U call methods on uninitialised pointers.

Any form you create, throwing the widgets in the designer - just a collection of widgets. Try to open ui file in a text editor ;) ( But better don't save it in editor )

So, when UIC eats form file it produces a Collection class: set of pointers with two methods -
setupUi( Parent* ) and retranslateUi. Parent is QWidget in common case.

setupUI is a key! It creates and inits real widgets and sets them Parent as parent.

No setupUi - no real objects and then U'll get segfault in ui->txt_Medicaiton_MedicationName->text().

"See qt documentation":http://doc.qt.nokia.com/4.7/designer-using-a-ui-file.html

And Yes - UR code is strange
@
return listItem;

delete listItem;

delete ui;

MedicationButtonEventHandler::nextInstance++;

@
Do U catch that last three rows never runs?

[webmaster.skelton]

Ok so I am back now. After changing a few things around this is what i have ended up with:

@MedicationButtonHandler::MedicationButtonHandler(QWidget *parent) : QDialog(parent), ui(new Ui::EditMedicationForm) , mainUi(new Ui::MainForm)
{

ui->setupUi(this);

}

QListWidgetItem* MedicationButtonHandler::MedicationEdit_Add_Clicked()
{

MedicationButtonHandler::listItem = new QListWidgetItem(QIcon(":/img/medications.png"),

                                                ui->txt_Medication_Name->text()+ " - "+
                                                ui->txt_Medication_Dosage->text()+
                                                ui->cmb_Medication_Dosage->currentText()+ " - " +
                                                ui->txt_Medication_Quantity->text()+
                                                ui->cmb_Medication_Quantity->currentText()+" - " +
                                                ui->cmb_Medication_Administered->currentText()+ " - " +
                                                ui->txt_Medication_Frequency->text()+" - " +
                                                ui->txt_Medication_DateStarted->text()+ "-" +
                                                ui->txt_Medication_DateModified->text()+ " _ " +
                                                ui->txt_Medication_PrescribingDoctor->text()+ " - " +
                                                ui->txt_Medication_Pharmacy->text()+ " - " +
                                                ui-> txt_Medication_PharmacyPhone->text()+ " - " +
                                                ui-> txt_Medication_PrescriptionNum->text()
                                                ,mainUi->lst_Medication_List);


listItem->setFlags( Qt::ItemIsSelectable | Qt::ItemIsDragEnabled | Qt::ItemIsEnabled);

mainUi->lst_Medication_List->insertItem(nextInstance,listItem);



//delete listItem;






return listItem;

}

@

This still renders a seg fault even when i setup the Ui for the class.

@

[webmaster.skelton]

ok so here is the rundown, i simply wish to add a listItem to an exisisting listwidget on the mainform. This item needs to be added from another form called edit. When I actually try to connect the slots with the button clicked signal, I get a segfault. I am assuming it is because i can not access the mainForm widgets but I am not sure why. Here is some code.

Header:

@class MedicationButtonHandler : public QDialog , private Ui::EditMedicationForm , private Ui::MainForm
{

Q_OBJECT

public:
virtual ~MedicationButtonHandler();
static MedicationButtonHandler* GetInstance();

QListWidgetItem* listItem;

public slots:
QListWidgetItem * MedicationEdit_Add_Clicked();

void Medication_Delete_Clicked();

// QString* MedicationNotesClicked();

// void MedicationLearnMoreClicked();

// QString* MedicationFilesClicked();

// void MedicationDiscontinueClicked();

private:
MedicationButtonHandler(QWidget parent = 0);
static MedicationButtonHandler p_MedicationButtonHandler;
static int nextInstance;
Ui::EditMedicationForm *ui;
Ui::MainForm *mainUi;

};@

cpp:

@MedicationButtonHandler::MedicationButtonHandler(QWidget *parent) : QDialog(parent), ui(new Ui::EditMedicationForm) , mainUi(new Ui::MainForm)
{

ui->setupUi(this);

}

QListWidgetItem* MedicationButtonHandler::MedicationEdit_Add_Clicked()
{

MedicationButtonHandler::listItem = new QListWidgetItem(QIcon(":/img/medications.png"),

                                                ui->txt_Medication_Name->text()+ " - "+
                                                ui->txt_Medication_Dosage->text()+
                                                ui->cmb_Medication_Dosage->currentText()+ " - " +
                                                ui->txt_Medication_Quantity->text()+
                                                ui->cmb_Medication_Quantity->currentText()+" - " +
                                                ui->cmb_Medication_Administered->currentText()+ " - " +
                                                ui->txt_Medication_Frequency->text()+" - " +
                                                ui->txt_Medication_DateStarted->text()+ "-" +
                                                ui->txt_Medication_DateModified->text()+ " _ " +
                                                ui->txt_Medication_PrescribingDoctor->text()+ " - " +
                                                ui->txt_Medication_Pharmacy->text()+ " - " +
                                                ui-> txt_Medication_PharmacyPhone->text()+ " - " +
                                                ui-> txt_Medication_PrescriptionNum->text()
                                                ,lst_Medication_List);


listItem->setFlags( Qt::ItemIsSelectable | Qt::ItemIsDragEnabled | Qt::ItemIsEnabled);

mainUi->lst_Medication_List->insertItem(nextInstance,listItem);










return listItem;

}

@

I am not sure as to why this is not working,

[GordonSchumacher]

Well, first off, you should either inherit from your UI class, or include it as a pointer - not both.

Your call to ui->setupUi() is going to crash, because you have never initialized those ui or mainUi pointers.

[baysmith]

Remove the ui pointers and change the constructor to use
@
Ui::EditMedicationForm::setupUi(this);
Ui::MainForm::setupUi(this);
@

or

Remove the Ui::* inheritance and change the constructor to use
@
ui = new Ui::EditMedicationForm;
ui->setupUi(this);
mainUi = new Ui::MainForm;
mainUi->setupUi(this);
@

[erapid]

U didn't setup mainUi, so mainUi->lst_Medication_List is a pointer to nowhere

I'm sure Qt doesn't like to receive
@ new QListWidgetItem( const QIcon & icon, const QString & text, QListWidget * parent = 0, int type = Type )@ with broken parent

[goetz]

It is not intended that setupUi() of two different Ui classes are called with the main QWidget (this). At best the resulting Ui will look strange. I cannot see any use for this either.

You should have two classes, with .h and .cpp, for either EditMedicationForm and for MainForm.

Your call to mainUi->lst_Medication_List crashes, because you did not call setupUi on mainUi, so the members of mainUi are not yet created.

[webmaster.skelton]

Ok i understand that, but i need to be able to access and modify widgets located in two different UIs, For example, i have a list widget in main form and EditMedicationForm is where the attributes are changed. So I click add new, a new form pops up, I enter the information into the field, and i click save, those attributes need to be added to the listWidget located on main form. now am i wrong or do i not need to have access to both UI's to do this( fyi, I have tried handleing this in the editMedicationForm.cpp as well, i continue to get a seg fault because it will not let me setup the UI as it inherits from a QDialog, not a QMainWindow. Is there a better way to access and modify widgets located in multiple forms? I simply want to add a listwidget item to mainform from data created in editmedicationform. Am i thinking about the incorrectly?

[goetz]

[quote author="webmaster.skelton" date="1291900962"]Ok i understand that, but i need to be able to access and modify widgets located in two different UIs, For example, i have a list widget in main form and EditMedicationForm is where the attributes are changed. So I click add new, a new form pops up, I enter the information into the field, and i click save, those attributes need to be added to the listWidget located on main form.[/quote]

Make your ui/mainUi pointers public or declare the respective other class as friends. The members of the uic generated ui classes are public. So you can access them everywhere.

[quote author="webmaster.skelton" date="1291900962"]now am i wrong or do i not need to have access to both UI's to do this( fyi, I have tried handleing this in the editMedicationForm.cpp as well, i continue to get a seg fault because it will not let me setup the UI as it inherits from a QDialog, not a QMainWindow. Is there a better way to access and modify widgets located in multiple forms? I simply want to add a listwidget item to mainform from data created in editmedicationform. Am i thinking about the incorrectly?[/quote]

Be warned: it is common sense, that exposing implementation details to other classes (the ui elements add to that) is considered harmful. It is usually better that you have getters in your classes and forms (your QDialog based class to enter the data) to extract the data you need and provide them in an ui-independend form (Strings, numbers, maybe a small helper class/struct) and to provide a setter (slot) in the other class (MainForm) that does the task of adding the actual list item.

Also, you can not have widgets located in multiple forms! A widget belongs to either exactly one form (as a child widget) or no form at all (that holds for top level widgets like windows, dialogs, etc.)

Sorry, but I think you did not understand the whole concept about user interfaces, forms, widgets and that all. I strongly suggest you do some steps backwards and start with some tutorials and introductions to become comfortable with the basic design of Qt applications.

As a rule of thumb: one ui-file (Designer created form) goes together with exactly one header file (.h) and exactly one C++ implementation file (.cpp) and results in exactly one new custom widget. You can use the widget in other source files by including the header file. Whatever you made public in the class definition is available there.

[Franzk]

[quote author="Volker" date="1291902228"]As a rule of thumb: one ui-file (Designer created form) goes together with exactly one header file (.h) and exactly one C++ implementation file (.cpp) and results in exactly one new custom widget.[/quote]Agree. Only if you know exactly what you're doing you can somewhat deviate from this rule, however you should probably still step back and rethink your implementation.

[webmaster.skelton]

ok thanks for the help.

[troubalex]

Is the issue solved? Can I close the thread?

[goetz]

It should be merged with "this thread":http://developer.qt.nokia.com/forums/viewthread/2139/

[webmaster.skelton]

Yea it can be closed.