Cascades Development

[BrandonO]

In my C++ files I have a QMap of data that I would like to add to a DropDown that I have in QML.

I can't find any examples of how to add options to an already existing DropDown though.  Here's what I have in my QML file right now:

DropDown {
                    id: account
                    title : "Account"
                    enabled : true
                }

 It seems like it should be a fairly easy process to get the DropDown list by the id and insert data from my QMap into it.

Any help with this would be greatly appreciated!

[chriske86]

Hi,

in the class reference is a C++ example:
https://developer.blackberry.com/cascades/reference/bb__cascades__dropdown.html

If you need more help, there is a sample application in github, where every UI controller is presented in C++:

https://github.com/blackberry/Cascades-Samples/tree/master/cascadescookbookcpp

[BrandonO]

The class reference it isn't populating an existing DropDown. It's creating a new one entirely in C++.

I don't want to build the entire QML structure in C++, I'd rather write the QML code out and then populate the DropDown with data after the fact.

I haven't come across any easy way to do this though.

[chriske86 · Accepted solution]

Oh, I did not see, that you don't know how to connect the C++ logic to the QML UI, The QML component ID is not enough, you must define objectName: "dropDown" property too.

You can reach any QML object from cpp like this:

//this snippet is from YourProjectName.cpp
// create scene document from main.qml asset
// set parent to created document to ensure it exists for the whole
// application lifetime

QmlDocument *qml = QmlDocument::create("asset:///main.qml").parent(this);

// create root object for the UI
AbstractPane *root = qml->createRootObject<AbstractPane>();
// set created root object as a scene
app->setScene(root);

//and here comes the findChild method
DropDown* dpList = root->findChild<DropDown*>("dropDown");

After this line, dpList will point to the UI controller.

[BrandonO]

I marked your previous message as the Solution but I'm actually still having problems. Apparently you can't use findChild on an AbstractPane.

I get the following error:
no matching function for call to 'bb::cascades::AbstractPane::findChild(const char [9])'

[Zmey]

Hi,

Can you please show how do you call findChild? It's a template function. The following forms should work:

AbstractPane *root = qml->createRootObject<AbstractPane>();

QObject *button = root->findChild<QObject *>("button");
or
Container *container = root->findChild<Container *>("rootContainer");

Is the following line present in .cpp?

#include <bb/cascades/AbstractPane>

UPD:

I've checked that this function is actually defined in QObject and AbstractPane inherits QObject. I was able to compile the following code:

#include <bb/cascades/AbstractPane>
...
bb::cascades::AbstractPane *pane;
pane->findChild<QObject *>("test");

[BrandonO]

Zmey, It works with QObject but there's no add() function on a QObject to add items to the DropDown... which is the whole point of this.

Maybe I'm going about this wrong, but all I want is to get a DropDown populated with dynamic data that I can't hardcode into it. It seems like this should be a very trivial task.

If there's a better way to do this, please let me know.

[Zmey]

This should work I think:

#include <bb/cascades/AbstractPane>
#include <bb/cascades/DropDown>

using namespace bb::cascades;

...

DropDown *dropDown = pane->findChild<DropDown *>("account");
dropDown->add(Option::create().text("Option 1"));