accessing elements of a ListModel

mzimmers

@fcarney said in accessing elements of a ListModel:

Are you taking data from 2 sources?

Yes I am: I have the positions and dimensions in a QML ListModel. The "real" information about the bottle (size, contents, expiration date, etc) comes from a view model.

If so you can build up a ListModel and combine multiple sources of data using a function. Then use that model as the model for your repeater.

I like the sound of this. How do I put this in a loop, so I don't have to do something like this?

  ListModel {
    id: bottleModel_19

    ListElement {
      // position 1
      x: 407
      y: 18
      height: 78
      width: 78
      bottleLabel: (reagentManager.bottleList[index] !== undefined)
                   ? reagentManager.bottleList[index].name
                   : "ETH"
    }
    ...

fcarney

No, use the methods for ListModel like insert.

onChangeOfSourceList: {
  bottleModel_19.clear()
  for(var count=0; count<x; ++count){ 
    // insert, get, and set use js objects
    bottleModel_19.insert(count, {
      "x":list1[count].whatever,
      ...  // repeat for items from both lists
    })
  }
}

Edit: Maybe append is better. Also clear list each time you recreate the list.

mzimmers

Does onChangeOfSourceList correspond to the signal I emit when I've updated the list? Here's my property:

  Q_PROPERTY(Bottles bottleList
                 MEMBER m_bottleList
                     NOTIFY bottleListChanged)

I tried onbottleListChanged, but this isn't correct.

fcarney

Yes, something that emits a signal that you are calling when you update lists.
It will be:

onBottleListChanged

Notice the B gets capitalized. Is there another signal that can trigger this too? Then you will need to create a function that gets called in each instance.

function updateListModel(){
  ...
}
onBottleListChanged: updateListModel()
onOtherListChanged: updateListModel()

mzimmers

@fcarney to which component is the onBottleListChanged: applied? I've tried putting this in several places in my QML file, and the editor warns of an invalid property name. Am I supposed to put this in a Connections object?

I don't have another signal for a bottle list update. Earlier you asked:

Are you taking data from 2 sources?

Yes I am. I put some data in the QML ListModels. This is data pertaining to the UI itself (screen location of the representation, size, etc.) "Real" data about the bottles (label, contents, fill level) is kept in a C++ object. This seemed like a natural breakdown for the data; is using two sources a bad idea?

Thanks...

fcarney

@mzimmers said in accessing elements of a ListModel:

Q_PROPERTY(Bottles bottleList
MEMBER m_bottleList
NOTIFY bottleListChanged)

What object has this in it?

mzimmers

@fcarney

class ReagentManager : public QObject {
  Q_OBJECT
 public:
  Q_PROPERTY(Bottles bottleList
                 MEMBER m_bottleList
                     NOTIFY bottleListChanged)
...
class ChangeConsumables : public QObject {
  Q_OBJECT
  ReagentManager m_reagentManager;
...
}
engine->rootContext()->setContextProperty("reagentManager", &m_reagentManager);

fcarney

@mzimmers said in accessing elements of a ListModel:

engine->rootContext()->setContextProperty("reagentManager", &m_reagentManager);

Then its a connection on the reagentManager.

mzimmers

@fcarney the reagentManager generates the signal, but who consumes it?

fcarney

onBottleListChanged: updateListModel()

You call the function that rebuilds your ListModel. Don't you want that to update when it changes? Also, you said you had two lists of data. Does it have a signal too?

mzimmers

@fcarney said in accessing elements of a ListModel:

onBottleListChanged: updateListModel()

Oh, OK...I see my problem now. I was trying to use this line of code from within the repeater. I see now that it should go in the containing Rectangle.

You call the function that rebuilds your ListModel. Don't you want that to update when it changes? Also, you said you had two lists of data. Does it have a signal too?

I have two sources of data: one in C++ and one in a QML ListModel. I actually have 2 QML ListModels, but only use one (which one to use is determined at runtime by an environment variable). The only signal is emitted by the C++ update function; nothing in the ListModels.

As it turns out, I've been able to eliminate the use of the QML update function entirely (though I still need the getColor routine() above, so I won't need to use this feature here, but this has been very educational. Thank you for all the help.