How to keep updating qml text object from python backend

Question

I am trying to update some sensor values posted to firebase using QT qml with python as the backend. The values come from different sensors so I'm using a QStandardItemModel and a for loop to iterate through a fetch-link function. For now, the GUI only displays the current value it gets from the server and doesn't update.

python function to get the firebase link. (3 of these for each parameter)

def fetch_p(self, current_node):
    node_id = ('/00' + str(current_node) + '/p')
    node_data = firebase.FirebaseApplication('https://link/', None)
    result = node_data.get(node_id, None)
    return result

Code for QT model

def __init__(self):
    super().__init__()
    self._model = QStandardItemModel()
    self._model.setItemRoleNames({Qt.DisplayRole: b"custom_name"})

For loop to create the model items

for i in range(1, 4):
    node_id = ("Node 00" + str(i))
    pPower = bridge.fetch_p(i)
    pAng_y = bridge.fetch_y(i)
    pAng_z = bridge.fetch_z(i)
    bridge.add_node_card(node_id)

I think the codes above should provide an overview of what I've done. the overall code is lengthy and messy as I am so inexperienced.

what I am having challenges with getting the GUI to keep updating values continuously. I tried using the while loop before the for loop but the app wouldn't launch (loading circle). I have also searched online and found out that this could be best done using Qthread but I'm too inexperienced to implement the codes I found in my program. Finaly, I think it's important I talk about the QMl files. I have a main.qml and a nodecard.qml. the nodecard.qml is created using the ItemModel.

Repeater{
          model: backend.model
          NodeCard{
             id: thisCard
             text: model.custom_name
             power: backend.powerUpdate()
             yAng: backend.tiltAngleY()
             zAng: backend.tiltAngleZ()
             priority: backend.priorLevel()
           }

Preview of what the GUI looks like

Any form of help or guidance will be much appreciated.

score 0 · Answer 1 · answered Feb 18 '22 at 05:16

I'm not familiar with python or firebase,here is my suggestions:

what I am having challenges with getting the GUI to keep updating values continuously. I tried using the while loop before the for loop but the app wouldn't launch (loading circle). I

I suggest learn what is an event loop What is an event loop in Qt?

I have also searched online and found out that this could be best done using Qthread

Try using QTimer if function call firebase.FirebaseApplication('https://link/', None)returns quickly. Timer is easier than thread

How to keep updating qml text object from python backend

1 Answers1