Populating comboBox with the first column of layer table attribute using PyQGIS

Question

I am new to Python and QGIS. I want to populate the comboBox with the first column of the table attribute of the park's layer

Code:

 #Populate park's comboBox
 park = layers[0].layer()
 park.startEditing()
 for p in park.getFeatures():
 self.dlg.comboBox_2.addItem(p.attributes()[0])

Error:

2022年01月03日T01:39:23 WARNING Traceback (most recent call last):

File "C:/Users/ADS/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\urban_parks\urban_parks.py", line 217, in run

self.dlg.comboBox_2.addItem(p.attributes()[0]) TypeError: arguments did not match any overloaded call: addItem(self, str, userData: Any = None): argument 1 has unexpected type 'int'

addItem(self, QIcon, str, userData: Any = None): argument 1 has unexpected type 'int'

• Llaves: if you're just going to enumerate the park layer's features to populate the comboBox you don't need to call startEditing. In fact, you probably should avoid it.
• PolyGeo: Welcome to GIS SE! As a new user be sure to take the Tour to learn about our focussed Q&A format. You appear to have created two accounts which inevitably leads to a frustrating experience for you, potential answerers and reviewers so please follow these instructions ASAP to merge your accounts.

Answer 1

The problem is that the feature attributes which you are trying to add to your combo box are evidently of an integer datatype. The addItem() method of QComboBox expects a string argument.

Therefore, you need to cast the attribute value argument to a string:

...
for p in park.getFeatures():
 self.dlg.comboBox_2.addItem(str(p.attributes()[0]))
...

• Llaves: You will also need to remember that when you fetch the selected value from the combo box, it will be returned as a string. To be consistent with the type in the attribute, you will want to convert it back to an int using the int() function.