PyQt4-QGIS表单错误

Question

I've to build a form in QGIS to customize data input for each polygon in the shapefile. I use QtDesigner to create a form (.ui), with some textboxes and comboboxes pointing to the fields of my shapefile.
Then I use the python file from Nathan QGIS Blog to add some logic.

Python code:

from PyQt4.QtCore import *
from PyQt4.QtGui import *

nameField = None
myDialog = None

def formOpen(dialog,layerid,featureid):
    global myDialog
    myDialog = dialog
    global nameField
    nameField = dialog.findChild(QTextEdit,"PART")
    buttonBox = dialog.findChild(QDialogButtonBox,"buttonBox")

    nameField.textChanged.connect(Name_onTextChanged)

    # Disconnect the signal that QGIS has wired up for the dialog to the button box.
    buttonBox.accepted.disconnect(myDialog.accept)

    # Wire up our own signals.
    buttonBox.accepted.connect(validate)
    buttonBox.rejected.connect(myDialog.reject)

def validate():
    # Make sure that the name field isn't empty.
    if not nameField.text().length() > 0:
        nameField.setStyleSheet("background-color: rgba(255, 107, 107, 150);")
        msgBox = QMessageBox()
        msgBox.setText("Field PART must not be NULL.")
        msgBox.exec_()
    else:
        # Return the form as accpeted to QGIS.
        myDialog.accept()

def Name_onTextChanged(text):
    if not nameField.text().length() > 0:
        nameField.setStyleSheet("background-color: rgba(255, 107, 107, 150);")
    else:
        nameField.setStyleSheet("")

So I open an edit session in QGIS and I click on a polygon with Identify tool, but when I clik on OK button on my customized form, regardless field PART is NULL or not, the following error occurs:

ERROR CODE LINE >>>> if not nameField.text().length() > 0:
ERROR MESSAGE   >>>> AttributeError: 'str' object has no attribute 'text'

I'm running QGIS 1.7.4, Python 2.7.2, Windows 7 64-bit.
I miss something... Please, anybody can help me?

Answer 1

It looks like you have a Python error more than a problem with QGIS.

You have two instances of if not nameField.text().length() > 0:

def validate():
    if not nameField.text().length() > 0:

and

def Name_onTextChanged(text):
    if not nameField.text().length() > 0:

Initially, it looks like nameField is not an input for either of these functions. So I guess these are assigned somewhere else and you've reduced the code example. Also, you have text as a variable input for 'Name_onTextChanged' but you also try and use it as a function 'nameField.text().length()'. This might be a problem.

Generally, Python is complaining because it cannot perform the operation 'text()' on the variable nameField, which it believes is a string. There is no text() function available for strings . And it looks like nameField is actually supposed to be a QTextEdit object.

If nameField is a QTextEdit object, then you can use toPlainText() instead which should do what you need it to do. So something like

if not nameField.toPlainText().strip().length() > 0:

In this instance, I have included .strip() as well so that you do not get a positive result if there are white spaces in text field.

Does that help at all?