比较对象并在列表中搜索 [英] Compare objects and search in list

问题描述

我使用 Python 3 和 PySide2(Qt for Python)(都是最新的).我有一个 PySide2 对象列表，必须检查列表中是否存在一个项目.如果我尝试这样做，我会收到错误:

I use Python 3 and PySide2 (Qt for Python) (both up to date). I have a list of PySide2 objects and have to check if an item exists in the list. If I try to do this, I get the error:

NotImplementedError: operator not implemented.

from PySide2 import QtGui
item = QtGui.QStandardItem()
item1 = QtGui.QStandardItem()

item == item1 # creates error

list1 = [item, item1]
item1 in list1 # creats error

我做错了什么?我怎样才能做到这一点?我必须自己实现=="运算符吗?预先感谢您的帮助！

What do I wrong? How can I do this? Do I have to implement the "==" operator myself? Thank you in advance for your help!

推荐答案

如评论中所述，您得到的错误是 bug 是 PySide 的残余.

As noted in a comment, the error you get is part of a bug that is remnants of PySide.

我认为您有一个 XY 问题，您想要检查是否有带有预定义文本.如果是这样，则不需要实现运算符 == 而是使用 findItems() 方法:

I think that you have an XY problem, and what you want is to check if there is an item with a predefined text. If so, it is not necessary to implement the operator == but use the findItems() method:

from PySide2 import QtCore, QtGui

if __name__ == "__main__":
    import sys

    md = QtGui.QStandardItemModel()
    for text in ("Hello", "Stack", "Overflow"):
        md.appendRow(QtGui.QStandardItem(text))

    words = ("Hello", "World")

    for word in words:
        if md.findItems(word, flags=QtCore.Qt.MatchExactly, column=0):
            print(f"{word} exists")
        else:
            print(f"{word} not exists")

或者如果你想使用 match() 方法搜索其他角色:

Or use the match() method if you want to search for some other role:

from PySide2 import QtCore, QtGui

FooRole = QtCore.Qt.UserRole + 1000

if __name__ == "__main__":
    import sys

    md = QtGui.QStandardItemModel()
    for i, text in enumerate(("Hello", "Stack", "Overflow")):
        it = QtGui.QStandardItem(str(i))
        it.setData(text, FooRole)
        md.appendRow(it)

    words = ("Hello", "World")

    for word in words:
        if md.match(
            md.index(0, 0), FooRole, word, hits=1, flags=QtCore.Qt.MatchExactly
        ):
            print(f"{word} exists")
        else:
            print(f"{word} not exists")

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