PyQt5可过滤ComboBox问题：仅匹配开头，无法匹配字符串内部

我刚接触Python，之前学过Cobol和Pascal，可能有些旧习惯。我使用Python 3.11和PyQt5实现了一个FilterComboBox类，期望用户输入时，只要输入文本匹配下拉框选项的任意部分就进行过滤，但当前代码仅在匹配选项开头时生效，无法匹配字符串内部的内容。

原代码：

class FilterComboBox(QtWidgets.QComboBox):
    def __init__(self, parent=None):
        super(FilterComboBox, self).__init__(parent)
        self.setFocusPolicy(QtCore.Qt.StrongFocus)
        self.setEditable(True)

        # add a filter model to filter matching items
        self.pFilterModel = QtCore.QSortFilterProxyModel(self)
        self.pFilterModel.setFilterCaseSensitivity(QtCore.Qt.CaseInsensitive)

        # add a completer, which uses the filter model
        self.completer = QtWidgets.QCompleter(self.pFilterModel, self)
        # filter the completions
        self.completer.setCompletionMode(QtWidgets.QCompleter.PopupCompletion)
        self.setCompleter(self.completer)

        # connect signals
        self.lineEdit().textEdited.connect(self.on_lineEdit_textEdited)
        self.completer.activated.connect(self.on_completer_activated)

    def on_lineEdit_textEdited(self, text):
        regex = QtCore.QRegExp(".*" + text + ".*", QtCore.Qt.CaseInsensitive, QtCore.QRegExp.RegExp)
        self.pFilterModel.setFilterRegExp(regex)

    # on selection of an item from the completer, select the corresponding item from combobox 
    def on_completer_activated(self, text):
        if text:
            index = self.findText(text)
            self.setCurrentIndex(index)
            self.activated[str].emit(self.itemText(index))

    # on model change, update the models of the filter and the completer as well 
    def setModel(self, model):
        super(FilterComboBox, self).__init__(parent)
        self.setFocusPolicy(QtCore.Qt.StrongFocus)
        self.setEditable(True)

        # add a filter model to filter matching items
        self.pFilterModel = QtCore.QSortFilterProxyModel(self)
        self.pFilterModel.setFilterCaseSensitivity(QtCore.Qt.CaseInsensitive)

        # add a completer, which uses the filter model
        self.completer = QtWidgets.QCompleter(self.pFilterModel, self)
        # filter the completions
        self.completer.setCompletionMode(QtWidgets.QCompleter.PopupCompletion)
        self.setCompleter(self.completer)

        # connect signals
        self.lineEdit().textEdited.connect(self.on_lineEdit_textEdited)
        self.completer.activated.connect(self.on_completer_activated)

    def on_lineEdit_textEdited(self, text):
        regex = QtCore.QRegExp(".*" + text + ".*", QtCore.Qt.CaseInsensitive, QtCore.QRegExp.RegExp)
        self.pFilterModel.setFilterRegExp(regex)

    # on selection of an item from the completer, select the corresponding item from combobox 
    def on_completer_activated(self, text):
        if text:
            index = self.findText(text)
            self.setCurrentIndex(index)
            self.activated[str].emit(self.itemText(index))

    # on model change, update the models of the filter and the completer as well 
    def setModel(self, model):
        super(FilterComboBox, self).setModel(model)
        self.pFilterModel.setSourceModel(model)
        self.completer.setModel(self.pFilterModel)

    # on model column change, update the model column of the filter and completer as well
    def setModelColumn(self, column):
        self.completer.setCompletionColumn(column)
        self.pFilterModel.setFilterKeyColumn(column)
        super(FilterComboBox, self).setModelColumn(column)

问题根源是QSortFilterProxyModel默认过滤模式为FilterFixedString，即使传入正则表达式，它也会把正则当成普通字符串处理，导致只有开头匹配才生效。需要明确设置过滤模式为正则匹配，并优化正则写法避免特殊字符干扰。

修改点： #

1. 初始化pFilterModel时，新增两行配置：
   • 设置过滤角色为显示文本，确保过滤的是选项的显示内容
   • 明确设置过滤模式为正则表达式匹配
2. 对用户输入的文本做正则转义，避免输入.、*等特殊字符破坏正则规则

修改后的完整代码： #

class FilterComboBox(QtWidgets.QComboBox):
    def __init__(self, parent=None):
        super(FilterComboBox, self).__init__(parent)
        self.setFocusPolicy(QtCore.Qt.StrongFocus)
        self.setEditable(True)

        # add a filter model to filter matching items
        self.pFilterModel = QtCore.QSortFilterProxyModel(self)
        self.pFilterModel.setFilterCaseSensitivity(QtCore.Qt.CaseInsensitive)
        # 新增：设置过滤角色为显示文本，明确使用正则模式过滤
        self.pFilterModel.setFilterRole(QtCore.Qt.DisplayRole)
        self.pFilterModel.setFilterMode(QtCore.QSortFilterProxyModel.FilterRegExp)

        # add a completer, which uses the filter model
        self.completer = QtWidgets.QCompleter(self.pFilterModel, self)
        # filter the completions
        self.completer.setCompletionMode(QtWidgets.QCompleter.PopupCompletion)
        self.setCompleter(self.completer)

        # connect signals
        self.lineEdit().textEdited.connect(self.on_lineEdit_textEdited)
        self.completer.activated.connect(self.on_completer_activated)

    def on_lineEdit_textEdited(self, text):
        # 转义正则特殊字符，避免用户输入干扰
        escaped_text = QtCore.QRegExp.escape(text)
        regex = QtCore.QRegExp(f".*{escaped_text}.*", QtCore.Qt.CaseInsensitive, QtCore.QRegExp.RegExp)
        self.pFilterModel.setFilterRegExp(regex)

    # on selection of an item from the completer, select the corresponding item from combobox 
    def on_completer_activated(self, text):
        if text:
            index = self.findText(text)
            self.setCurrentIndex(index)
            self.activated[str].emit(self.itemText(index))

    # on model change, update the models of the filter and the completer as well 
    def setModel(self, model):
        super(FilterComboBox, self).setModel(model)
        self.pFilterModel.setSourceModel(model)
        self.completer.setModel(self.pFilterModel)

    # on model column change, update the model column of the filter and completer as well
    def setModelColumn(self, column):
        self.completer.setCompletionColumn(column)
        self.pFilterModel.setFilterKeyColumn(column)
        super(FilterComboBox, self).setModelColumn(column)

内容的提问来源于stack exchange，提问作者Bikitsos