使用QCompleter时程序退出并出错

Question

I'm writing a program with pyqt5 and want to make the QlineEdit show history input by using sqlite to store the inputs. I use a signal to catch the cursor when focusInEvent happens and select the history records at that time, then I put the results into QCompleter so it can pop up in QlineEdit. Now I can make the history inputs show in QlineEdit object but when I click on any value, 1s later, the whole program quit automatically with error, which says "Python has stopped".

class FocusLineEdit(QLineEdit):
    ac = pyqtSignal(list)
    def __init__(self, parent=None):
        super(FocusLineEdit, self).__init__(parent)
        self.ac.connect(self.addCompleter)

    def focusInEvent(self, event):
        rtl = call_history(self.objectName())
        self.ac.emit(rtl)

    def addCompleter(self, rtl):
        self.autoCompleter = QCompleter(rtl)
        self.autoCompleter.setCompletionMode(1)
        self.setCompleter(self.autoCompleter)

    def focusOutEvent(self, event):
        pass

Answer 1

It is difficult to analyze where the problem is without you provide an MCVE, so my response implements what you require without taking into account your current code for it must meet the following requirements:

• You must have 2 tables: objects and history that are related.
• The table objects saves the name of the filtering history, it is similar to the use of the objectName that you use, but in general 2 widgets can access the same history if the connection establishes the same name
• In the history table the information of the words associated with the id of the objects table is saved.

In my example I use the following instructions to create them:

CREATE TABLE IF NOT EXISTS objects (id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL UNIQUE);
CREATE TABLE IF NOT EXISTS history (id INTEGER PRIMARY KEY AUTOINCREMENT, id_object INTEGER REFERENCES objects (id), word TEXT NOT NULL, UNIQUE (id_object, word));

Also to test it I created a data, if you already have data then you must eliminate the if test: and everything inside.

Finally for a better understanding of my solution I show a QTableView that is changing according to the selection.

from PyQt5 import QtCore, QtGui, QtWidgets, QtSql

def createConnection():
    db = QtSql.QSqlDatabase.addDatabase('QSQLITE')
    db_path = 'test.db'
    db.setDatabaseName(db_path)
    if not db.open():
        QMessageBox.critical(None, qApp.tr("Cannot open database"),
                             qApp.tr("Unable to establish a database connection.\n"
                                     "This example needs SQLite support. Please read "
                                     "the Qt SQL driver documentation for information "
                                     "how to build it.\n\n"
                                     "Click Cancel to exit."),
                             QMessageBox.Cancel)
        return False

    test = True
    if test:
        query = QtSql.QSqlQuery()
        if not query.exec_('CREATE TABLE IF NOT EXISTS objects (id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL UNIQUE);'):
            return False
        if not query.exec_('CREATE TABLE IF NOT EXISTS history (id INTEGER PRIMARY KEY AUTOINCREMENT, id_object INTEGER REFERENCES objects (id), word TEXT NOT NULL, UNIQUE (id_object, word));'):
            return False

        for i in range(3):
            query.prepare('INSERT INTO objects (name) VALUES (?)')
            query.addBindValue("obj{}".format(i))
            if not query.exec_():
                print(query.lastError().text())
        import requests
        import random
        word_site = "http://svnweb.freebsd.org/csrg/share/dict/words?view=co&content-type=text/plain"
        response = requests.get(word_site)
        WORDS = response.content.decode().splitlines()
        print(WORDS)
        for i in range(3):
            for text in random.sample(WORDS, 50):
                query.prepare('INSERT INTO history (id_object, word) VALUES (?, ?)')
                query.addBindValue(i+1)
                query.addBindValue(text)
                if not query.exec_():
                    print(query.lastError().text())
    return True

class Completer(QtWidgets.QCompleter):
    def __init__(self, parent=None):
        super(Completer, self).__init__(parent)
        self._last_words = []

    def splitPath(self, path):
        if path[-1] != ' ':
            words = path.split()
            self._last_words = words[:-1] if len(words) > 1 else []
            return [words[-1]]
        else:
            QtCore.QTimer.singleShot(0, self.popup().hide)
            return []

    def pathFromIndex(self, index):
        val = super(Completer, self).pathFromIndex(index)
        return ' '.join(self._last_words + [val])

class HistoryManager(QtCore.QObject):
    nameChanged = QtCore.pyqtSignal(str)

    def __init__(self, parent=None):
        super(HistoryManager, self).__init__(parent)
        model = QtSql.QSqlRelationalTableModel(self)
        model.setTable("history")
        model.setRelation(1, QtSql.QSqlRelation("objects", "id", "name"))
        model.select()

        self._proxy = QtCore.QSortFilterProxyModel(self)
        self._proxy.setSourceModel(model)
        self._proxy.setFilterKeyColumn(1)
        # proxy.setFilterFixedString("obj1")

        self._widgets = {}
        self._completer = Completer(self)
        self._completer.setModel(self._proxy)
        self._completer.setCompletionColumn(2)

    def register_widget(self, widget, objectname):
        # TODO
        if callable(getattr(widget, "setCompleter")):
            widget.installEventFilter(self)
            self._widgets[widget] = objectname
            return True
        return False

    def eventFilter(self, obj, event):
        if obj in self._widgets:
            if event.type() == QtCore.QEvent.FocusIn:
                name = self._widgets[obj]
                self._proxy.setFilterFixedString(name)
                obj.setCompleter(self._completer)
                self.nameChanged.emit(name)
            elif event.type() == QtCore.QEvent.FocusOut:
                obj.setCompleter(None)
                self._proxy.setFilterFixedString("")
                self.nameChanged.emit("")
        return super(HistoryManager, self).eventFilter(obj, event)

class Widget(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Widget, self).__init__(parent)
        self._manager = HistoryManager()

        model = QtSql.QSqlRelationalTableModel(self)
        model.setTable("history")
        model.setRelation(1, QtSql.QSqlRelation("objects", "id", "name"))
        model.select()

        self._proxy = QtCore.QSortFilterProxyModel(self)
        self._proxy.setSourceModel(model)
        self._proxy.setFilterKeyColumn(1)

        tv = QtWidgets.QTableView()
        tv.setModel(self._proxy)

        vlay = QtWidgets.QVBoxLayout()
        for i in range(3):
            le = QtWidgets.QLineEdit()
            vlay.addWidget(le)
            self._manager.register_widget(le, "obj{}".format(i))
        vlay.addStretch()
        lay = QtWidgets.QHBoxLayout(self)
        lay.addWidget(tv, stretch=1)
        lay.addLayout(vlay)

        self._manager.nameChanged.connect(self._proxy.setFilterFixedString)

if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    if not createConnection():
        sys.exit(-1)
    manager = HistoryManager()
    w = Widget()
    w.resize(640, 480)
    w.show()
    sys.exit(app.exec_())