QCompleter doesn't work properly with NetworkRequest finished - c++

Question

Qcompleter which is associated with a lineEdit doesn't work in the slot of a QNetworkRequest finished.The Qcompleter disappeared quite quickly.Each time the text in lineEdit changed a request was send.I tried a demo without other code,it also occured.
Every time the text in lineEdit was edit,a request contains the text will be send to my server.And then I want to show the content in reply in a Qcompleter.But the prompt disappears in a instant.
void MainWindow::onRequestFinished(QNetworkReply* reply){
QStringList stringList;
stringList << "test1" <<"test2"<<"test3";
QCompleter* completer = new QCompleter(stringList,this);
completer->setCompletionMode(QCompleter::UnfilteredPopupCompletion);
ui->lineEdit->setCompleter(completer);
reply->deleteLater();
}
void MainWindow::on_lineEdit_textChanged(const QString &arg1)
{
QUrl url("http://www.google.com");
QNetworkRequest request;
request.setUrl(url);
manager->get(request);
}
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow){
...
this->manager = new QNetworkAccessManager(this);
connect(manager,SIGNAL(finished(QNetworkReply*)),this,SLOT(onRequestFinished(QNetworkReply*)));
...
}

Answer 1

The logic is similar to an old answer of mine, in it a model is created that will store the information this prevents you from creating a QCompleter at every moment avoiding the problem the disappearance of the popup.
#include <QtWidgets>
#include <QtNetwork>
class SuggestModel: public QStandardItemModel
{
Q_OBJECT
public:
using QStandardItemModel::QStandardItemModel;
void search(const QString & text)
{
QNetworkRequest request = create_request(text);
if(m_reply)
m_reply->abort();
m_reply = manager.get(request);
connect(m_reply, &QNetworkReply::finished, this, &SuggestModel::onFinished);
QEventLoop loop;
connect(this, &SuggestModel::finished, &loop, &QEventLoop::quit);
loop.exec();
}
private Q_SLOTS:
void onFinished(){
QNetworkReply *reply = qobject_cast<QNetworkReply *>(sender());
QUrl url = reply->url();
if (reply->error() == QNetworkReply::NoError) {
QVector<QString> choices;
QByteArray response(reply->readAll());
QXmlStreamReader xml(response);
while (!xml.atEnd()) {
xml.readNext();
if (xml.tokenType() == QXmlStreamReader::StartElement)
if (xml.name() == "suggestion") {
QStringRef str = xml.attributes().value("data");
choices << str.toString();
}
}
clear();
for(const QString & choice: choices)
appendRow(new QStandardItem(choice));
}
reply->deleteLater();
Q_EMIT finished();
m_reply = nullptr;
}
Q_SIGNALS:
void finished();
private:
QNetworkRequest create_request(const QString & text){
const QString suggestUrl(QStringLiteral("http://google.com/complete/search?output=toolbar&q=%1"));
QString url = suggestUrl.arg(text);
return QNetworkRequest(url);
}
QNetworkAccessManager manager;
QNetworkReply *m_reply = nullptr;
};
class SuggestCompleter: public QCompleter{
public:
SuggestCompleter(QObject *parent=nullptr):
QCompleter(parent)
{
SuggestModel *m_model = new SuggestModel(this);
setModel(m_model);
setCompletionMode(QCompleter::UnfilteredPopupCompletion);
}
QStringList splitPath(const QString &path) const override{
if(SuggestModel * m = qobject_cast<SuggestModel *>(model()))
m->search(path);
return QCompleter::splitPath(path);
}
};
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QLineEdit le;
le.setCompleter(new SuggestCompleter(&le));
le.show();
return a.exec();
}
#include "main.moc"