QProcess with GUI not freezing

Question

I would like to launch mysql from GUI using QProcess. I've tried the following:

QStringList arguments;
arguments << QString("-u%1").arg("myaccount")<<  QString("-p%2").arg("password");

QProcess *mysql = new QProcess;
mysql->setReadChannelMode(QProcess::ForwardedChannels);
mysql->execute("mysql", arguments);

if(mysql->waitForReadyRead(-1))
    qDebug(mysql->readAllStandardOutput());

But, there is big problem as it's mentioned in Qt Documentation, it's gonna freeze. How can I solve this? Many advised to use QThread but I don't have any idea how to do that? Thanks beforehand!

vahancho · Accepted Answer · 2013-12-08T15:13:16.327

1

The problem is that you call the QProcess::execute() function and it waits until the process is finished. If you need to avoid freezing you can use readyReadStandardOutput() signal and do the following:

[..]
connect(mysql, SIGNAL(readyReadStandardOutput()), this, SLOT(readOutput()));
mysql->start("mysql", arguments);
if (!mysql->waitForStarted()) {
    // report error
}

edited Dec 08 '13 at 15:13

answered Dec 08 '13 at 15:05

vahancho

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Well, Thank you! Also, how can I prompt warning message box when mysql password or user account entered wrong. After connecting readyReadStandardOutput() signal it's gonna be problematic for me to detect this issue. Can you help? – elgolondrino Dec 08 '13 at 15:49
@elgolondrino, I think that depends on how `mysql` reports about incorrect username/password input: exits with error code, prints out error message to standard output or standard error? – vahancho Dec 08 '13 at 19:17

score 0 · Answer 2 · edited May 23 '17 at 11:59

0

This link may help you: QProcess fails to execute external executable

Calling MySQL : c:\mysql\mysql.exe -u MYUSERNAME -pMYPassword

There is no space between -p and password. Set MySQL Path.

edited May 23 '17 at 11:59

Community

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answered Dec 08 '13 at 15:11

Jessica

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QProcess with GUI not freezing

2 Answers2