Use an QObject found by it's QObjectName

Question

I have a little problem in my program. I have a config file put in settings. I pull from it the names of the object I need to be checked (these are QCheckBox). I have this piece of code (It compiles and runs but when it's at "cBox->setChecked" it just crash):

void Preproc::on_tBtnManual_toggled(bool checked){

if(checked){
    ui->tBtnManual->setText("Systematic");
}else{
    ui->tBtnManual->setText("Manual");
    settings.beginGroup("Preprocessing");
    QStringList keys = settings.childKeys();
    foreach(QString configParam,keys){
        QCheckBox *cBox = ui->gridLayout->findChild<QCheckBox *>(configParam);
        cBox->setChecked(settings.value(configParam).toBool());
    }
 }

}

I have tried to put ui->cBox->... put it says that cBox is not a child of ui. If I qDebug(cBox) I have a QObject(0x0) so nothing !

I'm a little new to Qt so maybe it's a simple thing. Thanks and have a nice day :)

score 1 · Answer 1 · answered Jun 07 '13 at 14:11

1

Are you sure that an object is found? I don't think so (different name? wrong layout?). cBox is 0x0 when nothing is found. However put a

if (cBox)

before

cBox->setChecked(settings.value(configParam).toBool());

and it will not crash anymore when it doesn't find an object by name.

answered Jun 07 '13 at 14:11

asclepix

7,971
3
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Yes it didn't crash anymore but I still have a QObject null. I checked the name and they're good. – Pico Jun 07 '13 at 16:28

WoJo · Answer 2 · 2013-06-07T14:25:32.107

0

are you sure the name (content of configParam) is correct? you can try the search from QApplication

QApplication::instance()->findChild<QCheckBox *>(configParam);

the findChild method performs a recursive search, if the object exists in the hirachie, it will be found. if the object is not found, it could be:

the object does not exist
the object has another name
the object or one of its ancestors has no (NULL) parent

can you post the part of the .ui file with the check box? it would be helpful.

edited Jun 07 '13 at 14:25

answered Jun 07 '13 at 14:16

WoJo

360
2
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Here is my settings.ini from where it gets its parameters `[Preprocessing] cBoxGain=true cBoxMask=true` – Pico Jun 07 '13 at 16:29
` false Gain Error true ` I've shortened my code by deleting others QcheckBox. Also I always got the same null object with your code – Pico Jun 07 '13 at 16:31
you searched for "cBox" (ui->cBox->...), but the name is `name="cBoxGain"` try ui->cBoxGain (or `findChild("cBoxGain")` ) – WoJo Jun 09 '13 at 16:03

Use an QObject found by it's QObjectName

2 Answers2