Error in connecting Signals and slots qt6 lineEdit

[yegender]

Hi everyone,

I don't know why this code

QObject::connect(Search, SIGNAL(&QLineEdit::textChanged),
            this,SLOT(&YoutubeTopBar::ChangeSearchStyleSheet));

says that error: No matching member function for call to 'connect'

Thank you

[jsulm]

@yegender Because it's wrong.
If you really want to use the old connect syntax then do it properly:

QObject::connect(Search, SIGNAL(textChanged(const QString)),
                 this,SLOT(ChangeSearchStyleSheet(const QString)));

Better to use "new" Qt5 connect syntax.

[yegender]

None of new and old are working, I tried it with the code you sent same error

[mranger90]

@yegender said in Error in connecting Signals and slots qt6 lineEdit:

QObject::connect(Search, SIGNAL(&QLineEdit::textChanged),
this,SLOT(&YoutubeTopBar::ChangeSearchStyleSheet));

Just use the "new" syntax:
QObject::connect(Search, &QLineEdit::textChanged,
this, &YoutubeTopBar::ChangeSearchStyleSheet);

Assuming that "Search" is a pointer-to-QLineEdit

[jsulm]

@yegender said in Error in connecting Signals and slots qt6 lineEdit:

None of new and old are working

Show the code.
And please show us also YoutubeTopBar definition else nobody know what you have there...

[yegender]

Here is the code:

Header:

#ifndef YOUTUBETOPBAR_H
#define YOUTUBETOPBAR_H

#include <QWidget>
#include <QVBoxLayout>
#include <QHBoxLayout>
#include <QLabel>
#include <QLineEdit>
#include <QToolButton>
#include <QObject>
class YoutubeTopBar : public QWidget
{
    Q_OBJECT
public:
    explicit YoutubeTopBar(QWidget *parent = nullptr);
    QHBoxLayout mainLayout;
    QToolButton ToogleLeftPane;
    QToolButton YoutubeHome;
    QToolButton ToogleDownloadManager;
    QToolButton ToogleSettings;
    QLineEdit Search;


public slots:
    void ChangeSearchStyleSheet();
signals:

};

#endif // YOUTUBELEFTPANE_H

Source File:

#include "youtubetopbar.h"

YoutubeTopBar::YoutubeTopBar(QWidget *parent)
    : QWidget{parent}
{
    this->setWindowTitle("YT Top Bar");
    this->setLayout(&mainLayout);
    mainLayout.setMargin(0);
    mainLayout.setSpacing(0);

    mainLayout.addWidget(&ToogleLeftPane);
    mainLayout.addWidget(&YoutubeHome);
    mainLayout.addWidget(&Search);
    mainLayout.addWidget(&ToogleDownloadManager);
    mainLayout.addWidget(&ToogleSettings);

    ToogleLeftPane.setText("Toogle Left Pane");
    ToogleLeftPane.setStyleSheet("QToolButton{"
                                 "background-color:rgba(0,0,0,0.6);"
                                 "color:white;"
                                 "border:none;"
                                 "margin:5px;"
                                 "padding:10px;"
                                 "}"
                                 "QToolButton::hover{"
                                 "background-color:rgba(255,255,255,0.1);"
                                 "border-radius:5px;"
                                 "}");
    YoutubeHome.setText("Youtube");
    YoutubeHome.setStyleSheet("QToolButton{"
                              "background-color:rgba(0,0,0,0.6);"
                              "color:white;"
                              "border:none;"
                              "margin:5px;"
                              "padding:10px;"
                              "}"
                              "QToolButton::hover{"
                              "background-color:rgba(255,255,255,0.1);"
                              "border-radius:5px;"
                              "}");
    ToogleSettings.setText("Settings");
    ToogleSettings.setStyleSheet("QToolButton{"
                                 "background-color:rgba(0,0,0,0.6);"
                                 "color:white;"
                                 "border:none;"
                                 "margin:5px;"
                                 "padding:10px;"
                                 "}"
                                 "QToolButton::hover{"
                                 "background-color:rgba(255,255,255,0.1);"
                                 "border-radius:5px;"
                                 "}");
    ToogleDownloadManager.setText("Download Manager");
    ToogleDownloadManager.setStyleSheet("QToolButton{"
                                        "background-color:rgba(0,0,0,0.6);"
                                        "color:white;"
                                        "border:none;"
                                        "margin:5px;"
                                        "padding:10px;"
                                        "}"
                                        "QToolButton::hover{"
                                        "background-color:rgba(255,255,255,0.1);"
                                        "border-radius:5px;"
                                        "}");
    Search.setPlaceholderText("Search");
    Search.setStyleSheet("QLineEdit{"
                         "background-color:rgba(0,0,0,0.3);"
                         "border:none;"
                         "margin:5px;"
                         "padding:10px;"
                         "border-radius:5px;"
                         "}"
                         "QLineEdit::hover{"
                         "background-color:rgba(255,255,255,0.1);"
                         "border-radius:5px;"
                         "}");

    QObject::connect(Search, &QLineEdit::textChanged),this,&YoutubeTopBar::ChangeSearchStyleSheet);
}

void YoutubeTopBar::ChangeSearchStyleSheet(){
    if(Search.text().isEmpty()){
        Search.setStyleSheet("color:rgba(255,255,255,0.6);");
    } else {
        Search.setStyleSheet("color:white;");
    }
}

CMAKE:

cmake_minimum_required(VERSION 3.5)

project(video-player VERSION 0.1 LANGUAGES CXX)

set(CMAKE_INCLUDE_CURRENT_DIR ON)

set(CMAKE_AUTOUIC ON)
set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTORCC ON)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

find_package(QT NAMES Qt6 Qt5 REQUIRED COMPONENTS Widgets)
find_package(Qt${QT_VERSION_MAJOR} REQUIRED COMPONENTS Widgets)

set(PROJECT_SOURCES
        main.cpp
        mainwindow.cpp mainwindow.h
        youtubeleftpane.h youtubeleftpane.cpp
        youtubetopbar.h youtubetopbar.cpp
        youtubebanner.h youtubebanner.cpp
        youtubepage.h youtubepage.cpp
        youtubetopbarwrapper.h youtubetopbarwrapper.cpp
)

if(${QT_VERSION_MAJOR} GREATER_EQUAL 6)
    qt_add_executable(video-player
        MANUAL_FINALIZATION
        ${PROJECT_SOURCES}
    )
# Define target properties for Android with Qt 6 as:
#    set_property(TARGET video-player APPEND PROPERTY QT_ANDROID_PACKAGE_SOURCE_DIR
#                 ${CMAKE_CURRENT_SOURCE_DIR}/android)
# For more information, see https://doc.qt.io/qt-6/qt-add-executable.html#target-creation
else()
    if(ANDROID)
        add_library(video-player SHARED
            ${PROJECT_SOURCES}
        )
# Define properties for Android with Qt 5 after find_package() calls as:
#    set(ANDROID_PACKAGE_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/android")
    else()
        add_executable(video-player
            ${PROJECT_SOURCES}
        )
    endif()
endif()

target_link_libraries(video-player PRIVATE Qt${QT_VERSION_MAJOR}::Widgets)

set_target_properties(video-player PROPERTIES
    MACOSX_BUNDLE_GUI_IDENTIFIER my.example.com
    MACOSX_BUNDLE_BUNDLE_VERSION ${PROJECT_VERSION}
    MACOSX_BUNDLE_SHORT_VERSION_STRING ${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}
    MACOSX_BUNDLE TRUE
    WIN32_EXECUTABLE TRUE
)

if(QT_VERSION_MAJOR EQUAL 6)
    qt_finalize_executable(video-player)
endif()

And I am using this class widget inside a layout of another widget

Thank you

[JonB]

@yegender said in Error in connecting Signals and slots qt6 lineEdit:

QObject::connect(Search, &QLineEdit::textChanged),this,&YoutubeTopBar::ChangeSearchStyleSheet);

Please just count your parentheses or copy/paste what was suggested to you, nobody wrote the above. Hence the error message.

[Christian Ehrlicher]

@yegender said in Error in connecting Signals and slots qt6 lineEdit:

QObject::connect(Search, &QLineEdit::textChanged),this,&YoutubeTopBar::ChangeSearchStyleSheet);

This does not even compile...

Also please create objects on the heap instead adding them as objects in your class - it will most likely crash when the YoutubeTopBar object gets destroyed since then the children are beeing deleted automatically which will not work in your case - see QObject Trees and Ownership.

[yegender]

@JonB Same error

[Christian Ehrlicher]

@yegender said in Error in connecting Signals and slots qt6 lineEdit:

@JonB Same error

What error? Fix your code and post your real code + compiler error.

[JonB]

@yegender
Then you have something else wrong. People cannot help if we do not have the exact line copied and pasted from your live code, together with the text of the error message. All copied for 100% certain.

[yegender]

This is the exact Line I have copied

[Christian Ehrlicher]

Because Search is an object, not a pointer - pass a pointer because QObject::connect() wants pointers.

[yegender]

Thank you, now I got why actually mostly pointers are used.