This is a text-only version of the following page on https://raymii.org:
---
Title       : 	Log all Item properties and functions in Qml
Author      : 	Remy van Elst
Date        : 	09-02-2022
URL         : 	https://raymii.org/s/snippets/Log_all_Item_properties_and_functions_in_Qml.html
Format      : 	Markdown/HTML
---





This small snippet of Javascript logs all properties and functions of a Qml Item. This is useful when you're knees-deep in a dynamic control that has a model and you're wondering why your code does not work. Probably because you're not using the correct property name. Or at least, that is something I often have. Logging all properties or functions helps to figure out that issue.

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![demo program][1]

> A demo program that logs functions and properties to the command line and a `TextArea`

The code to log all properties is actually very simple:

    function listProperties(item) {
        var properties = ""
        for (var p in item)
            if (typeof item[p] != "function")
                properties += (p + ": " + item[p] + "\n")
        return properties
    }

Same goes for logging all functions:

    function listFunctions(item) {
        var functions = ""
        for (var f in item)
            if (typeof item[f] == "function")
                functions += (f + ": " + item[f] + "\n")
        return functions
    }


If you remove the `if(typeof...` then you get both in the output. 

Usage is simple, just pass the `id:` of an item you want to log:

    Button {
        id: logButton
        [...]
        text: "Log Properties"
        onClicked: {
            console.log(listProperties(logButton))
        }
    }

You could also use `JSON.stringify()` but I have seen recursive loops that 
crashed when using that, so this is my small goto snippet.    


### Demo Qml Program

Here's a small Qml demo program that logs either functions 
or properties to the command line and a `TextArea`.

**main.qml**

    import QtQuick 2.15
    import QtQuick.Controls 2.12
    import QtQuick.Window 2.15
    
    Window {
        width: 640
        height: 480
        visible: true
        title: qsTr("Log Properties Example")
    
        function listProperties(item) {
            var properties = ""
            for (var p in item)
                if (typeof item[p] != "function")
                    properties += (p + ": " + item[p] + "\n")
            return properties
        }
    
        function listFunctions(item) {
            var functions = ""
            for (var f in item)
                if (typeof item[f] == "function")
                    functions += (f + ": " + item[f] + "\n")
            return functions
        }
    
        Button {
            id: logButton
            anchors.top: parent.top
            anchors.left: parent.left
            anchors.margins: 50
            objectName: "Raymii.org Example"
            text: "Log Properties"
            onClicked: {
                console.log(listProperties(logButton))
                logTextarea.text = listProperties(logButton)
            }
        }
    
        Button {
            id: logFunctionsButton
            anchors.top: parent.top
            anchors.left: logButton.right
            anchors.margins: 50
            text: "Log Functions"
            onClicked: {
                console.log(listFunctions(logFunctionsButton))
                logTextarea.text = listFunctions(logFunctionsButton)
            }
        }
    
        ScrollView {
            id: propertyview
            anchors.top: logButton.bottom
            anchors.left: parent.left
            anchors.margins: 50
            width: 500
            height: 300
    
            TextArea {
                id: logTextarea
                anchors.fill: parent
                placeholderText: "click the buttons"
            }
        }
    }



**main.cpp**

    #include <QGuiApplication>
    #include <QQmlApplicationEngine>
    
    
    int main(int argc, char *argv[])
    {
    #if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
        QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
    #endif
    
        QGuiApplication app(argc, argv);
    
        QQmlApplicationEngine engine;
        const QUrl url(QStringLiteral("qrc:/main.qml"));
        QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,
                         &app, [url](QObject *obj, const QUrl &objUrl) {
            if (!obj && url == objUrl)
                QCoreApplication::exit(-1);
        }, Qt::QueuedConnection);
        engine.load(url);
    
        return app.exec();
    }



[1]: /s/inc/img/qml_log_properties.png

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