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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