Get the updater to display a no update found message.

gui/MainWindow.cpp

@@ -681,7 +681,10 @@ void MainWindow::on_actionConfig_Folder_triggered()
 void MainWindow::on_actionCheckUpdate_triggered()
 {
 	auto updater = MMC->updateChecker();
-	updater->checkForUpdate();
+	connect(updater.get(), &UpdateChecker::noUpdateFound, [this](){
+		CustomMessageBox::selectable(this, "No update found.", "No MultiMC update was found!\nYou are using the latest version.")->exec();
+	});
+	updater->checkForUpdate(true);
 }
 
 void MainWindow::on_actionSettings_triggered()

logic/updater/UpdateChecker.cpp

@@ -47,14 +47,16 @@ bool UpdateChecker::hasChannels() const
 	return !m_channels.isEmpty();
 }
 
-void UpdateChecker::checkForUpdate()
+void UpdateChecker::checkForUpdate(bool notifyNoUpdate)
 {
 	QLOG_DEBUG() << "Checking for updates.";
 
-	// If the channel list hasn't loaded yet, load it and defer checking for updates until later.
+	// If the channel list hasn't loaded yet, load it and defer checking for updates until
+	// later.
 	if (!m_chanListLoaded)
 	{
-		QLOG_DEBUG() << "Channel list isn't loaded yet. Loading channel list and deferring update check.";
+		QLOG_DEBUG() << "Channel list isn't loaded yet. Loading channel list and deferring "
+						"update check.";
 		m_checkUpdateWaiting = true;
 		updateChanList();
 		return;
@@ -72,7 +74,8 @@ void UpdateChecker::checkForUpdate()
 	// TODO: Allow user to select channels. For now, we'll just use the current channel.
 	QString updateChannel = m_currentChannel;
 
-	// Find the desired channel within the channel list and get its repo URL. If if cannot be found, error.
+	// Find the desired channel within the channel list and get its repo URL. If if cannot be
+	// found, error.
 	m_repoUrl = "";
 	for (ChannelListEntry entry : m_channels)
 	{
@@ -91,20 +94,22 @@ void UpdateChecker::checkForUpdate()
 
 	auto job = new NetJob("GoUpdate Repository Index");
 	job->addNetAction(ByteArrayDownload::make(indexUrl));
-	connect(job, SIGNAL(succeeded()), SLOT(updateCheckFinished()));
+	connect(job, &NetJob::succeeded, [this, notifyNoUpdate]()
+	{ updateCheckFinished(notifyNoUpdate); });
 	connect(job, SIGNAL(failed()), SLOT(updateCheckFailed()));
 	indexJob.reset(job);
 	job->start();
 }
 
-void UpdateChecker::updateCheckFinished()
+void UpdateChecker::updateCheckFinished(bool notifyNoUpdate)
 {
 	QLOG_DEBUG() << "Finished downloading repo index. Checking for new versions.";
 
 	QJsonParseError jsonError;
 	QByteArray data;
 	{
-		ByteArrayDownloadPtr dl = std::dynamic_pointer_cast<ByteArrayDownload>(indexJob->first());
+		ByteArrayDownloadPtr dl =
+			std::dynamic_pointer_cast<ByteArrayDownload>(indexJob->first());
 		data = dl->m_data;
 		indexJob.reset();
 	}
@@ -112,7 +117,8 @@ void UpdateChecker::updateCheckFinished()
 	QJsonDocument jsonDoc = QJsonDocument::fromJson(data, &jsonError);
 	if (jsonError.error != QJsonParseError::NoError || !jsonDoc.isObject())
 	{
-		QLOG_ERROR() << "Failed to parse GoUpdate repository index. JSON error" << jsonError.errorString() << "at offset" << jsonError.offset;
+		QLOG_ERROR() << "Failed to parse GoUpdate repository index. JSON error"
+					 << jsonError.errorString() << "at offset" << jsonError.offset;
 		return;
 	}
 
@@ -122,7 +128,8 @@ void UpdateChecker::updateCheckFinished()
 	int apiVersion = object.value("ApiVersion").toVariant().toInt(&success);
 	if (apiVersion != API_VERSION || !success)
 	{
-		QLOG_ERROR() << "Failed to check for updates. API version mismatch. We're using" << API_VERSION << "server has" << apiVersion;
+		QLOG_ERROR() << "Failed to check for updates. API version mismatch. We're using"
+					 << API_VERSION << "server has" << apiVersion;
 		return;
 	}
 
@@ -132,19 +139,27 @@ void UpdateChecker::updateCheckFinished()
 	for (QJsonValue versionVal : versions)
 	{
 		QJsonObject version = versionVal.toObject();
-		if (newestVersion.value("Id").toVariant().toInt() < version.value("Id").toVariant().toInt())
+		if (newestVersion.value("Id").toVariant().toInt() <
+			version.value("Id").toVariant().toInt())
 		{
-			QLOG_DEBUG() << "Found newer version with ID" << version.value("Id").toVariant().toInt();
+			QLOG_DEBUG() << "Found newer version with ID"
+						 << version.value("Id").toVariant().toInt();
 			newestVersion = version;
 		}
 	}
 
-	// We've got the version with the greatest ID number. Now compare it to our current build number and update if they're different.
+	// We've got the version with the greatest ID number. Now compare it to our current build
+	// number and update if they're different.
 	int newBuildNumber = newestVersion.value("Id").toVariant().toInt();
 	if (newBuildNumber != MMC->version().build)
 	{
 		// Update!
-		emit updateAvailable(m_repoUrl, newestVersion.value("Name").toVariant().toString(), newBuildNumber);
+		emit updateAvailable(m_repoUrl, newestVersion.value("Name").toVariant().toString(),
+							 newBuildNumber);
+	}
+	else if (notifyNoUpdate)
+	{
+		emit noUpdateFound();
 	}
 
 	m_updateChecking = false;
@@ -163,12 +178,13 @@ void UpdateChecker::updateChanList()
 	if (m_channelListUrl.isEmpty())
 	{
 		QLOG_ERROR() << "Failed to update channel list. No channel list URL set."
-					 << "If you'd like to use MultiMC's update system, please pass the channel list URL to CMake at compile time.";
+					 << "If you'd like to use MultiMC's update system, please pass the channel "
+						"list URL to CMake at compile time.";
 		return;
 	}
 
 	m_chanListLoading = true;
-	NetJob* job = new NetJob("Update System Channel List");
+	NetJob *job = new NetJob("Update System Channel List");
 	job->addNetAction(ByteArrayDownload::make(QUrl(m_channelListUrl)));
 	QObject::connect(job, &NetJob::succeeded, this, &UpdateChecker::chanListDownloadFinished);
 	QObject::connect(job, &NetJob::failed, this, &UpdateChecker::chanListDownloadFailed);
@@ -180,7 +196,8 @@ void UpdateChecker::chanListDownloadFinished()
 {
 	QByteArray data;
 	{
-		ByteArrayDownloadPtr dl = std::dynamic_pointer_cast<ByteArrayDownload>(chanListJob->first());
+		ByteArrayDownloadPtr dl =
+			std::dynamic_pointer_cast<ByteArrayDownload>(chanListJob->first());
 		data = dl->m_data;
 		chanListJob.reset();
 	}
@@ -190,17 +207,20 @@ void UpdateChecker::chanListDownloadFinished()
 	if (jsonError.error != QJsonParseError::NoError)
 	{
 		// TODO: Report errors to the user.
-		QLOG_ERROR() << "Failed to parse channel list JSON:" << jsonError.errorString() << "at" << jsonError.offset;
+		QLOG_ERROR() << "Failed to parse channel list JSON:" << jsonError.errorString() << "at"
+					 << jsonError.offset;
 		return;
 	}
-	
+
 	QJsonObject object = jsonDoc.object();
 
 	bool success = false;
 	int formatVersion = object.value("format_version").toVariant().toInt(&success);
 	if (formatVersion != CHANLIST_FORMAT || !success)
 	{
-		QLOG_ERROR() << "Failed to check for updates. Channel list format version mismatch. We're using" << CHANLIST_FORMAT << "server has" << formatVersion;
+		QLOG_ERROR()
+			<< "Failed to check for updates. Channel list format version mismatch. We're using"
+			<< CHANLIST_FORMAT << "server has" << formatVersion;
 		return;
 	}
 
@@ -210,12 +230,10 @@ void UpdateChecker::chanListDownloadFinished()
 	for (QJsonValue chanVal : channelArray)
 	{
 		QJsonObject channelObj = chanVal.toObject();
-		ChannelListEntry entry{
+		ChannelListEntry entry{channelObj.value("id").toVariant().toString(),
-				channelObj.value("id").toVariant().toString(),
+							   channelObj.value("name").toVariant().toString(),
-				channelObj.value("name").toVariant().toString(),
+							   channelObj.value("description").toVariant().toString(),
-				channelObj.value("description").toVariant().toString(),
+							   channelObj.value("url").toVariant().toString()};
-				channelObj.value("url").toVariant().toString()
-			};
 		if (entry.id.isEmpty() || entry.name.isEmpty() || entry.url.isEmpty())
 		{
 			QLOG_ERROR() << "Channel list entry with empty ID, name, or URL. Skipping.";
@@ -233,7 +251,7 @@ void UpdateChecker::chanListDownloadFinished()
 
 	// If we're waiting to check for updates, do that now.
 	if (m_checkUpdateWaiting)
-		checkForUpdate();
+		checkForUpdate(false);
 
 	emit channelListLoaded();
 }
@@ -244,4 +262,3 @@ void UpdateChecker::chanListDownloadFailed()
 	QLOG_ERROR() << "Failed to download channel list.";
 	emit channelListLoaded();
 }
-

logic/updater/UpdateChecker.h

@@ -25,7 +25,7 @@ class UpdateChecker : public QObject
 
 public:
 	UpdateChecker();
-	void checkForUpdate();
+	void checkForUpdate(bool notifyNoUpdate);
 
 	void setCurrentChannel(const QString &channel) { m_currentChannel = channel; }
 	void setChannelListUrl(const QString &url) { m_channelListUrl = url; }
@@ -65,8 +65,10 @@ signals:
 	//! Signal emitted when the channel list finishes loading or fails to load.
 	void channelListLoaded();
 
+	void noUpdateFound();
+
 private slots:
-	void updateCheckFinished();
+	void updateCheckFinished(bool notifyNoUpdate);
 	void updateCheckFailed();
 
 	void chanListDownloadFinished();

tests/tst_UpdateChecker.cpp

@@ -149,7 +149,7 @@ slots:
 
 		checker.m_channels[0].url = QUrl::fromLocalFile(QDir::current().absoluteFilePath("tests/data/")).toString();
 
-		checker.checkForUpdate();
+		checker.checkForUpdate(false);
 
 		QVERIFY(updateAvailableSpy.wait());
 		QList<QVariant> res = result;