I followed the database creation app on http://developer.blackberry.com/native/sampleapps/ but I can't figure out how can I create the database/retrieve data when my app loads. Can someone help me with good reference books for using sqlite3 with cascades, I can't find any good source for it.
There are a few ways, but I used this one so far (it's not perfect but good enough).
First save customsqldatasource.cpp and customsqldatasource.h inside your /src directory.
Open your applicationui.cpp and add to the top
#include "customsqldatasource.h"
and add this inside ApplicationUI to expose it to QML:
qmlRegisterType<CustomSqlDataSource>("com.myapp.data", 1, 0, "CustomSqlDataSource");
Add LIBS += -lbbdata to your .pro file
add your database in /assets; location is up to you, just make sure it matches source in CustomSqlDataSource
add import com.myapp.data 1.0 to your .qml file
Within attachedObjects add this:
CustomSqlDataSource {
id: asynkDataSource
source: "sql/mydatabase.db"
query: "SELECT * FROM recent_searches GROUP BY fromCity, toCity ORDER BY id DESC"
onDataLoaded: {
if (data.length > 0) {
//use data
}
}
}
Now all you need to do is add the following line inside onCreationCompleted to load it
asynkDataSource.load();
I hope I didn't forget anything. A few important things: /assets folder is read only, therefore your .db is copied to /data folder (this script does it).
Related
I use Qt Installer Framework.
I want to know how to prevent installation in a non-empty folder?
In addition, how can I make the uninstaller remove only the files and folders it has installed, and not all the contents of its folder?
Thank you in advance
Due to the Qt Documentation you have access to the QDesktopServices inside the Scripting API, which contains the function findFiles(string path,string pattern), which should return none in your case, where path is your target directory for installation.
In the TargetDirectory Installer Installer Page you have access to the set TargetDirectory via Installer Page, which can be connected to if there is some edit.
It took me some hard time to figure out the following solution, which I have to admit is not the way I wanted to have it beforehand.
First of all you need a control script, that needs to be set inside your config.xml. It is called controlScript.js and resides in the same directory as your config.xml.
config.xml
<?xml version="1.0" encoding="UTF-8"?>
<Installer>
<Name>Your application</Name>
<Version>1.0.0</Version>
<Title>Your application Installer</Title>
<Publisher>Your vendor</Publisher>
<StartMenuDir>Super App</StartMenuDir>
<TargetDir>#HomeDir#/InstallationDirectory</TargetDir>
<ControlScript>controlScript.js</ControlScript>
</Installer>
Now, the only solution that I brought to work is the following:
controlScript.js
function Controller()
{
console.log("Control script");
}
Controller.prototype.ComponentSelectionPageCallback = function() {
var widget = gui.currentPageWidget();
widget.title="Select empty directory!";
var targetDirWidget = gui.pageById(QInstaller.TargetDirectory);
var targetDir=targetDirWidget.TargetDirectoryLineEdit.text;
var files=QDesktopServices.findFiles(targetDir, "*.*");
if (files.length!=0) {
var result = QMessageBox.warning("quit.question", "You selected a non-empty directory!", targetDir,QMessageBox.Ok);
gui.clickButton(buttons.BackButton);
}
}
Basically, the user enters a target directory and presses the BackButton. In case the target directory is non-empty a message box is displayed and the BackButton in the Component Selection is pressed.
My desired solution was beforehand to deactivate the NextButton in the TargetDirectory Page, but all my attempts were futile. Even though the following disabling of the NextButton should work, as shown in this answer.
I am importing 2 QML files that come with Qt Controls - ScrollBar.qml and Button.qml in my project. I pre-compile all .qml files that I wrote to reduce application launch time. Is there a way to pre-compile these 2 QML files that come as part of the package?
I tried to remove these files from the qml/QtQuick/Controls/ path and placed them in the same folder as my .qml files but it still failed to load. When I reference ScrollBar in my code, it always tries to load ScrollBar.qml from qml/QtQuick/Controls/ path.
Does any one know if it is possible to pre-compile these QMLs at all? If yes, has any one successfully done it?
Appreciate any help. Thank you.
I'm assuming that you're referring to the Qt Quick Compiler as pre-compiling. The simplest way would just be to build the entire Qt Quick Controls module with the Qt Quick Compiler.
If you need to have it within your project, you could try adding an import that contains the Qt Quick Controls import. QQmlEngine::addImportPath() says:
The newly added path will be first in the importPathList().
That statement seems to imply that order matters, and the code confirms it:
QStringList localImportPaths = database->importPathList(QQmlImportDatabase::Local);
// Search local import paths for a matching version
const QStringList qmlDirPaths = QQmlImports::completeQmldirPaths(uri, localImportPaths, vmaj, vmin);
for (const QString &qmldirPath : qmlDirPaths) {
QString absoluteFilePath = typeLoader.absoluteFilePath(qmldirPath);
if (!absoluteFilePath.isEmpty()) {
QString url;
const QStringRef absolutePath = absoluteFilePath.leftRef(absoluteFilePath.lastIndexOf(Slash) + 1);
if (absolutePath.at(0) == Colon)
url = QLatin1String("qrc://") + absolutePath.mid(1);
else
url = QUrl::fromLocalFile(absolutePath.toString()).toString();
QQmlImportDatabase::QmldirCache *cache = new QQmlImportDatabase::QmldirCache;
cache->versionMajor = vmaj;
cache->versionMinor = vmin;
cache->qmldirFilePath = absoluteFilePath;
cache->qmldirPathUrl = url;
cache->next = cacheHead;
database->qmldirCache.insert(uri, cache);
*outQmldirFilePath = absoluteFilePath;
*outQmldirPathUrl = url;
return true;
}
}
Your project structure might look something like this:
myproject/
qml/
main.qml
QtQuick/
Controls/
Button.qml
ScrollBar.qml
qmldir
In main.cpp you'd set the path to the qml directory (note that the path will be different depending on whether you're doing an in-source build or a shadow build of your project, so you may want to use a resource file to simplify things):
engine.addImportPath("path/to/qml");
Note that the controls import other types. For example, Button uses the Settings singleton, which comes from the QtQuick.Controls.Private import, so you'd need to copy that into the qml directory, too. Settings loads a certain style for the button (ButtonStyle), which could be any of the styles in this folder, depending on which style is in use.
In short, you need to copy all of the potential dependencies of the QML files you're using.
I'm making an application part of which is reading from an XML which stores some preferences. However, whenever I build the project, all the sources get copied but the preferences file does not! I have added the following to the .pro file -
RESOURCES += rsc.qrc
And my rsc.qrc contains
<!DOCTYPE RCC><RCC version="1.0">
<qresource>
<file>data/preferences.xml</file>
<file>data/gamedata.xml</file>
</qresource>
</RCC>
Now whenever I try to open preferences.xml
QFile preferences(":/data/preferences.xml");
if(!preferences.exists()){
preferences.open(QFile::WriteOnly);
preferences.write("abc");
qDebug() << "Written";
}
else {
qDebug() << "File exists";
}
Absolutely nothing gets printed and even the rest of the application stops working.
You don't use the resource part correctly in your example.
It will most likely not work because you try to write to a resource that is embedded into your executable after you have build your application. Reading is fine, but writing can't work by definition.
If you want a editable setting files, you have to distribute them along with your executable, or use a different method for reading/writing your settings like QSettings.
However using QSettings also means, that you will need to configure all your default settings in your loading function in case the values do not exist if you use the default configuration. Meaning you use registry on windows.
You have the option to force the use of a INI file format in the constructor of QSettings, this can make sense if you want to provide a default settings INI file instead of your xml files.
In case you want to store more complex data a xml file might be needed anyway, so if you want to stick with that you will need a way to copy your setting files to your build path. This can be done within your pro file with QMAKE_POST_LINK.
Example:
COPY_CMD = "$$PWD\\data\\preferences.xml $$OUT_PWD\\release\\data\\preferences.xml"
COPY_CMD = $${QMAKE_COPY} $$replace( COPY_CMD, "/", "\\" ) $$escape_expand( \\n\\t )
QMAKE_POST_LINK += $$COPY_CMD
I am working on Nginx server, with PHP-FPM. I installed Laravel 4.1 and bootstrap v3.1.1., and here is the problem. For the last 30 minutes, I have been trying to change a css rule that I first declared to check boostrap.
.jumbotron{
background: red;
}
The first time it worked. The jumbotron container was red. So, I removed that css value and started working, but still no matter which browse I use, the container is red. I even checked the css file through the Google Chromes inspection tool, and it is showing me that first value when jumbotron had a background:red. I deleted the css file and renamed it and add new styles, I configured chrome not to cache pages. But Still the same value. I'm convinced now, that Laravel has kept a cache of the first style declaration.
Is there any way to disable this at all?
General explanation
When you access a Laravel Blade view, it will generate it to a temporary file so it doesn't have to process the Blade syntax every time you access to a view. These files are stored in app/storage/view with a filename that is the MD5 hash of the file path.
Usually when you change a view, Laravel regenerate these files automatically at the next view access and everything goes on. This is done by comparing the modification times of the generated file and the view's source file through the filemtime() function. Probably in your case there was a problem and the temporary file wasn't regenerated. In this case, you have to delete these files, so they can be regenerated. It doesn't harm anything, because they are autogenerated from your views and can be regenerated anytime. They are only for cache purposes.
Normally, they should be refreshed automatically, but you can delete these files anytime if they get stuck and you have problems like these, but as I said these should be just rare exceptions.
Code break down
All the following codes are from laravel/framerok/src/Illuminate/View/. I added some extra comments to the originals.
Get view
Starting from Engines/CompilerEngine.php we have the main code we need to understand the mechanics.
public function get($path, array $data = array())
{
// Push the path to the stack of the last compiled templates.
$this->lastCompiled[] = $path;
// If this given view has expired, which means it has simply been edited since
// it was last compiled, we will re-compile the views so we can evaluate a
// fresh copy of the view. We'll pass the compiler the path of the view.
if ($this->compiler->isExpired($path))
{
$this->compiler->compile($path);
}
// Return the MD5 hash of the path concatenated
// to the app's view storage folder path.
$compiled = $this->compiler->getCompiledPath($path);
// Once we have the path to the compiled file, we will evaluate the paths with
// typical PHP just like any other templates. We also keep a stack of views
// which have been rendered for right exception messages to be generated.
$results = $this->evaluatePath($compiled, $data);
// Remove last compiled path.
array_pop($this->lastCompiled);
return $results;
}
Check if regeneration required
This will be done in Compilers/Compiler.php. This is an important function. Depending on the result it will be decided whether the view should be recompiled. If this returns false instead of true that can be a reason for views not being regenerated.
public function isExpired($path)
{
$compiled = $this->getCompiledPath($path);
// If the compiled file doesn't exist we will indicate that the view is expired
// so that it can be re-compiled. Else, we will verify the last modification
// of the views is less than the modification times of the compiled views.
if ( ! $this->cachePath || ! $this->files->exists($compiled))
{
return true;
}
$lastModified = $this->files->lastModified($path);
return $lastModified >= $this->files->lastModified($compiled);
}
Regenerate view
If the view is expired it will be regenerated. In Compilers\BladeCompiler.php we see that the compiler will loop through all Blade keywords and finally give back a string that contains the compiled PHP code. Then it will check if the view storage path is set and save the file there with a filename that is the MD5 hash of the view's filename.
public function compile($path)
{
$contents = $this->compileString($this->files->get($path));
if ( ! is_null($this->cachePath))
{
$this->files->put($this->getCompiledPath($path), $contents);
}
}
Evaluate
Finally in Engines/PhpEngine.php the view is evaluated. It imports the data passed to the view with extract() and include the file with the passed path in a try and catch all exceptions with handleViewException() that throws the exception again. There are some output buffering too.
Same issue here. I am using VirtualBox with Shared Folders pointing to my document root.
This pointed me in the right direction:
https://stackoverflow.com/a/26583609/1036602
Which led me to this:
http://www.danhart.co.uk/blog/vagrant-virtualbox-modified-files-not-updating-via-nginx-apache
and this:
https://forums.virtualbox.org/viewtopic.php?f=1&t=24905
If you're mounting your local dev root via vboxsf Shared Folders, set EnableSendFile Off in your apache2.conf (or sendfile off if using Nginx).
For what it's worth and because this answer came up first in my google search...
I had the same problem. The CSS and JS files wouldn't update. Deleting the cache files didn't work. The timestamps were not the problem. The only way I could update them was to change the filename, load it directly to get the 404 error, and then change the name back to the original name.
In the end the problem was not related to Laravel or the browser cache at all. The problem was due to NginX using sendfile which doesn't work with remote file systems. In my case, I was using VirtualBox for the OS and the remote file system was vboxsf through Guest Additions.
I hope this saves someone else some time.
In Laravel 5.8+ you can use so:
The version method will automatically append a unique hash to the filenames of all compiled files, allowing for more convenient cache busting:
mix.js('resources/js/app.js', 'public/js').version();
After generating the versioned file, you won't know the exact file name. So, you should use Laravel's global mix function within your views to load the appropriately hashed asset. The mix function will automatically determine the current name of the hashed file:
<script src="{{ mix('/js/app.js') }}"></script>
full document: https://laravel.com/docs/5.8/mix
I've created an installer package based on the Qt installer framework with multiple components.
I needed to install each component in the appropriate directory.
Is it possible to specify the target directory for the individual component? I am referring to something like this:
var appData = installer.environmentVariable("AppData");
if (appData != "")
component.setValue("TargetDir", appData+ "/MyComponent");
Thank you in advance.
This question has already been answered, but I thought I would add a more detailed answer.
The documentation states that "for each component, you can specify one script that prepares the operations to be performed by the installer."
The Qt installer framework QtIFW comes with a set of examples, one of which is called modifyextract. Using this, I modified my package.xml file to include the line
<Script>installscript.qs</Script>
I then added a file installscript.qs to my package meta directory with the following content
function Component()
{
}
Component.prototype.createOperationsForArchive = function(archive)
{
// don't use the default operation
// component.createOperationsForArchive(archive);
// add an extract operation with a modified path
component.addOperation("Extract", archive, "#TargetDir#/SubDirectoryName");
}
The files in the package data folder were then installed in the subfolder SubDirectoryName
You need this based on the documentation:
Extract "Extract" archive target directory Extracts archive to target directory.
In my case, the component.addOperation("Extract", ... line resulted in extracting to #TargetDir#.
Instead, use one of the 'Operations> options in the Package.xml file.