[SOLVED] QPluginLoader unable to load a Qt Plugin

[bharath144]

Hello all,

I have an Interface as shown below.

class MyInterface
{
    public:
        virtual ~MyInterface() {}
        virtual int initialize() = 0;
};

Q_DECLARE_INTERFACE(MyInterface, "com.example.MyInterface/1.0")

My plugin implements this interface and declares it in its class as shown below.

class QT_DECL_EXPORT MyPlugin : public QObject, public MyInterface
{
    Q_OBJECT
    Q_INTERFACES(MyInterface)

    public:
        MyPlugin();
        virtual ~MyPlugin();

    public:
        int initialize();

        // ...
};

My plugin's project file sets the target appropriately.

TARGET = $$qtLibraryTarget(MyPlugin)
TEMPLATE = lib

Now, all the modules (including my app) gets compiled. In the app where I have to load the plugin, I have the following code:

// ...

QPluginLoader loader("MyPluginld.dll");
if (! loader.load())
    qDebug() << "Error!";

MyInterface *base = qobject_cast<MyInterface *>(loader.instance());
if (base == NULL)
    qDebug() << "Error!";

// ...

The loader.load() function always fails. Am I making a mistake by providing incorrect name to the QPluginLoader constructor? Or is something else wrong?

Any help would be much appreciated.

Cheers!
Bharath

[mcosta]

In your code you expect that the DLL is in the same directory of the executable.
Is that TRUE??

[bharath144]

@mcosta Yes, that is correct. My deployment model ensures that both land up in the same directory.

Cheers!
ಮೈ ಗೋ ಭರತ ನಾರಾಯಣ
Bharath Narayan M G

[mcosta]

Hi,

if your DLL is in the right place you can use QPluginLoader::errorString()to understand why load fails

[bharath144]

@mcosta Thanks for that. I will see what the error string says.

[bharath144]

@mcosta
The errorString prints the following:

"Plugin verification data mismatch in './/MyPluginld.dll'"

[mcosta]

@bharath144 said:

Plugin verification data mismatch in

Had a quick look to Qt sources.
Seems that you must use this macro to define plugin's metadata.

Reading here, the point 3. of "Writing a plugin involves these steps:" says the same thing

[bharath144]

@mcosta That did the trick. I saw the step but I overlooked it thinking it may not be mandatory.

Thanks for the help.

[LeaA]

hello,

can you tell us how you solve your problem?
thank you.