ENUM value from QString

[Dong]

Hi Everyone

I have a lot of custom class with enum define like this:

class BillingEvents : public QObject
{
    Q_OBJECT
    Q_ENUMS(EnumBillingEvents)

public:
    explicit BillingEvents(QObject *parent = 0);

    enum EnumBillingEvents
    {
        APP_INSTALLS,
        CLICKS,
        IMPRESSIONS,
        LINK_CLICKS,
        MULTI_PREMIUM,
        OFFER_CLAIMS,
        PAGE_LIKES,
        POST_ENGAGEMENT,
        VIDEO_VIEWS
    };
};

Q_DECLARE_METATYPE(BillingEvents*);

What I wan't is convert QString something like "APP_INSTALLS", "LINK_CLICK" to Enum Value.

I'm tried this but it doesn't work

        const char *chr = "BillingEvents";
        int type = QMetaType::type(chr);

        const QMetaObject* metaObj = QMetaType::metaObjectForType(type);
        int index = metaObj->indexOfEnumerator("EnumBillingEvents");
        QMetaEnum metaEnum = metaObj->enumerator(index);

        const char* key = "LINK_CLICKS";
        int enumVal = metaEnum.keyToValue(key);
        val = QVariant::fromValue(enumVal);

First Question: Why I cannot register type? I have to add * after Class Name to pass this Error

Q_DECLARE_METATYPE(BillingEvents);
//error: 'QObject::QObject(const QObject&)' is private
//Q_DISABLE_COPY(QObject)

Second Question: How can I get type id (int) from type name? The following code doesn't work.

        const char *chr = "BillingEvents";
        int type = QMetaType::type(chr);

[kshegunov]

@Dong
Hello,

What I wan't is convert QString something like "APP_INSTALLS", "LINK_CLICK" to Enum Value.

If you're using QObject, as you do, you can use QMetaObject::enumerator and the QMetaEnum class.

Q_ENUMS(EnumBillingEvents) this seems wrong, try the Q_ENUM macro

First Question: Why I cannot register type?

Because to declare something as meta-type you need to have a default constructor and a public copy constructor, QObject doesn't allow for copying, so you can't declare it as a metatype. The pointer to QObject however, being an integral type, has all the said characteristics.

Second Question: How can I get type id (int) from type name? The following code doesn't work.

QMetaType::type requires a runtime registration of the class/type, so have you registered it with qRegisterMetaType?

Kind regards.

[Dong]

Thanks for your quick answer.

qRegisterMetaType really does the job.

The only change i made is calling to

qRegisterMetaType<BillingEvents*>("BillingEvents");

before

const char *chr = "BillingEvents";
type = QMetaType::type(chr);

Everything work fined

[kshegunov]

@Dong

Shouldn't this:

qRegisterMetaType<BillingEvents*>("BillingEvents");

be:

qRegisterMetaType<BillingEvents>();

I would think it should.

[Lineaxe]

Hi ,
not sure if this fits your situation.
convert QString something like "APP_INSTALLS", "LINK_CLICK" to Enum Value.
Maybe a hash table would work better than an enum for you, depending on how you are using you EnumBillingEvents that is.

[Dong]

@Lineaxe :
I'm writing a Service Client for Facebook Ads API.
The Response return as JSON data and I have to convert it to Object.
I also have to communicate with other API(s) like Google, Bing, LinkedIn, ...
A Hash table could make confusion between them.
That why I need to convert QString to specific Enum Value.

[Dong]

@kshegunov
I don't know why... but

qRegisterMetaType<BillingEvents>();

Cause Compile Error
error: invalid application of 'sizeof' to incomplete type 'QStaticAssertFailure<false>'
enum {Q_STATIC_ASSERT_PRIVATE_JOIN(q_static_assert_result, __COUNTER __) = sizeof(QStaticAssertFailure<!!(Condition)>)}

[kshegunov]

@Dong
My bad. BillingEvents is actually a QObject and I was thinking about the EnumBillingEvents, so calling qRegisterMetaType<BillingEvents*>(); is perfectly fine (without the string argument).

Kind regards.

[Dong]

@kshegunov
My Enum is defined in a namespace
Without the argument I can't get type by Name

I had to get it with Namespace & * as well.

type = QMetaType::type(qPrintable(QString("FacebookEnums::%1*").arg(propInfo.EnumType)));

It seem a little more complicate... but sometime it had to be.

Thanks a lots !!!