[Solved] Deserialisation of QVector doesn't work for me

moravas

Hi People,

I have a problem with mentioned topic. I have an custom template class and I would like it serialise and vice versa into an QDataStream. The usage of the stream looks like:
@
QByteArray array;

s s0 = 7;
QDataStream stream(&array, QIODevice::ReadWrite);

stream << s0;
stream.device()->reset();
stream >> s0;

@

and the serialise and deserialise operators:
@
template<R_ARGS_DEF> QDataStream& operator<<(QDataStream& stream, const dimension<R_ARGS>& in) {
stream << in.raw();
QVector<s32> templateArgVector = {R_ARGS};
stream << templateArgVector;
return stream;
}

template<R_ARGS_DEF, typename typeOfValue> QDataStream& operator>>(QDataStream& stream, dimension<R_ARGS, typeOfValue>& out) {
QVector<s32> templateArgVector = {R_ARGS};
QVector<s32> streamArgVector;
stream >> streamArgVector;

if(streamArgVector != templateArgVector) {
    throw new BadDeserialisationTemplateTypeException();
}

typeOfValue tmp;
stream >> tmp;
out = tmp;
return stream;

}
@

you can see that I serialise the raw data(raw() method) and the template arguments via an QVector into the stream, and it works: if I use QFile instead of QByteArray as container for stream, the file will correct.
The error occurred on the deserialising this QVector from the stream. After this operation would I like compare the two vector, but the result is an exception.

I don't know: I make something wrong or it is an bug in the framework?
Have anybody something idea?

Regards,
Norbert

ChrisW67

It seems you stream out two objects:

Whatever type in.raw() is [line 2]
A QVector<s32> containing R_ARGS [line 4]

On the way in your code:

Streams in data that was in in.raw() as if it were a QVector<s32> [line 11]... was it?
Compares that data to what I would expect to see in the QVector<s32>, which you have not streamed in.
Then expects to continue streaming in if the condition was met. I would expect the stream to be exhausted at that point.

We have no idea what type 's', 's32', or 'dimension' is, or what R_ARGS is... which may have helped. Your template does not seem to use the template variable R_ARGS_DEF either.

moravas

Hi ChrisW67,

yes, I would like serialise two object:

the in.raw() gets back an doube value
the R_ARGS is an #define for 14 pieces int types
the R_ARGS_DEF is the definition for the R_ARGS

In my sources marks the s32 an int type (s as signed, 32 as 32 bit).
"s" is an typedef for "dimension" template class, like this:
@
typedef dimension<0,1,0,1,0,1,0,1,0,1,0,1,0,1,> s;
@

Regards,
Norbert

ChrisW67

OK, in.raw() returns a double and your stream that out first, followed by your QVector<s32>. When you stream in you do not read a double from the stream before you attempt to read your QVector<s32>.

moravas

Thank you for help. It works for me :) I closed the post.

Regards,
Norbert