Can you add a custom object to a SQL database?

[agerlach]

I have the following class:

class siStore
{
public:
siStore();
~siStore();

QVector<float> *si;
float siSum;
float si2Sum;
int length;
int siWidth;
}

In my program I then create a QList<siStore*> called siStack.

In practice, the application generates a "training set" called siStack based on a few training parameters and an input 3D surface mesh. Each surface mesh may require multiple "training sets" using differing parameters.

I envision my database to look like this: Table1 =name[ modelID modelName], Table 2 = parameters[ paramID modelID Param1 Param2 ...], Table 3 = trainingSet[ paramID siStack].

Is this possible, or even make sense? From what I read I need to use a BLOB type, but how do I convert my object to a BLOB and how to I later read the BLOB and convert it to a QList<siStore*>?

Thanks

[Lykurg]

Create a << and >> operator for your class siStore, then you can easily store your list siStack to a database and read it back in (using the operators...).

[agerlach]

That makes sense from what I have read, but how do I go about doing that? Could you give me a brief example?

[Lykurg]

Try something like that as a starting point

QDataStream& operator<<(QDataStream& stream, const  siStore& class)
{
   stream << siStore.siSum << class.si2Sum() << ...;
   return stream;
}

QDataStream& operator<<(QDataStream& stream, const  siStore& class)
{
   stream << siStore.siSum << class.si2Sum() << ...;
   return stream;
}

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[agerlach]

hmm... Unfortunately I'm away from my development PC and am unable to try your suggestion. But just to make sure I understand everything correctly, you would append all the members of my class to a QDataStream which would then be a binary encoding and could directly be used as a BLOB? Something like this, where siStack is a BLOB:

QSqlQuery query;
     query.prepare("INSERT INTO trainingSet (id, siStack) "
                   "VALUES (:id, :siStack)");
     query.bindValue(":id", 1001);
     query.bindValue(":siStack", myQDataStream);
     query.exec();

QSqlQuery query;
     query.prepare("INSERT INTO trainingSet (id, siStack) "
                   "VALUES (:id, :siStack)");
     query.bindValue(":id", 1001);
     query.bindValue(":siStack", myQDataStream);
     query.exec();

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