qdjango foreign keys - qt

Question

Quick googling returned no results on how to properly use QDjango's Foreign Keys - there are functions
QDjangoModel::foreignKey and QDjangoModel::setForeignKey - but I couldn't find any good examples on how to use them in practice.

Answer 1

Its quite old, maybe will help someone else.. I searched for FKs in QDjango for eons and found something in google group, there is also nice documentation with some basic examples(but no FK examples)
I create table models using QDjango in this way (also foreign keys):
class Role : public QDjangoModel { ... };
class User : public QDjangoModel
{
Q_OBJECT
Q_PROPERTY(QString name READ name WRITE setName)
Q_PROPERTY(QString password READ password WRITE setPassword)
Q_PROPERTY(Role *role READ role WRITE setRole)
Q_CLASSINFO("name", "max_length=255")
Q_CLASSINFO("password", "max_length=255")
Q_CLASSINFO("role", "on_delete=cascade")
QString mName;
QString mPassword;
public:
User(QObject *parent = 0);
QString name() const { return mName; }
void setName(QString name) { mName = name; }
QString password() const { return mPassword; }
void setPassword(QString pass) { mPassword = pass; }
Role *role() const;
void setRole(Role *role);
};
You can use Q_CLASSINFO to set some attributes to columns.
The foreign keys are bound in constructor and filled in role functions.
User::User(QObject *parent)
: QDjangoModel(parent)
{
setForeignKey("role", new Role(this));
}
Role *User::role() const
{
return qobject_cast<Role *>(foreignKey("role"));
}
void User::setRole(Role *role)
{
setForeignKey("role", role);
}
When you want to select using fields from fk dependant table use two undescores and of course use selectRelated() (which just sets some flag which is later used to produce join select) like:
QDjangoQuerySet<User> matched;
matched = matched.selectRelated()
.filter(QDjangoWhere("role__rolename", QDjangoWhere::Equals, "admin"));