It is the Annotation library in QE Framework. It allows you to annotate easily QObject classes and access to a model class that represents its custom annotation.
Let's assume that we are using an ORM that uses annotations to make relations between objects in memory and your database. Our first step is to annotate the classes. QEAnnotation uses Q_CLASSINFO Qt macro to add annotations to a property. In this example, we will use the 'book' concept.
class Book : public QObject
{
Q_OBJECT
Q_CLASSINFO( "class", "@qe.model.name=book")
Q_PROPERTY( int id MEMBER id)
Q_CLASSINFO( "id", "@qe.entity.isAutoIncrementable=true @qe.entity.name=bid")
Q_PROPERTY( QString title MEMBER title)
Q_CLASSINFO( "title", "@qe.entity.maxLength=256")
Q_PROPERTY( QString author MEMBER author)
Q_CLASSINFO( "author", "@qe.entity.maxLength=512")
public:
int id = 0;
QString title;
QString author;
};In the above example code, we have the following annotation over properties:
-
On 'id' property:
- @qe.entity.isAutoIncrementable = true
- @qe.entity.name = bid
-
On 'title' property:
- @qe.entity.maxLength = 256
You can create as much annotations as you want, but they MUST start with @ character.
In order to access those annotations from your code, you only need to load the model of this class using the singleton {{qe::annotation::Annotation}}.
// In your code...
using qe::annotation;
// ...
Model bookAnnModel = Annotation::registerModel<Book>();
bool isIdAuto = bookAnnModel.annotation( "id", "@qe.entity.isAutoIncrementable")
.value().toBool();
int maxLength = bookAnnModel.annotation( "title", "@qe.entity.maxLength")
.value().toInt();Annotation::registerModel<Book>();Model class uses implicit sharing concept, so you can copy efficiently objects.
Also Annotation class caches the models associated to any specific class. In this way, only first load will parse the annotations.
The easiest way to use this library in your code is by Conan Package Manager. Please use the project setup that you can find in QEAnnotation/1.0.0 Conan.
This library uses Semantic Versioning and internal private implementation to provide a long-term, stable, and reusable binaries.
This license follows the dual-license pattern that Qt is currently using. A LGPL 3.0 license for projects that do not need commercial support, and another one, Commercial license for rest of cases.
You can find a brief comparison between both licenses in the below table:
| License types | LGPLv3 | Commercial |
|---|---|---|
| Community Support | Yes | Yes |
| Official Support Helpdesk | No | Yes |
| Keep your application private | No | Yes |
| Possible to keep your application private with dynamic linking | Yes | Yes |
| No need to provide a relinking mechanism for QE Framework (can always use static linking) |
No | Yes |
| No need to provide a copy of license and explicitly acknowledge the use of QE |
No | Yes |
| No need to make copy of the QE Framework source code available for customers |
No | Yes |
| Full rights to proprietary QE source code modifications | No | Yes |
| Enforce DRM | See LGPLv3 FAQ | Yes |
| Enforce software patents | See LGPLv3 FAQ | Yes |