QEAnnotation

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.

1. How to use custom annotations
2. Models and Annotation singleton
3. Installation
4. Versioning
5. License

How to use custom annotations

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>();

Models and Annotation singleton

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.

Installation

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.

Versioning

This library uses Semantic Versioning and internal private implementation to provide a long-term, stable, and reusable binaries.

License

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