Class definitions
A class definition specifies the attributes of the data stored in the datasets and the attributes of datasets. GeolinQ allows to add, modify and remove attributes from class definitions at any time. Inheritance of class definitions is applied to define the behaviour of the class definitions and to support the reuse of class definitions.
Categories of class definitions
Each class definition in GeolinQ is derived from Base Class. A base class might be a class definition provided by the GeolinQ system or a class definition specified by the user. A class definition will inherit the attributes and the behaviour of the base class. Inheritance will result in a hierarchy of class definitions that defines the data structure. GeolinQ provides two categories of base class definitions:
- Type class definitions to define the structure of the data stored in the datasets.
- Dataset class definitions to define the metadata structure of the datasets containing the data.
Attributes and constraints
Attributes specify the properties of a class definition. GeolinQ supports the following attribute types:
- GlReferenceAttribute: A reference to item in another dataset
- GlDateAttribute: A date without time
- GlDateTime: A data including a timestamp
- GlFloatAttribute: Numbers with a decimal point or a number in exponential form.
- GlIntegerAttribute: Numbers without decimals
- GlStringAttribute: Text field
- GlBoolAttribute: Boolean attribute ‘true’ or ‘false’
- GlColourAttribute: A RGB value of a color or a RGBA when transparency is supported.
Additional constraints can be enforced on attributes (e.g. required, value range, maximum length). Imported data is validated against these constaints to improve data quality. When validation fails, data is rejected and not stored in GeolinQ. In the task logging the user can see which records have been rejected and why.
Class hierarchy
The class hierarchy shows the class inheritance tree. When clicking on a class in the tree, the selected class and the derived classes are shown in the list with classes. When clicking on a class, a dialog appears showing the attributes of the class. When clicking of the Prperties tab, the properties of the class are shown.