Relationships

From Pengower
Jump to: navigation, search

Relationships enables you to create a link between two different Types. This allows a Type to access data from another Type.

Standard Type/Type Relationships

Relationships.jpg

Illus 9.jpg


Title

This is the relationship title and is used to identify the relationship.

Description

This is a place for the designer to make design notes about this relationship.

Left Type

Select the Left Object from the Left Object dropdown list. This provides the left hand side of the object/object relationship.

Right Type

Select the Right Object from the Right Object dropdown list. This provides the right hand side of the object/object relationship.

Left to Right Label

Type in the left to right relationship label (descriptor). The example shown above shows that the left type (member) belongs to the right type (employee).

Right to Left Label

Type in the left to right relationship label (descriptor). The example shown above shows that the right type (employee) contains the left type (member).

Cardinality


Illus 11.jpg


The cardinality dialogue shows the number of left and right objects that can exist in the relationships. In the examples shown here there can be many Type 1 objects (Member) in the relationship, but only one Type 2 object (Employee).


Other Type to Type relationship cardinalities include:

  • One to One (Eg. Employee located at Desk)
  • One to Many (Eg. Employee creates Timesheets)
  • Many to Many (Eg. Person passenger on Flight)


Multi Dimensional Relationships

As well as having relationships between types, it is also possible to create a relationship between one relationship and another - which has the effect of creating multidimensional relationships between Types. As an example, a Person object is shown to have a relationship (knows) with another Person object. In fact it is a many to many relationship in the sense that a Person can know many other Persons (people) which in reverse can be known by. In addition each “Person knows Person” relationship that is created has a relationship with the Relationship Type (Eg. Family Member, University Friend, Ex-Colleague.Etc.) – this example shows how three objects can be directly linked to each other to form a three dimensional object cluster but in fact higher dimensional relationship cluster could also be formed if required.

Creating and Editing Relationships

To learn how to create and edit Relationships between Types, watch our tutorial on How to Relate Types

Application

You can see how Relationships between Types are created and used in this video below:


See Also

Types

How to create Types

How to display a related Type in an Element

How to display an Element from a Related Type