Modeling: User's Guide

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3.3.1 Integrity constraints derived from the underlying model

When you define a model, you also define a number of constraints that has to be checked. For example, lower- and upper- bounds of a relationship's multiplicity, say (min=1, max=3), specify that an object cannot have less than one object (of a certain type!) in relation with itself, and no more than three as well. You can also mark an attribute as 'required' to avoid it being None.

The framework naturally verifies these constraints: the checking occurs automatically when an EditingContext is about to save changes (we will see hereafter how this can be manually triggered).

The constraints that are enforced are the following:

• Attributes:
  • type of the stored value,
  • if it is marked as 'required', it shouldn't be None
• Relationships:
  • the type of the objects in relation with oneself,
  • the number of objects in relation vs. the relationship's multiplicity.

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Modeling: User's Guide

Previous: 3.3 Automatic validation of Up: 3.3 Automatic validation of Next: 3.3.2 Checking constraints: key

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Release 0.9, documentation updated on March 4, 2006.

Comments are welcome: Sebastien Bigaret / Modeling Home Page
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