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POQuestions about implementing Domain class relationships & constraints in Grails
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copied!<p>Using ArgoUML, I very quickly created this trivial representation of a few Domain classes (Person, Store, Product) and their relationships. <a href="http://img411.imageshack.us/img411/715/soquestion.png" rel="nofollow noreferrer">UML Model http://img411.imageshack.us/img411/715/soquestion.png</a> </p> <p>I'm struggling with the implementation of the relationships. Below was my initial approach for the Person domain, but it seems that I am missing something important. </p> <pre><code>class PersonToPerson { Person from Person to String relation static constraints = { relation(inList:["Friend to", "Enemy of", "Likes", "Hates"]) } static belongsTo = [ Person ] } class Person { String firstName String secondName . . . static hasMany= [ personToPerson:PersonToPerson, personToStore:PersonToStore ] } </code></pre> <p><strong>Edit: updated question for clarity</strong></p> <hr> <p>After thinking on the problem I think I have a better way to ask the question(s). In the implementation of PersonToPerson above I have the relation as a simple string. I want the user to be able to select from a list of unique relations, which are defined in the constraints, for the string value for PersonToPerson. So this leads to the questions...</p> <ol> <li>Should personToPerson and personToStore be consolidated into one list of type Relationship? Or should they stay independent lists as shown?</li> <li>What is the mechanism to allow the user to add new values to the relation constraint?</li> </ol>

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