Mattias, Could you do something like Student --> Autumn 2009 --> Math A ? You could then easily also have Teacher --> Autumn 2009 --> Math A.
Jeremy On Fri, Feb 19, 2010 at 6:54 AM, Mattias Persson <matt...@neotechnology.com>wrote: > 2010/2/19 <rick.bullo...@burningskysoftware.com>: > > Mattias (and everyone) - can you see a way to model multiple > > relationships of the same type between two nodes? We have few cases > > where the relationship is essentially the same "type" but might have > > different properties. Max's "Class/Teacher" scenario is > > somewhat similar. > Yes, I've used such models a couple of times and it's a completely > valid usecase in some scenarios (not any particular comes to mind > though). > > You're suggesting something like: we have a "Math A" class node and > it'll have relationships to all teachers and students who have > attended that class? You would then "loose" the information about > which students have attended a specific class instance (f.ex. autumn > 2009 or something) with a specific teacher (if you don't store that > information on every Teacher ----> Class relationship and Student > ----> Class relationship). Did I understand you correct? > > > > > > > > Rick > > > > > > > > -------- Original Message -------- > > Subject: Re: [Neo] Choosing between a property or a node > > From: Mattias Persson <matt...@neotechnology.com> > > Date: Fri, February 19, 2010 4:27 am > > To: Neo user discussions <user@lists.neo4j.org> > > I've included some first thoughts on how you could model this. The > > choice of properties/index vs. relationships is often quite obvious, > > but is some cases you'll have to try and see which fits best. But > > neo4j encourages you to create relationships if you're in doubt and > > it's often better to use more relationships types than fewer, i.e. > > it's good to be as specific as possible when modelling your graph. > > 2010/2/19 Max De Marzi Jr. <maxdema...@gmail.com>: > > > Hello, > > > > > > What is the proper way to handle things that have only a few choices > > like: > > > > > > gender (male/female/unknown) > > > status (active, inactive, purged) > > > race(10 choices + other) > > > etc. > > > > > > As properties of a Person node, or as nodes that link to the Person > > node? > > > > > > Pros or Cons of each method? > > It depends on how you're querying the data... gender, status and race > > could probably be modelled using properties (and maybe indexed with > > IndexService, see [1]http://components.neo4j.org/neo4j-index/) since > > you > > would use them as filters in queries. But if you're planning to do > > traversals which will bridge persons over to other persons (or other > > entities) via f.ex. status, then relationships would be handier. > > > > > > How about something with instances? > > > > > > Student took a Class (twice) once with This teacher, once with > > Another > > > Teacher. > > > > > > The first time he failed, the second time he got a B. > > > > > > Create a StudentClass node with a property of Grade, linked to > > Teacher? > > Yes, have each student as a node. Each class instance as a node with > > TEACHES_IN relationship to teacher (and maybe CLASS_TYPE relationship > > to what type of class the class instance is). Have a TAKES_CLASS > > relationship between student and class instance and set grade property > > on that relationship. > > > > > > In order to answer: > > > > > > Find all students who took the class. > > Relationships between student and class. > > > Find all students who took the class when it was offered in the > > spring > > > semester (or taught by This Teacher). > > Start from either a teacher node (and go to the class instance) or > > from a class instance. They can be lookup up from and IndexService or > > something) and get relationships to students from there. > > > Find all students who got a B > > If you create nodes for each grade available and create relationships > > to those grade nodes whenever a student gets a grade. Then it'd be > > easy to just get that "B" grade node and traverse all its > > relationships to students. Otherwise you could index the grade > > property from the ATTEND_CLASS relationships (see above) for the > > student nodes. > > > Find all students to got a B in this class? > > Start from the class and traverse out to all its class instances and > > students, filtering those who got a B (using the grade property on > > ATTEND_CLASS relationships). > > > Find all students to got a B in this class during the spring > > semester? > > Same as previous but only traverse those class instances which were > > offered in spring semester. > > > Find all students to got a B in this class when This Teacher taught > > it? > > Start from either the teacher node or the class node and find the > > class instance for that class which the teacher has a relationship to. > > And tou get the students from there. > > I hope this will help you, > > Best, > > Mattias > > _______________________________________________ > > Neo mailing list > > User@lists.neo4j.org > > [2]https://lists.neo4j.org/mailman/listinfo/user > > > > References > > > > 1. http://components.neo4j.org/neo4j-index/ > > 2. https://lists.neo4j.org/mailman/listinfo/user > > _______________________________________________ > > Neo mailing list > > User@lists.neo4j.org > > https://lists.neo4j.org/mailman/listinfo/user > > > > > > -- > Mattias Persson, [matt...@neotechnology.com] > Neo Technology, www.neotechnology.com > _______________________________________________ > Neo mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user > _______________________________________________ Neo mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
