With spring data neo4j you are able to use any domain entity with any node, so
it is for instance
possible to project an entity to another when used in a different context.
Otherwise the Spring Data Neo4j config less invasive and more concise than the
existing model
but uses the same approach behind the scenes (fields are mapped to properties
and relationships - 1:1 or 1:n are mapped to relationships).
@NodeEntity
class Movie {
String title;
Set<Actor> actors;
}
a more elaborate example.
@NodeEntity
class Movie {
@GraphId Long id;
@Indexed(fulltext=true, indexName="movies") String title;
@RelatedToVia(type="ACTS_IN", direction=Direction.INCOMING)
Iterable<Role> roles;
Person director;
}
@RelationshipEntity
class Role {
@Indexed String title;
@StartNode Actor actor;
@EndNode Movie movie;
}
@NodeEntity
class Actor {
String name;
Gender gender;
Date birthday;
public Role actsIn(Movie movie, String role) {
return relateTo(movie,"ACTS_IN",Role.class).withTitle(role);
}
@RelatedTo(type="ACTS_IN")
Set<Movie> movies;
}
Am 14.10.2011 um 16:14 schrieb Thad Guidry:
> I would suggest breaking down his statement further and fill in the blanks
> to gain even better insight into his conjecture.
>
> "it‘s basically a bunch of nodes where you just blob your attributes.‘
> Worse than that, to wrap objects around it, you have to have them explicitly
> incorporate their node class, which is ugly, smelly, violates every law of
> separation of concerns and logical vs. physical models."
>
>
> "it's" - Neo4j
>
> "to wrap objects around IT" - what is the IT that he is referring to ?
>
> "you have to have THEM explicitly incorporate THEIR node class" - what is
> THEM / THEIR really mean for Neo4j here ?
>
> "law of separation of concerns" - what and where are we JOINING that should
> be SEPARATING , is it only the Domain objects ?
>
>
> From outside looking in, I have seen others not complete their Domain Model
> as needed with Neo4j, and also make it entirely TOO SIMPLE. Why ? Because
> they might be new to graph databases, or their Domain Model really IS NOT
> complete yet and they need help from others to assist with putting together
> an elegant Domain Model to begin with. Being able to easily wire up a
> Domain Model is the primary reason they were attracted to graph databases in
> the first place !... to build it out without resorting to defining a rigid
> schema (a SQL table mantra). But many need help in contorting their Domain
> Model over time. To me, Neo4j is already wide open enough to handle that
> contortion and the beauty of Neo4j & graph databases in general.
>
> Folks just need better much more detailed Domain Model examples than what is
> available, that would help incredibly so, since many folks have a complex
> Domain Model to begin with (they just do not realize it yet) and they are
> hoping Neo4j will help them quickly wire it up, stretch it out when needed,
> and analyze the hell out of it when the time comes, and stretch it out even
> more as they continue to fill it up and expand their Domain Model. A bottom
> up approach (and I mean really BOTTOM) is the best practice, but it does
> take thought and research in finding where that generic bottom is at. A
> "Friend" - what is a Friend, what attributes does a Friend have ? Which ones
> do I care about now and can worry about later ? A "Stock Issuing Company",
> do I need to think of my relationships first for those, or should I start
> with attributes ? Will those attributes be shared with others ? Do I care
> about it now at this early beginning of my Domain Model, or can I wait on
> this ? Should I start with attributes (properties) always, and leave
> relationships alone until the very end, when I build a Domain Model ? (the
> answer to that last question is YES, because Neo4j actually DOES allow you
> to)
>
>> He attacks our pattern of building domain models with Neo4j, calling it
>>> "ugly", "smelly" and "in violation of every law of separation of concerns
>>> and logical vs. physical models". Is he right? My feeling is that he is
>>> brain washed with too many so called "best practices", but Neo4j has been
>> my
>>> main model for a long time now, my perspective is likely skewed. I'd like
>> to
>>> hear your thoughts.
>>
>
> Your main model IS NOT Neo4j. That is your main database that "holds" your
> Domain Model. And if Neo4j is not really doing this from top to bottom,
> then I would agree with Richard that the Neo4j infrastructure is not in the
> best place right now and might need more work.
>
> --
> -Thad
> http://www.freebase.com/view/en/thad_guidry
> _______________________________________________
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> [email protected]
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