Using rules from related model

[Cyprian Kowalczyk]

Hi all,

Say we have a User that has many Addresses and only one address can be active (we have a rule(:active) on Address).

Can I currently do this `User.first.addresses.active` to get the active address?

kind regards,

Cyprian 

[Andreas Ronge]

Hi

Hmm, that would be nice.
We can't have a rule on the User which return an Address (I think).
But we can have a rule on the User class which return users which have
an active address (which is not what you want).

Maybe we could support it with something like this:
class User
has_n :addresses
rule(:active, :addresses) { |address| address.active? }
end

User.first.addresses.active #=> only active addresses

Will do some thinking ...
Cheers
Andreas

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[Cyprian Kowalczyk]

Hi Andres,

Such chaining would be possible if User.first.addresses would return Neo4j::Traversal::Traverser or if the return classes were otherwise standardized allowing method chaining for queries. Imagine all the flexibility it would allow. The construct should also allow execute a query on such chained calls.

Duplicating rules as you proposed in User is not really DRY.

kind regards,

Cyprian

On Tuesday, April 3, 2012 5:57:12 PM UTC+2, ronge wrote:

Hi

Hmm, that would be nice.
We can't have a rule on the User which return an Address (I think).
But we can have a rule on the User class which return users which have
an active address (which is not what you want).

Maybe we could support it with something like this:
  class User
    has_n :addresses
    rule(:active, :addresses) { |address| address.active? }
  end

  User.first.addresses.active #=> only active addresses

Will do some thinking ...
Cheers
Andreas

[Cyprian Kowalczyk]

Andreas, sorry for the typo in your name!

[Andreas Ronge]

Hi

User.first.addresses does already return a Traversal.
If the User and Address class were declared like this:
class Address < Neo4j::Rails::Model
rule(:active) { self[:active] == true}
end
class User < Neo4j::Rails::Model
has_n(:addresses).to(Address)
end
Then it would possible to (automatically) add the method "active" on
the Traversal returned by User.first.addresses which will check if the
Address nodes has an incoming relationship '_active' to the class node
(rule node).

Another alternative is top allow combining Rules/Travesal and Cypher queries.
Example:
User.all.addesses.query{|address| address.city == 'malmoe'}
Just some quick thoughts ...

Cheers
Andreas

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[Cyprian Kowalczyk]

Hi Andreas,

Isn't it that User.first.addresses returns `Neo4j::Rails::Relationships::NodesDSL`?

User.first.addresses.all woks, User.first.addresses.active does not.

kind regards,

Cyprian

On Friday, April 6, 2012 4:26:09 PM UTC+2, ronge wrote:

Hi

User.first.addresses does already return a Traversal.

If the User and Address class were declared like this:
  class Address < Neo4j::Rails::Model
     rule(:active) { self[:active] == true}
  end
  class User < Neo4j::Rails::Model
    has_n(:addresses).to(Address)
  end
Then it would possible to (automatically) add the method "active" on
the Traversal returned by User.first.addresses which will check if the
Address nodes has an incoming relationship '_active' to the class node
(rule node).

Another alternative is top allow combining Rules/Travesal and Cypher queries.
Example:
  User.all.addesses.query{|address| address.city == 'malmoe'}
Just some quick thoughts ...

Cheers
Andreas

> neo4jrb+unsubscribe@googlegroups.com.

[Andreas Ronge]

Hi

I've now started to look at this, it's probably not that hard to
implement (or at least some of it)
I've created a new issue https://github.com/andreasronge/neo4j/issues/181

Cheers
Andreas

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[Cyprian Kowalczyk]

Great! I'm looking forward to test it!

kind regards,
Cyprian

On 16 kwi 2012, at 12:30, Andreas Ronge wrote:

> Hi
>
> I've now started to look at this, it's probably not that hard to
> implement (or at least some of it)
> I've created a new issue https://github.com/andreasronge/neo4j/issues/181
>
> Cheers
> Andreas
>

[Andreas Ronge]

Hi

I'm making good progress on combining cypher, the traversal api and rules.
Check these RSpecs -
https://github.com/andreasronge/neo4j-wrapper/blob/master/spec/neo4j/rule/rule_cypher_integration_spec.rb

My favorite RSpec is this: "Give me all rooms in a dungeon where there
are dangerous monsters"
dungeon.monsters.dangerous { |m| rooms = m.incoming(Room.monsters); rooms }
This will create a cypher query for that (append a #to_s and you get
the cypher query as a String)

For simpler queries a hash value is supported, for example give me all
monsters with a weapon 'sword'
Monster.all(:weapon => 'sword')

Dangerous monsters are defined by a rule:

class Monster
include Neo4j::NodeMixin
property :age
rule :all
rule(:dangerous) { |m| m[:strength] > 15 }
end

Next - fix so this works from Neo4j::Rails::Model as well.

Btw, I removed the Neo4j::NodeIndex and merged into Neo4j::Node, same
with Neo4j::RelationshipIndex

Cheers
Andreas