Model inheritance and relationships exception

[kichael]

Setting a relationship on a model that inherits from another model
causes an exception.

For example:

class BizProcess < Neo4j::Rails::Model
property :title, :type => String
end

class Innovation < BizProcess
has_n(:deps).to(Department)
end

class Department < Neo4j::Rails::Model
property :name, :type => String
index :name

has_n(:innovations).from(Innovation, :deps)
end

Then when typing 'Innovation' in rails console:
> Innovation
LoadError: Expected /app/models/innovation.rb to define Innovation

In the stack trace down the line it points to the issue being the line
in the Department model that defines the relationship.

When setting Innovation to inherit from Neo4j::Rails::Model, the
problem goes away, but that's not an acceptable solution.

One workaround I've used it defining it in the BizProcess model, but
this is confusing to others.

Is this by design or is this an issue?

Thanks,

Michael

[Andreas Ronge]

Hi

Interesting. Looks like an issue.
Maybe it is related to how rails is loading undefined constants/classes.

Can you try just using plain Ruby classes without any inheritance from
Neo4j::Rails::Model
and see if the same problem occurs ?

Something like this:

biz_process.rb:
class BizProcess
end

innovation.rb:
class Innovation < BizProcess
puts Department
end

department.rb:
class Department
end

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[kichael]

When I changed the classes to how you specified:

> Innovation
Department
=> Innovation

[Andreas Ronge]

Good, I've created another ticket
http://neo4j.lighthouseapp.com/projects/15548-neo4j/tickets/184-inheritance-for-neo4jrailsmodel-does-not-work-in-rails

If someone wants help out there are some bugs that needs to be fixed:
http://neo4j.lighthouseapp.com/projects/15548-neo4j/tickets

The easiest to solve is probably:
http://neo4j.lighthouseapp.com/projects/15548/tickets/183-init_on_create-is-not-called-when-creating-a-new-relationship-with-the-operator

/Andreas

[Andreas Ronge]

Hi

I can't reproduce this bug and I'm therefore not sure it is a bug,

Here is what I did.

1. Create a new rails project
rails new qwe -m http://andreasronge.github.com/rails3.rb

2. Create the three model classes:
models/
|-- biz_process.rb
|-- department.rb
`-- innovation.rb

biz_process.rb:

class BizProcess < Neo4j::Rails::Model
property :title, :type => String
end

innovation.rb:

class Innovation < BizProcess
has_n(:deps).to(Department)
end

department.rb:

class Department < Neo4j::Rails::Model
property :name, :type => String
index :name
has_n(:innovations).from(Innovation, :deps)
end

4. Start the rails console: rails s

5. Type rails c
Loading development environment (Rails 3.1.0)
jruby-1.6.4 :001 > Innovation
=> Innovation
jruby-1.6.4 :002 > Innovation.create
Enable remote shell at port port=9332
Starting local Neo4j using db /home/andreas/tmp/qwe/db/neo4j-development
=> #<Innovation:0x3ee0b7 @errors=#<ActiveModel::Errors:0x1af431c
@base=#<Innovation:0x3ee0b7 ...>, @messages=#<OrderedHash {}>>,
@changed_attributes={}, @properties={"_classname"=>"Innovation"},
@_java_node=#<#<Class:0x1015fd4a3>:0x911b9f>, @relationships={},
@previously_changed={"_classname"=>[nil, "Innovation"]},
@validation_context=nil>

/Andreas

[kichael]

After looking into it to reproduce the bug, one needs to add any
relationship definition to BizProcess.

So even adding a has_n(:departments).to(Department) to BizProcess
would suffice to reproduce. But any relationship to any model seems to
trigger it. Once I comment out all the relationships in BizProcess,
the issue goes away.

On Sep 22, 10:00 am, Andreas Ronge <andreas.ro...@gmail.com> wrote:
> Hi
>
> I can't reproduce this bug and I'm therefore not sure it is a bug,
>
> Here is what I did.
>
> 1. Create a new rails project

>   rails new qwe -mhttp://andreasronge.github.com/rails3.rb

[Andreas Ronge]

Ok, I have managed to reproduce this bug without using neo4j.rb with this:
class Department
puts "Department #{Innovation}"
end

class Innovation < BizProcess
puts "Innovation #{Department}"
end

class BizProcess
puts "BizProcess #{Department}"
end

I suggest that you in the innovation.rb file does a forward
declaration of BizProcess
innovation.rb:

class BizProcess < Neo4j::Rails::Model

end

class Innovation ...

biz_process.rb:
# open up the BizProcess again and add all your properties and has_n etc...

Is that a good enough work around ?

/Andreas

[kichael]

That didn't work for me, as I could not access the various
relationships defined in BizProcess through an Innovation.

My files look like this with your suggested changes:

innovation.rb
class BizProcess < Neo4j::Rails::Model
end

class Innovation < BizProcess

has_n(:deps).to(Department)

end

department.rb
class Department < Neo4j::Rails::Model
property :name, :type => String

has_n(:biz_processes).from(BizProcess, :departments)
has_n(:innovations).from(Innovation, :deps)
end

biz_process.rb
class BizProcess < Neo4j::Rails::Model
property :title, :type => String

has_n(:departments).to(Department)
end

When I try to do innovation.departments, I get 'undefined method
`departments' for #<Innovation:0x4eb525a6>'

Is this what you meant by forward declaration or did I misread
somewhere?

Thanks,

Michael