Node Attributes

So I am designing a railsapp that indexes school organizations such as
clubs and frats/sororities. I have decided to represent this as a graph,
and that each entity is going to be just represented as a node, and the
relationship between each node is going to be an edge.

so basically, a frat such as “Alpha Beta Gamma” is represented as a
node, and its chapters also as seperate nodes, and pledge classes as
seperate nodes, then finally each member as a node. That’s easily done.

Now the hard part. I want each node to be able to be “tagged” with a
user specified attribute. this works out if I keep the attributes for
the tags one type. but i want different types such as :string, :text,
:date, :datetime, :boolean, etc for each.

for example, the root node of “Alpha Beta Gamma” would have the
attributes “established” with type :date, “history” with type :text,
etc, while an individual would have “firstname” and “lastname” as
string, “birthdate” as :date, etc.

There are two ways to represent this… i can do a polymorphic
associations to each type, such that i have an AttributeString model,
AttributeDate model, etc. which belongs to the Node model
polymorphically. Or what i can do is put all the Attributes in one
model, with a column in the database for every kind of type:
create_table :attributes do |t|
t.column :name, :string
t.column :type, :string
t.column :attr_string, :string
t.column :attr_text, :text
t.column :attr_integer, :integer
.
.
.

  t.column :attr_boolean, :boolean
end

so to access the attribute would be through a function that does a
switch against the type.

now, which way would be better? the polymorphic way, or the single table
way?

J.r. Gutierrez wrote:

user specified attribute. this works out if I keep the attributes for
AttributeDate model, etc. which belongs to the Node model
.

  t.column :attr_boolean, :boolean
end

so to access the attribute would be through a function that does a
switch against the type.

now, which way would be better? the polymorphic way, or the single table
way?

There’s a third way which might be easier. You can store the data in
YAML format. You can then use .to_yaml and YAML::load to set/get your
data. You’d only need a database table with two columns in that case the
key and the value.

A good example of this is the Settings plugin at:
http://beautifulpixel.textdriven.com/articles/2006/02/25/settings-plugin

take a look in lib/settings.rb.

Hope that helps.
dan

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