Generating Class Diagram from Models

Rails
1

Hi all!

There are several softwares which read a database and shows the
tables graphically on the screen (now I`m using Power Architect:
SQL Power Architect – Data Modeling). Is there something which
beyond to read the tables, can understand the relationship beetween it
from app/models files? I say, has_many, belongs_to, etc…

Ok, I could use Power Architect to read the tables and make the arrows
by hand, but in a constant growing project, it is not a good way.

Thank You
Tom L.

2

Hi Tom,

You read my mind, I just was about to post identical question… when
I stumped upon some complicated models legacy models today.

Is there something like that out there?

H.

3

Oh, alright. I guess it’s way past time to get my updates to my
model_graph code (http://rubyforge.org/projects/model-graph/) packaged
up and posted. This reflects on the AR associations and builds a DOT
file that can be visualized with, e.g., Graphviz. (From there you can
export as PNG, PDF, etc.)

-Rob

On Nov 21, 2008, at 10:51 AM, Hubert Łępicki wrote:

On 21 Lis, 15:31, Tom L. [email protected] wrote:

arrows
by hand, but in a constant growing project, it is not a good way.

Thank You
Tom L.

Rob B. http://agileconsultingllc.com
[email protected]
+1 513-295-4739
Skype: rob.biedenharn

4

Thanks Rob!

That is great script, I didn’t use Graphviz before so this was more
trouble than installing yor gem ;).

However, not sure if it’s my fault - or library works like that,
generated graph was hard to read and analyze, it also didn’t include
model attributes.

Googling for “ruby graphviz” was more successful:
http://visualizemodels.rubyforge.org/

Is really nice plugin, generates cool graphs. I just had to make
little fix for Rails 2.2 to work, but it’s easy.

Best,
H.

5

model_graph doesn’t do the attributes on purpose. My need was to
avoid redrawing the associations at a time on a particular project
where they were driving me a bit crazy. The use of decorated edges to
denote the kind of association is one thing that I didn’t find
elsewhere.

If you download the test file (or find it in the gem directory, I think)
http://model-graph.rubyforge.org/svn/model_graph_test.dot

and open it with Graphviz, you see the edge types that mean:

     class A < ActiveRecord::Base  # :nodoc:
       has_many :bs
       has_one :c
     end
     class B < ActiveRecord::Base  # :nodoc:
       belongs_to :a
     end
     class C < ActiveRecord::Base  # :nodoc:
       belongs_to :a
     end
     class One < ActiveRecord::Base  # :nodoc:
       has_and_belongs_to_many :twos
     end
     class Two < ActiveRecord::Base  # :nodoc:
       has_and_belongs_to_many :ones
     end
     class Alpha < ActiveRecord::Base  # :nodoc:
       has_many :betas
       has_many :gammas, :through => :betas
     end
     class Beta < ActiveRecord::Base  # :nodoc:
       belongs_to :alpha
       belongs_to :gamma
     end
     class Gamma < ActiveRecord::Base  # :nodoc:
       has_many :betas
       has_many :alphas, :through => :betas
     end
     class Selfish < ActiveRecord::Base  # :nodoc:
       has_many :selfishes, :foreign_key => :solo_id
     end

So a brief legend (in ASCII) would be:

-| belongs_to
-|o has_one
-o< has_many
dotted edge => has_many :through
-o<<>>o- has_and_belongs_to_many
(where <> is a small, unlabeled, diamond-shaped node)

Please do forward your fix for Rails 2.2!

Glad it helps a bit,

-Rob

On Nov 21, 2008, at 12:12 PM, Hubert Łępicki wrote:

Googling for “ruby graphviz” was more successful:

model_graph code (http://rubyforge.org/projects/model-graph/)

Hi Tom,

Hi all!
by hand, but in a constant growing project, it is not a good way.

Thank You
Tom L.

Rob B. http://agileconsultingllc.com
[email protected]

6

You can also try using RrailRoad (http://railroad.rubyforge.org/). I
find it pretty simple and neat. Note: It does not pick belongs_to
relationships and uses the has_many from the other direction for
figuring out relationships.