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views Split into two classes: one to handle config, other to do computation Aug 30, 2015
calculator.rb Move dentaku require to calculator class Aug 30, 2015

Dentaku Zen Garden


Dentaku Zen Garden is a sample project demonstrating the use of the Dentaku gem to allow some business logic to be moved outside of the source code of an application and safely evaluated at runtime.

The (contrived) scenario is running an ecommerce site to purchase the materials for enthusiasts to build miniature zen gardens according to shared plans. The catch is that the site allows the end user to specify custom dimensions and then calculates the required materials to construct a garden of that size. Additionally, the shipping weight is calculated from the material quantities and density formulas.


To get started, install the dependencies with bundler:

bundle install


To launch the application, execute app.rb:

bundle exec ruby app.rb

And view the application at http://localhost:4567

To configure your own custom zen garden, first choose a plan. Once a plan is selected, Dentaku will analyze the material requirements formulas and prompt you for the custom values required. After you provide these specific values, the application displays the required materials and the total calculated shipping weight.


All the data about projects and materials is stored in the db directory.

To define a new project, create a new CSV file in db/projects with one row per material component of your project, then add an entry to db/metadata.json

To redefine or add new helper formulas, edit the db/common_formulas.csv file.

All calculations are performed in calculator.rb. Metadata and formulas are loaded via the helper functions in project.rb.

The web UI (in Sinatra) is implemented in app.rb and the view templates are in views.