Creating the same model from multiple data sources

Question

This is mostly of a design pattern question. I have one type of model that I'm going to get the data to create them from multiple sources. So for example one record my be created from an API where another is created via screen scraping with Nokogiri.

My issue lies in how best to abstract out these different data sources. Right now I'm building lib classes that return the same hash which I then use to set the attributes of the model. But I'm wondering if this isn't more of a case to use STI. Or if there is some other way of doing this I'm just not thinking about.

Answer 1

I think your design decision would depend largely on what attributes need to be stored. From your description, it sounds like you have a model with multiple data sources, but which would be storing the same attributes regardless of the source. In that case STI seems like overkill. When you retrieve a row from the table, does it matter whether the source is the API or the screen scraper? If not, then you could just define separate methods for each data source and use the appropriate method in the controller.

@instance = MyModel.new(:datasource=>"API")`

I'd say don't worry about inheritance (or mixing in code from modules) unless you really need to. There are some gotchas -- STI is not fully supported by some gems/plugins, for example.