DataBuilder

The goal of DataBuilder is to apply an expressive means of constructing a data set based on information stored in YAML files.

Installation

To get the latest stable release, add this line to your application's Gemfile:

gem 'data_builder'

And then include it in your bundle:

$ bundle

You can also install DataBuilder just as you would any other gem:

$ gem install data_builder

Usage

DataBuilder is using my DataReader gem to provide base-level functionality. Unlike DataReader, DataBuilder will assume some defaults. For example, you could do something as simple as this:

require "data_builder"

data = DataBuilder.load 'default.yml'

puts data

Here I'm relying on the fact that DataBuilder applies a default directory of data. I then use the load method of DataReader to call up a file in that directory. I could set my own data path with DataBuilder as such:

require "data_builder"

DataBuilder.data_path = 'config/data'
data = DataBuilder.load 'default.yml'

puts data

Here you can inform DataBuilder where it can find the data files using data_path. As you've seen, if you don't specify a directory then DataBuilder will default to using a directory named data.

After setting the directory you must load a file. This can be accomplished by calling the load method.

DataBuilder.load 'default.yml'

However, these approaches are really just using DataBuilder as an overlay for DataReader.

Where DataBuilder steps in is when you want to use the data. DataBuilder provides a data_about method that will return the data for a specific key from any data files that have been loaded.

The most common way to use this is to include or extend the DataBuilder module. Let's say that you have a data directory and in that directory you have a file called default.yml. The YAML file has the following contents:

alpha centauri:
  warpFactor: 1
  velocity: 2
  distance: 4.3

epsilon eridani:
  warpFactor: 1
  velocity: 2
  distance: 10.5

Now let's use DataBuilder to get the information from it.

Extending DataBuilder

class Testing
  extend DataBuilder
end

data = Testing.data_about('alpha centauri')

Including DataBuilder

class Testing
  include DataBuilder
end

testing = Testing.new
data = testing.data_about('alpha centauri')

The Data Key

In both cases of extending or including, I'm using a variable to store the results of the call. Those results will be the data pulled from the default.yml file. Of note, however, is that all that will be pulled is the data from the "alpha centauri" key because that is what you specified in the call to data_about.

In these examples, I'm using a string because the value "alpha centauri" has a space in it. However, if that was not the case -- if the key were, say, alpha_centauri -- then you could use a symbol instead, like this:

data = testing.data_about(:alpha_centauri)

Default Files

You might wonder how DataBuilder knew to look for default.yml since I didn't use a load method in these examples. If you do not specify a filename the logic will attempt to use a file named default.yml in the data path you have specified or in the default path of data.

Another option is that you can set an environment variable called DATA_BUILDER_SOURCE. When this variable exists and is set, the value it is set to will be used instead of the default.yml file. Keep in mind that the "data source" here refers to the file, not the keys within a file.

Namespaced Data

To organize your data into a rough equivalent of namespaces, and to load that data accordingly, you can do something like this:

class Testing
  include DataBuilder
end

testing = Testing.new

data = testing.data_about('stars/epsilon eridani')

When DataBuilder sees this kind of construct, it will take the first part (before the /) as a filename and the second part as the key to look up in that file. So the above command would look for a file called stars.yml in the data path provided and then grab the data from the key entry labeled "epislon eridani".

Aliases

Given the examples, you can see that data_about was chosen as the method name to make what's occurring a bit more expressive. You can use the following aliases for data_about:

• data_from
• data_for
• using_data_for
• using_data_from

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec:all to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment. To install this gem onto your local machine, run bundle exec rake install.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/jnyman/data_builder. The testing ecosystem of Ruby is very large and this project is intended to be a welcoming arena for collaboration on yet another testing tool. As such, contributors are very much welcome but are expected to adhere to the Contributor Covenant code of conduct.

To contribute to DataBuilder:

1. Fork the project.
2. Create your feature branch. (git checkout -b my-new-feature)
3. Commit your changes. (git commit -am 'new feature')
4. Push the branch. (git push origin my-new-feature)
5. Create a new pull request.

Author

• Jeff Nyman

Credits

This code is loosely based upon the DataMagic gem. I created a new version largely to avoid the name "magic", which I don't think any tool should be promoting. I'm also cleaning up the code and documentation.

License

DataReader is distributed under the MIT license. See the LICENSE file for details.