InferModel

Infer a model from data.

This gem transforms data dumps into managable structures.

You can use it to deduce certain properties from a given set of data to use it to build a database around this data.

The main use case is: Given a csv file that was exported from some tool, you want to manage and process the contained data in a database, say in your rails application. It would be valid to create a string column for every CSV column and import the data as is but you lose a lot of information by doing so.

Instead what this tool allows you to do is to guess which data type, like integer, decimal, boolean, etc, is the best fit for each column and allows you to create migrations or scripts to do so almost automatically.

Additionally the values may be parsed to deduce further features of your data that may be useful when setting up a database, like uniqueness or non-null constraints.

Install the gem and add to the application's Gemfile by executing:

$ bundle add infer_model

If bundler is not being used to manage dependencies, install the gem by executing:

$ gem install infer_model

A CLI is yet to be written. But you may run the tool from inside your code or an interactive session.

Run code like the following:

require "infer_model"

# Just display the results in a human readable format
InferModel.from(:csv, "path/to/file.csv").to(:text).call

# Create a rails migration for me with the inferred information
InferModel.from(:csv, "path/to/file.csv", csv_options: { col_sep: ";", encoding: "csp1252" }).to(:migration, rails_version: "6.0", table_name: "csv_contents").call

More "Adapters" that can be used as from source or to target may be added in the future. If you have ideas or needs please contribute by creating an issue or pr.

After generating a database table fitting to your data, you might want to fill them. You can use InferModels parsers to do so. For example in your rails app, in an import service or seeds:

now = Time.current
column_types = MyModel.columns.to_h { |column| [column.name, column.type] }

data = ::CSV.foreach("my_model_data.csv", col_sep: ";", encoding: "utf-8", headers: true, header_converters: :symbol).map do |row|
    parsed_attributes = row.to_h.to_h do |column_name, value| # note the `to_h.to_h`: The first one turns the row into a hash, the second one allows building a new hash with the block. CSV::Row's #to_h method does not process the block properly.
        column_type = column_types.fetch(column_name.to_s)
        parser = InferModel::Parsers::BY_TYPE.fetch(column_type)
        [column_name, parser.call(value)]
    end
    { created_at: now, updated_at: now }.merge(parsed_attributes)
end

MyModel.upsert_all(data) if data.present? # rubocop:disable Rails/SkipsModelValidations

That way you profit from the parsers logic that already generated your tables. For example the Boolean parser acknowledges "Y" as a truthy value compared to "N" which is considered falsey. When you use a different parser or just attempt to insert the string value into your database, they will most likely all have true as value in the corresponding column just because "N" is considered truthy.

For more information on how different parsers work, have a look inside their definition, e.g. the constants InferModel::Parsers::Boolean::TRUTHY_VALUES_LOWERCASE and FALSEY_VALUES_LOWERCASE. There might be the option to configure those values in the future.

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec 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. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/Jay-Schneider/infer_model. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

The gem is available as open source under the terms of the MIT License.

Everyone interacting in the InferModel project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.