Csv2Hash

(Travis CI)

It is a DSL to validate and map a CSV to a Ruby Hash.

Installation

Add this line to your application's Gemfile:

gem 'csv2hash'

And then execute:

$ bundle

Or install it yourself as:

$ gem install csv2hash

Usage

Parsing is based on rules, you should defined rule for each cells

DSL

  Csv2hash::Main.generate_definition :name do
    set_type { Definition::MAPPING }
    set_header_size { 2 } # 0 by default
    set_structure_rules {{ 'MaxColumns' => 2 }}
    mapping do
      cell position: [0,0], key: 'gender'
      cell position: [1,0], key: 'name'
    end
  end
  Csv2hash::Main[:name] # Access anywhere

Rules

You should declared a definition of your CSV file, and then define for each cell what you would expect.

Example :

If you want the very first cell, located on the first line and on the first column to be a string with values are either 'yes' either 'no', you can write the following validation rule:

    cell name: 'aswering', type: 'string', values: ['yes', 'no'], position: [0,0]

:type attribute has String for default value, therefore you can just write this:

    cell name: 'aswering', values: ['yes', 'no'], position: [0,0]

You can define you own message but default message is 'undefined :key on :position'

    cell name: 'aswering', values: ['yes', 'no'], position: [0,0], message: 'this value is not supported'

You can also define Range of values

    cell name: 'score', values: 0..5, position: [0,0]

The message is parsed:

    cell ..., message: 'value of :name is not supported, please you one of :values'

It produces :

    value of answering is not supported, please use one of [yes, no]

Default values

Only position is required:

• :position

All remaining keys are optionals:

• message: 'undefined :key on :position'
• mappable: true
• type: 'string'
• values: nil
• nested: nil
• allow_blank: false
• extra_validator: nil

Define where your data is expected

IMPORTANT! Position means [Y, X], where Y is rows, X columns

A definition should be provided. There are 2 types of definitions:

• search for data at a precise position in the table: y,x
• or search for data in a column of rows, where all the rows are the same: x (column index)

Samples

[MAPPING] Validation of cells with defined precision

Consider the following CSV:

Fields	Person Informations	Optional
Nickname	jo	no
First Name	John	yes
Last Name	Doe	yes

Precise position validation sample:

    class MyParser

        attr_accessor :file_path_or_data

        def initialize file_path_or_data
            @file_path_or_data = file_path_or_data
        end

        def data
            @data_wrapper ||= Csv2hash::Main.new(Csv2hash::Main[:<definition_name>], file_path_or_data).parse
        end

        private

        def definition
          Main.generate_definition :my_defintion do
            set_type { Definition::MAPPING }
            set_header_size { 1 }
              mapping do
                cell position: [2,1], key: 'first_name'
                cell position: [3,1], key: 'last_name'
              end
            end
          end
        end

    end

[COLLECTION] Validation of a collection (Regular CSV)

Consider the following CSV:

Nickname	First Name	Last Name
jo	John	Doe
ja	Jane	Doe

Collection validation sample:

    class MyParser

        attr_accessor :file_path_or_data

        def initialize file_path_or_data
            @file_path_or_data = file_path_or_data
        end

        def data
            @data_wrapper ||= Csv2hash::Main.new(Csv2hash::Main[:<definition_name>], file_path_or_data).parse
        end

        private

        def definition
            Csv2Hash::Definition.new(rules, type = Csv2Hash::Definition::COLLECTION, header_size: 1)
        end

        def definition
          Main.generate_definition :my_defintion do
            set_type { Definition::COLLECTION }
            set_header_size { 1 }
              mapping do
                cell position: 0, key: 'nickname'
                cell position: 1, key: 'first_name'
                cell position: 2, key: 'last_name'
              end
            end
          end
        end

    end

Structure validation rules

You may want to validate some structure, like min or max number of columns, definition accepts structure_rules as a key for the third parameter. Current validations are: :min_columns, :max_columns

  class MyParser

    attr_accessor :file_path_or_data

    def initialize file_path_or_data
        @file_path_or_data = file_path_or_data
    end

    def data
        @data_wrapper ||= Csv2hash::Main.new(Csv2hash::Main[:<definition_name>], file_path_or_data).parse
    end

    private

    def definition
      Main.generate_definition :my_defintion do
        set_type { Definition::COLLECTION }
        set_header_size { 1 }
        set_structure_rules {{ min_columns: 2, max_columns: 3 }}
          mapping do
            cell position: 0, key: 'nickname'
            cell position: 1, key: 'first_name'
            cell position: 2, key: 'last_name'
          end
        end
      end
    end
  end

CSV Headers

You can define the number of rows to skip in the header of the CSV.

    set_header_size { 1 }

Parser and configuration

Pasrer can take several parameters like that:

    definition, file_path_or_data, ignore_blank_line: false

in file_path_or_data attribute you can pass directly an Array of data (Array with 2 dimensions) really useful for testing, if you don't care about blank lines in your CSV you can ignore them.

Response

The parser return values wrapper into DataWrapper Object, you can call .valid? method on this Object and grab either data or errors like that :

    response = parser.parse
    if response.valid?
        response.data
    else
        response.errors
    end

data or errors are Array, but errors can be formatted on csv format with .to_csv call

    response.errors.to_csv

Exception or Not !

You can choose into 2 differents modes of parsing, either break_on_failure mode for throw an exception when rule fail or csv mode for get csv original data + errors throwing into added extra column.

On BREAK_ON_FAILURE MODE

You need call .parse() with bang !

On CSV MODE

You need call .parse() return data_wrapper if .parse() is invalid, you can code your own behavior:

in your code

    parser = Csv2hash::Main.new(definition, file_path_or_data, ignore_blank_line: false).new
    response = parser.parse
    return response if response.valid?
    # Whatever

In the same time Csv2hash call notify(response) method when CSV parsing fail, you can add your own Notifier:

    module Csv2hash
        module Plugins
            class Notifier
                def initialize csv2hash
                    csv2hash.notifier.extend NotifierWithEmail
                end

                module NotifierWithEmail
                    def notify response
                        filename = 'issues_errors.csv'
                        tempfile = Tempfile.new [filename, File.extname(filename)]
                        File.open(tempfile.path, 'wb') { |file| file.write response.errors.to_csv }
                        # Send mail with csv file + errors and free resource
                        tempfile.unlink
                    end
                end
            end
        end
    end

Or other implementation

Errors Format

errors is a Array of Hash

    { y: 1, x: 0, message: 'message', key: 'key', value: '' }

Sample

Csv data

Fields	Person Informations
Nickname	nil

Rule

    cell position: [1,1], key: 'nickname', allow_blank: false

Error

    { y: 1, x: 1, message: 'undefined nikcname on [0, 0]', key: 'nickname', value: nil }

Personal Validator Rule

You can define your own Validator

For downcase validation

    class DowncaseValidator < Csv2hash::ExtraValidator
        def valid? value
            !!(value.match /^[a-z]+$/)
        end
    end

in your rule

    cell position: [0,0], key: 'name', extra_validator: DowncaseValidator.new,
        message: 'your data should be written in lowercase only.'

Csv data

    [ [ 'Foo' ] ]

Changes

please refere to CHANGELOG.md doc

Upgrading

please refere to UPGRADE.md doc

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Added some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request