Csv2Hash

(Travis CI)

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

Summary

Csv2Hash
Summary
- Installation
- Usage
  - Invoke parser
  - Parser options
  - Definition DSL
  - Definition Rules
  - Default rules values
  - Define where your data are expected
- Samples
  - Autodiscover generale setting
  - [MAPPING] Validation of cells with defined precision
  - Auto discover position feature in Mapping
  - [COLLECTION] Validation of a collection (Regular CSV)
  - Auto discover position feature in Collection
  - Structure validation rules
  - CSV Headers
  - Parser and configuration
  - Response
- Configuration
- Exception or Not !
  - On BREAK_ON_FAILURE MODE
  - On CSV MODE
  - Errors Format
    - Sample
      - Csv data
      - Rule
      - Error
- Personal Validator Rule
Yaml Config file
- YamlLoader
Type conversion
Changes
Upgrading
Yard doc
Contributing

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

Invoke parser

Csv2hash::Main.new(:<definition_name>, file_path_or_data, options).parse

Csv2hash::Main.new(:<definition_name>, options) do
  file_path_or_data
end.parse

Parser options

List of options :

ignore_blank_line: :boolean # i think is pretty straightforward to understand
sanitizer: :boolean remove trailing space, example:

  '  it is   a really  good idea!!   '

become

  => "it is a really good idea!!"

Definition DSL

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

Definition 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]

By default values are case sensitive but if you want the value to be a string that can be either 'yes' or 'no' case insentive ('Yes', 'YES', 'No', 'NO') you can define the following validation rule:

cell name: 'aswering', values: ['yes', 'no'], case_sensitive_values: false, 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 rules values

Only position is required:

:position

All remaining keys are optionals:

message: 'undefined :key on :position'
mappable: true
type: 'string'
values: nil
case_sensitive_values: true # When you define set of 'values'
nested: nil
allow_blank: false
extra_validator: nil

Define where your data are 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

Autodiscover generale setting

You can define your matching expression as exact match and case sensitive or not.

conf.ignore_case    = true # /Sex/ become /Sex/i
conf.exact_matching = true # /Sex/ become /\A(Sex)\z/

Both option can be cumulated : /Sex/ can become /\A(Sex)\z/i

For further information please see section Configuration

[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(:<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

Auto discover position feature in Mapping

This is a special feature for finding the Y index of row where you data start. For instance you have this following data :

|---------------|---------------|------|-----|
| Nickname      | jo            |      |     |
| First Name    | John          |      |     |
| Last Name     | Doe           |      |     |
|               |               |      |     |
| Employment    | CEO           |      |     |
| Post          | Doe           |      |     |
|               |               |      |     |
|               | Personal info | Age  | 26  |
|               | Sex           | Male |     |
|               |               |      |     |

You want extract Employment information and Personal info but we do not know if extra information will not come and break our index. This feature can be useful is this case.

You must change Y position (rows) by the column index and regex, the parser will search on this column the index row of this regex, here our rule :

cell position: [4,1], key: 'employment'

became

cell position: [[0, /Employment/],1], key: 'employment'

cell position: [[0, 'Employment'],1], key: 'employment'

[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(:<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

Auto discover position feature in Collection

This is a special feature for finding a specific column index on header. For example you have the following data:

| Name          | Age           |
|---------------|---------------|
| John Doe      | 23            |  
| Jane Doe      | 28            |
|               |               |
|               |               |

You want to extract Name and Age for all rows but you want the order of the columns to be able to change. You change the position to the regex of column index you are looking for. So this how the position

cell position: 0, key: 'name'

can be change to

cell position: /Name/ key: 'name'

cell position: 'Name' key: 'name'

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(:<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

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

Configuration

You can add a configuration file on your Rails project under this directory

add file config/initializers/csv2hash.rb

You can use the Rails generator for this

rails generate csh2hash:install

Csv2hash.configure do |conf|
  # Conversion of values
  # conf.convert        = false # default: false
  # conf.true_values    = ['yes','y','t'] # default: ['yes','y','t']
  # conf.false_values   = ['no','n','f']  # default: ['no','n','f']
  # conf.nil_values     = ['nil','null']  # default: ['nil','null']

  # Auto discover for (mapping and collection)
  # conf.ignore_case    = false # default: false
  # conf.exact_matching = false # default: false
end

For explanation of "Conversion of values" please take a look on Type conversion

For explanation of "Auto discover for (mapping and collection)" please take a look on Autodiscover generale setting

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' ] ]

Yaml Config file

You can defined rules into a yaml file

name: 'example'
mapping: 'mapping'
header_size: 2
structure_rules: { max_columns: 20 }
rules:
  - { position: [1,1], key: 'first_name' }
  - { position: [2,1], key: 'first_name' }

or for complex and verbose rule

name: 'example'
mapping: 'mapping'
header_size: 2
structure_rules: { max_columns: 20 }
rules:
  - !rule
    position: [1,1]
    key: 'first_name'
  - !rule
    position: [2,1]
    key: 'last_name'

Special attention, if you use ExtraValidator you must give only the String name of the classe, like that :

extra_validator: DowncaseValidator.new

should become

extra_validator: 'DowncaseValidator'

for autodiscover field you must give String without Regex like that :

position: [[0,/LastName/],1]

should become

position: [[0,'LastName'],1]

this change is due to Yaml conversion

You can write ERB file, should be named with following convention <file name>.yml.erb

YamlLoader

You can load your definition with YamlLoader llike that :

loader = Csv2hash::YamlLoader.load!('config/rules.yml.erb')
loader.definition

loader = Csv2hash::YamlLoader.new('config/rules.yml.erb')
loader.load!
loader.definition

Type conversion

By default Csv2hash doesn't convert basic value, but you can activate this option convert = true

You can define which String are converted on true, false or nil

true_values = ['yes','y','t']

With this configuration 'Yes' become => true (Basic boolean ruby value)

conf.false_values = ['no','n','f']

With this configuration 'No' become => false (Basic boolean ruby value)

conf.nil_values = ['nil','null']

With this configuration 'Null' become => nil (Basic ruby value)

For further information please see section Configuration

Changes

please refere to CHANGELOG.md doc

Upgrading

please refere to UPGRADE.md doc

Yard doc

bundle exec yard --plugin tomdoc

Contributing

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

csv2hash

Development

Runtime

Csv2Hash

Summary

Installation

Usage

Invoke parser

Parser options

Definition DSL

Definition Rules

Default rules values

Define where your data are expected

Samples

Autodiscover generale setting

[MAPPING] Validation of cells with defined precision

Auto discover position feature in Mapping

[COLLECTION] Validation of a collection (Regular CSV)

Auto discover position feature in Collection

Structure validation rules

CSV Headers

Parser and configuration

Response

Configuration

Exception or Not !

On BREAK_ON_FAILURE MODE

On CSV MODE

Errors Format

Sample

Csv data

Rule

Error

Personal Validator Rule

Yaml Config file

YamlLoader

Type conversion

Changes

Upgrading

Yard doc

Contributing