csvrecord - read in comma-separated values (csv) records with typed structs / schemas

Usage

beer.csv:

“rewery,City,Name,Abv Andechser Klosterbrauerei,Andechs,Doppelbock Dunkel,7% Augustiner Bräu München,München,Edelstoff,5.6% Bayerische Staatsbrauerei Weihenstephan,Freising,Hefe Weissbier,5.4% Brauerei Spezial,Bamberg,Rauchbier Märzen,5.1% Hacker-Pschorr Bräu,München,Münchner Dunkel,5.0% Staatliches Hofbräuhaus München,München,Hofbräu Oktoberfestbier,6.3%

“

Step 1: Define a (typed) struct for the comma-separated values (csv) records. Example:

“by require ‘csvrecord’

Beer = CsvRecord.define do field :brewery ## note: default type is :string field :city field :name field :abv, Float ## allows type specified as class (or use :float) end

“

or in “classic” style:

“by class Beer < CsvRecord::Base field :brewery field :city field :name field :abv, Float end

“

Step 2: Read in the comma-separated values (csv) datafile. Example:

“by beers = Beer.read( ‘beer.csv’ ).to_a

puts “#beersbeers.size beers:” pp beers

“

pretty prints (pp):

“ beers: [#, #, #, ]

“

Or loop over the records. Example:

“uby Beer.read( ‘beer.csv’ ).each do |rec| puts “#recrec.name (#recrec.abv%) by #recrec.brewery, #recrec.city” end

-or-

Beer.foreach( ‘beer.csv’ ) do |rec| puts “#recrec.name (#recrec.abv%) by #recrec.brewery, #recrec.city” end

“

printing:

“oppelbock Dunkel (7.0%) by Andechser Klosterbrauerei, Andechs Edelstoff (5.6%) by Augustiner Bräu München, München Hefe Weissbier (5.4%) by Bayerische Staatsbrauerei Weihenstephan, Freising Rauchbier Märzen (5.1%) by Brauerei Spezial, Bamberg Münchner Dunkel (5.0%) by Hacker-Pschorr Bräu, München Hofbräu Oktoberfestbier (6.3%) by Staatliches Hofbräuhaus München, München

“

Or create new records from scratch. Example:

“uby beer = Beer.new( ‘Andechser Klosterbrauerei’, ‘Andechs’, ‘Doppelbock Dunkel’, ‘7%’ )

-or-

values = [Andechser Klosterbrauerei, Andechs, Doppelbock Dunkel, 7%] beer = Beer.new( values )

-or-

beer = Beer.new( brewery: ‘Andechser Klosterbrauerei’, city: ‘Andechs’, name: ‘Doppelbock Dunkel’, abv: ‘7%’ )

-or-

hash = { brewery: ‘Andechser Klosterbrauerei’, city: ‘Andechs’, name: ‘Doppelbock Dunkel’, abv: ‘7%’ } beer = Beer.new( hash )

-or-

beer = Beer.new beer.update( brewery: ‘Andechser Klosterbrauerei’, city: ‘Andechs’, name: ‘Doppelbock Dunkel’ ) beer.update( abv: 7.0 )

-or-

beer = Beer.new beer.parse( [Andechser Klosterbrauerei, Andechs, Doppelbock Dunkel, 7%] )

-or-

beer = Beer.new beer.parse( ‘Andechser Klosterbrauerei,Andechs,Doppelbock Dunkel,7%’ )

-or-

beer = Beer.new beer.brewery = ‘Andechser Klosterbrauerei’ beer.name = ‘Doppelbock Dunkel’ beer.abv = 7.0

“

And so on. That’s it.

Frequently Asked Questions (FAQs) and Answers

Q: What about ActiveRecord models? Why not inherit from ActiveRecord::Base so you get the SQL relational database magic / machinery for “free”?

Good point. CsvRecord and ActiveRecord are different. ActiveRecord has its own database schema / attributes. Using CsvPack - the tabular data package you can, however, for your convenience auto-generate ActiveRecord model classes and ActiveRecord schema migrations (that is, tables and indices, etc.) from the tabular datapackage schema (in the JSON Schema format). That was kind of the start of the exercise :-), that is, the genesis for building CsvRecord in the first place.

To sum up - use CsvRecord for comma-separated values (csv) data imports or data “wrangling” and use ActiveRecord for SQL queries / analysis and more. In the good old unix tradition - the work together but have its own (limited / focused) purpose.

Alternatives

See the Libraries & Tools section in the Awesome CSV page.

License

The csvrecord scripts are dedicated to the public domain. Use it as you please with no restrictions whatsoever.

Questions? Comments?

Send them along to the wwwmake forum. Thanks!