Read a table into an array in Ruby on Rails

Question

Using RoR 4, and SQlite3 for development, mySQL for production.

Given a table "Things":

POSITION    NAME     VALUE     CODE
1           Animal   Dog       1
1           Animal   Cat       2
1           Animal   Bird      3
2           Place    USA       1
2           Place    Other     2
3           Color    Red       a
3           Color    Blue      b
3           Color    Orange    c
4           Age      Young     a
4           Age      Middle    b
4           Age      Old       c
5           Alive    Yes       y
5           Alive    No        n

How can I read the table into an array that looks like this:

a = [["1", "Animal", "Dog", "1"],
     ["1", "Animal", "Cat", "2"],
     ["1", "Animal", "Bird", "3"],
     ["2", "Place", "USA", "1"],
     ["2", "Place", "Other", "2"],
     ["3", "Color", "Red", "a"],
     ["3", "Color", "Blue", "b"],
     ["3", "Color", "Orange", "c"],
     ["4", "Age", "Young", "a"],
     ["4", "Age", "Middle", "b"],
     ["4", "Age", "Old", "c"],
     ["5", "Alive", "Yes", "y"],
     ["5", "Alive", "No", "n"]]

Alejandro Babio · Accepted Answer · 2015-03-25 02:32:33Z

2

Just:

my_array = MyModel.select(:position, :name, :value, :code).map {|e| e.attributes.values}

I think it does the trick.

Edited

If you want all the fields:

my_array = MyModel.all.map {|e| e.attributes.values}

If you want each row to be a Hash:

my_array = MyModel.all.to_a

edited Mar 25, 2015 at 2:32

answered Mar 25, 2015 at 2:27

Alejandro Babio

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1 Comment

sabrams Over a year ago

Perfect! Is there a way to allow for undetermined columns? For example if I added an additional column at a later time, could this code simply pull all columns without hard coding each one?

pangpang · Accepted Answer · 2015-03-25 02:33:16Z

0

You can have a try.

ActiveRecord::Base.connection.execute('select * from table').map{ |row| row }

edited Mar 25, 2015 at 2:33

answered Mar 25, 2015 at 2:25

pangpang

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