CODEWITHSUNDEEP
ruby-on-railsarrayspostgresqlmigration
anonn023432
anonn023432

Reputation: 3120

Convert existing rails column from string to array

I've an existing rails application and one of column's has existing semi-colon separated string. I want to convert the same into an array with an empty array as default.

Also, for rows which already have data in the semi-colon separated string format we need it to get converted into a proper array.

Upvotes: 1

Views: 2305

Answers (3)

Ghaith.d
Ghaith.d

Reputation: 11

The best way to do it efficiently, is by using PSQL query directly as follows:

class ChangeQualificationToArray < ActiveRecord::Migration
  def change
    execute <<-SQL
      ALTER TABLE "coaches" ALTER COLUMN "qualifications" TYPE text[] USING string_to_array("coaches"."qualifications", ',')::text[];
    SQL
  end
end

Upvotes: 1

Michael Koper
Michael Koper

Reputation: 9771

I solved it like this:

class ChangeQualificationToArray < ActiveRecord::Migration

  def change
    change_column :coaches, :qualifications, "varchar[] USING (string_to_array(qualifications, ';'))"
  end

end

Upvotes: 1

anonn023432
anonn023432

Reputation: 3120

The above is a pretty common scenario in development of any application and a lot of people face problems while doing the same in Rails.

In my opinion the easiest way to get all this done is:

  1. Generate a new migration : rails g migration changeSomethingToArray

  2. In the new migration file, add the following code.

    class ChangeQualificationToArray < ActiveRecord::Migration
def change
  rename_column :coaches, :qualifications, :qualifications_text
  add_column :coaches, :qualifications, :text, default: []

  coaches = Coach.all
  coaches.each do |c|
    c.qualifications = convert_to_array(c.qualifications_text)
    c.save
  end

  remove_column :coaches, :qualifications_text

end

private

def convert_to_array(string)
  string.split(';')  
  # This can be changed to `,` or  whatever you're using to split your string.
end
end

Upvotes: 0

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