CODEWITHSUNDEEP
ruby-on-railsdatabaseactiverecordscriptingschema
agentofuser
agentofuser

Reputation: 9307

Reload column names in ActiveRecord model class

I have a script using ActiveRecord that creates column names dynamically based on values read from a CSV file, something like this:

FasterCSV.foreach('votes.csv', :headers => true) do |row|
  column_name = "roll_call_id_#{row['roll_call_id']}"

  if !Legislator.columns.map(&:name).include?(column_name)
    connection_pool.connection.add_column('legislators', column_name, 'string')
  end
end

The problem is that, after creating the new column, I can't do a legislator.update_attribute(column_name, value) because the class doesn't pick up the new column and complains it doesn't exist.

How can I make it query the table structure again?

Upvotes: 15

Views: 6228

Answers (2)

user6085070
user6085070

Reputation: 1

as obvio171 pointed out, it's quite easy:

You need to create a bare model class upfront.

Then in the migration you need to call MyModel.reset_column_information, so that the column information is reloaded so that is up with the new table you just created (or changed)

You can then use just every method to create new records.

I use something like:

data = [[1,'foo'], [2,'bar'],[3,'zip']].map{|a,b| {id:a, txt:b} }
MyModel.create!(data)

But if your seed data is more than a few constants, then you should probably not burry your data into a migration like this.

Upvotes: 0

agentofuser
agentofuser

Reputation: 9307

Legislator.reset_column_information (API info)

Upvotes: 38

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