I'm not from the core but in my experience the chances are better opening a PR with the feature, specially if the implementation is simple.
I can even review the code, I've made a few PRs before with the implementation of the ignored columns and I'm familiar with the code. On Thursday, August 29, 2019 at 2:29:15 PM UTC-3, Dan Ott wrote: > > ActiveRecord has the ActiveRecord::Base.ignored_columns = %w(some columns > to ignore) method to blocklist columns that ActiveRecord loads from the > database. Spelunking the ActiveRecord source, I found no corresponding > method that acts as an allowlist for columns that will be loaded.I found > myself reaching for an allowlist as I started to take advantage of Rails > 6's multi-database support. In my context, data from another database that > used to be wrapped in a REST endpoint can now be accessed directly. When > making this direct access, I want to ignore every attribute except the few > I am specifically interested in. Because we’re in a multiple-app > environment, we don’t necessarily have control over columns being added or > dropped from the secondary database during runtime. We don’t want our > application to go down because another team removed an experimental column > from their database.To solve this problem with ignored_columns, we had to > enumerate all the existing columns. > > class Dogs < AnimalsBase > self.ignored_columns = %w(some list of columns that can never be exhaustive > because new columns could be added all the time) > end > > This suffers from the problem of new columns could be added at any time. > The list of ignored columns has to be constantly tended to ensure we’re > robust against a runtime error of columns going away.What I wanted to > reach for was something like > > class Dogs < AnimalsBase > self.allowed_columns = %w(id and only the exact columns needed) > end > > With this approach, we’re robust against the other database adding and > removing columns. We still run the risk of encountering runtime errors if > one of our exactly-requested columns goes away. I can’t come up with a way > to mitigate that risk aside from improving communications between teams.I’m > not solid on the name allowed_columns but it was the first thing I > reached for.For the time being, I implemented this with a monkey patch to > load_schema! > > ActiveRecord::Base.concerning "AllowedColumns" do > included do > self.allowed_columns = [].freeze > end > > module ClassMethods > def allowed_columns > if defined?(@allowed_columns) > @allowed_columns > else > superclass.allowed_columns > end > end > > def allowed_columns=(columns) > @allowed_columns = columns.map(&:to_s) > end > > # copied from from > https://github.com/rails/rails/blob/2dea8c29c794bec564a2e69ad715d25024e93932/activerecord/lib/active_record/model_schema.rb#L484-L497 > def load_schema! > unless table_name > raise ActiveRecord::TableNotSpecified, "#{self} has no table > configured. Set one with #{self}.table_name=" > end > @columns_hash = > connection.schema_cache.columns_hash(table_name).except(*ignored_columns) > @columns_hash = @columns_hash.slice(*allowed_columns) if > allowed_columns.present? # This is the additional line > @columns_hash.each do |name, column| > define_attribute( > name, > connection.lookup_cast_type_from_column(column), > default: column.default, > user_provided_default: false > ) > end > end > end > end > > Is this a feature that others would find useful now that we’re working > with first-class multi-database support? > -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Core" group. To unsubscribe from this group and stop receiving emails from it, send an email to rubyonrails-core+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/rubyonrails-core/7f881ecd-88ea-4892-8ac1-d8c10a8e274b%40googlegroups.com.
