Feature/bronto error demo

[adelevie]

WIP to demo the error when requiring bronto

[adelevie]

error emanates from lib/rails_nlp.rb:

  def self.suggest_stopwords(n: stopwords_default, n_max: stopwords_max)
    whitelist = RailsNlp.configuration.stopwords_whitelist || []
    blacklist = RailsNlp.configuration.stopwords_blacklist || []
    limit = [n, n_max].min
    freq = Wordcount.group(:keyword_id).order('count_all DESC').limit(limit).count
    # ^ this line ^
    Keyword.where(id: freq.map(&:first)).pluck(:name) - blacklist + whitelist
  end

pry-rescue tells us:

From: /Users/alandelevie/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.1/lib/active_record/relation/query_methods.rb @ line 997 ActiveRecord::QueryMethods#build_select:

     994: def build_select(arel, selects)
     995:   if !selects.empty?
     996:     expanded_select = selects.map do |field|
 =>  997:       columns_hash.key?(field.to_s) ? arel_table[field] : field
     998:     end
     999:     arel.project(*expanded_select)
    1000:   else
    1001:     arel.project(@klass.arel_table[Arel.star])
    1002:   end
    1003: end

repl'ing:

ArgumentError: wrong number of arguments (0 for 1)
from /Users/alandelevie/.rvm/gems/ruby-2.1.1/gems/sequel-3.48.0/lib/sequel/sql.rb:98:in `to_s'
[1] pry(#<RailsNlp::Wordcount::ActiveRecord_Relation>)> selects.first.to_s
=> "#<Arel::Nodes::Count:0x000001037d1ed8>"
[2] pry(#<RailsNlp::Wordcount::ActiveRecord_Relation>)> selects.second.to_s
ArgumentError: wrong number of arguments (0 for 1)
from /Users/alandelevie/.rvm/gems/ruby-2.1.1/gems/sequel-3.48.0/lib/sequel/sql.rb:98:in `to_s'
[3] pry(#<RailsNlp::Wordcount::ActiveRecord_Relation>)> selects.first.class
=> Arel::Nodes::Count
[4] pry(#<RailsNlp::Wordcount::ActiveRecord_Relation>)> selects.second.class
=> Sequel::SQL::AliasedExpression
[5] pry(#<RailsNlp::Wordcount::ActiveRecord_Relation>)> 

It appears that the pieces of the selects array, created inside of RailsNlp::suggest_stopwords (specifically freq = Wordcount.group(:keyword_id).order('count_all DESC').limit(limit).count), create an Arel::Nodes::Count and a Sequel::SQL::AliasedExpression without type-checking or noticing. ActiveRecord calls #to_s on the items in the selects array, but instances of Sequel::SQL::AliasedExpression have the weirdest #to_s definition:

# File lib/sequel_core/sql.rb, line 403
def to_s(ds)
  ds.aliased_expression_sql(self)
end

(source)

[adelevie]

looks like we're not the first: rails/arel#133