Class: ConceptQL::Operators::Count

Inherits:
PassThru show all
Defined in:
lib/conceptql/operators/count.rb

Instance Attribute Summary

Attributes inherited from Operator

#arguments, #errors, #nodifier, #options, #upstreams, #values

Instance Method Summary collapse

Methods inherited from PassThru

#domains

Methods inherited from Operator

#annotate, #cast_column, #code_list, codes_should_match, #columns, #create_upstreams, #data_model, #database_type, default_query_columns, #domains, #dup_values, #dynamic_columns, #evaluate, inherited, #initialize, #inspect, #label, new, #operator_name, #optimized, query_columns, register, require_column, #required_columns, #scope, #select_it, #setup_select, #sql, #stream, #to_op, #unionable?, #upstreams_valid?, #valid?

Methods included from Metadatable

#allows_many_upstreams, #allows_one_upstream, #argument, #auto_label, #basic_type, #category, #derive_metadata_from_validations, #desc, #domains, #get_desc, #humanized_class_name, #inherited, #just_class_name, #no_desc, #option, #predominant_domains, #pref_name, #preferred_name, #reset_categories, #standard_description, #to_metadata, #validate_at_least_one_upstream_to_metadata, #validate_at_most_one_upstream_to_metadata, #validate_no_arguments_to_metadata, #validate_no_upstreams_to_metadata, #validate_one_upstream_to_metadata, #validate_required_options_to_metadata, #warn_about_missing_metadata

Constructor Details

This class inherits a constructor from ConceptQL::Operators::Operator

Instance Method Details

#query(db) ⇒ Object 



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# File 'lib/conceptql/operators/count.rb', line 18

def query(db)
  db.from(unioned(db))
    .select_group(*(query_cols - [:value_as_number]))
    .select_append{count(1).as(:value_as_number)}
    .from_self
end

#query_cols ⇒ Object 



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# File 'lib/conceptql/operators/count.rb', line 14

def query_cols
  dynamic_columns - [:value_as_number] + [:value_as_number]
end

#unioned(db) ⇒ Object 



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# File 'lib/conceptql/operators/count.rb', line 25

def unioned(db)
  upstreams.map { |c| c.evaluate(db) }.inject do |uni, q|
    uni.union(q)
  end
end