Class: HasHelpers::LimitFavorites

Inherits:
PsqlHq::Trigger
  • Object
show all
Defined in:
app/triggers/has_helpers/limit_favorites.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(klass:, limit:, **options) ⇒ LimitFavorites

Returns a new instance of LimitFavorites.



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# File 'app/triggers/has_helpers/limit_favorites.rb', line 7

def initialize(klass:, limit:, **options)
  @klass = klass
  @limit = limit
  super(options)
end

Instance Attribute Details

#klass ⇒ Object (readonly)

Returns the value of attribute klass.



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# File 'app/triggers/has_helpers/limit_favorites.rb', line 5

def klass
  @klass
end

#limit ⇒ Object (readonly)

Returns the value of attribute limit.



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# File 'app/triggers/has_helpers/limit_favorites.rb', line 5

def limit
  @limit
end

Class Method Details

.constraint_trigger? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'app/triggers/has_helpers/limit_favorites.rb', line 17

def self.constraint_trigger?
  true
end

.data_trigger? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'app/triggers/has_helpers/limit_favorites.rb', line 21

def self.data_trigger?
  false
end

.drop_by_function_name(function_name) ⇒ Object 



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# File 'app/triggers/has_helpers/limit_favorites.rb', line 89

def drop_by_function_name(function_name)
  ::ActiveRecord::Base.connection.execute <<-SQL
    DROP FUNCTION IF EXISTS \"#{function_name}\"() CASCADE;
  SQL
  puts "-- Dropped #{function_name} (if it existed) and any dependent triggers"
end

.prefix ⇒ Object 



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# File 'app/triggers/has_helpers/limit_favorites.rb', line 13

def self.prefix
  "FHQ"
end

.triggers ⇒ Object 



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# File 'app/triggers/has_helpers/limit_favorites.rb', line 85

def triggers
  @triggers ||= []
end

Instance Method Details

#create ⇒ Object 



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# File 'app/triggers/has_helpers/limit_favorites.rb', line 29

def create
  ::ActiveRecord::Base.connection.execute trigger_function

  ::ActiveRecord::Base.connection.execute <<-SQL
    CREATE CONSTRAINT TRIGGER "#{trigger_name}"
    AFTER INSERT OR UPDATE OF #{favorite_foreign_key} ON favorites DEFERRABLE INITIALLY DEFERRED
    FOR EACH ROW EXECUTE PROCEDURE "#{function_name}"();
  SQL

  puts "-- Created trigger #{trigger_name} and function #{function_name}."
end

#drop ⇒ Object 



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# File 'app/triggers/has_helpers/limit_favorites.rb', line 41

def drop
  LimitFavorites.drop_by_function_name(function_name)
end

#name ⇒ Object 



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# File 'app/triggers/has_helpers/limit_favorites.rb', line 25

def name
  "limit_favorites_#{klass.table_name}"
end

#trigger_function ⇒ Object 



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# File 'app/triggers/has_helpers/limit_favorites.rb', line 45

def trigger_function
  <<-SQL
    CREATE OR REPLACE FUNCTION public."#{function_name}"() RETURNS TRIGGER LANGUAGE plpgsql AS $function$
      DECLARE
        row_limit INTEGER;
        nrows INTEGER;
        resource_id TEXT;
      BEGIN
        #{exit_if_skipped_sql}

        row_limit := #{limit};

        SELECT
          COUNT(*) INTO nrows
        FROM favorites
        WHERE favorites.created_by_id = NEW.created_by_id
        AND #{favorite_foreign_key} IS NOT NULL;

        IF nrows > row_limit THEN
          SELECT
            format('%s-%s', '#{favorite_foreign_key.titleize}', NEW.#{favorite_foreign_key}::text)
          INTO resource_id;

          RAISE NOTICE 'favorite limit: resource_id = %', resource_id;
          RAISE 'Exceeded favorite limit of % for %', row_limit, resource_id;
        END IF;

        RETURN NULL;
      END
    $function$;
  SQL
end