class ConceptQL::Operators::TrimDateEnd

Trims the end_date of the LHS set of results by the RHS's earliest start_date (per person) If a the RHS contains a start_date that comes before the LHS's start_date that LHS result is completely discarded.

If there is no RHS result for an LHS result, the LHS result is passed thru unaffected.

If the RHS result's start_date is later than the LHS end_date, the LHS result is passed thru unaffected.

Public Instance Methods

query(db) click to toggle source
# File lib/conceptql/operators/trim_date_end.rb, line 33
def query(db)
  grouped_right = db.from(right_stream(db)).select_group(:person_id).select_append(Sequel.as(Sequel.function(:min, :start_date), :start_date))

  where_criteria = Sequel.expr { l__start_date <= r__start_date }
  where_criteria = where_criteria.|(r__start_date: nil)

  # If the RHS's min start date is less than the LHS start date,
  # the entire LHS date range is truncated, which implies the row itself
  # is ineligible to pass thru
  ds = db.from(left_stream(db))
            .left_join(Sequel.as(grouped_right, :r), l__person_id: :r__person_id)
            .where(where_criteria)
            .select(*new_columns)
            .select_append(Sequel.as(Sequel.function(:least, :l__end_date, :r__start_date), :end_date))

  ds = add_option_conditions(ds)
  ds.from_self
end
within_column() click to toggle source
# File lib/conceptql/operators/trim_date_end.rb, line 52
def within_column
  :l__end_date
end

Private Instance Methods

new_columns() click to toggle source
# File lib/conceptql/operators/trim_date_end.rb, line 57
def new_columns
  (dynamic_columns - [:end_date]).map { |col| "l__#{col}".to_sym }
end