Method Modifier

dialect/sql/sqlgraph/graph.go:592–622

Modifier returns a modifier function that limits the number of rows of the eager load query.

(partitionBy string, limit int, orderBy ...sql.Querier)

// Modifier returns a modifier function that limits the number of rows of the eager load query.
func (l *NeighborsLimit) Modifier(partitionBy string, limit int, orderBy ...sql.Querier) func(s *sql.Selector) {
	return func(s *sql.Selector) {
		var (
			d  = sql.Dialect(s.Dialect())
			rn = sql.RowNumber().PartitionBy(partitionBy)
		)
		switch {
		case len(orderBy) > 0:
			rn.OrderExpr(orderBy...)
		case l.DefaultOrderField != "":
			rn.OrderBy(l.DefaultOrderField)
		default:
			s.AddError(errors.New("no order terms provided for window function"))
			return
		}
		s.SetDistinct(false)
		with := d.With(l.SrcCTE).
			As(s.Clone()).
			With(l.LimitCTE).
			As(
				d.Select("*").
					AppendSelectExprAs(rn, l.RowNumber).
					From(d.Table(l.SrcCTE)),
			)
		t := d.Table(l.LimitCTE).As(s.TableName())
		*s = *d.Select(s.UnqualifiedColumns()...).
			From(t).
			Where(sql.LTE(t.C(l.RowNumber), limit)).
			Prefix(with)
	}
}

type (
	// FieldSpec holds the information for updating a field