Function HasNeighbors

dialect/sql/sqlgraph/graph.go:240–277

HasNeighbors applies on the given Selector a neighbors check.

(q *sql.Selector, s *Step)

// HasNeighbors applies on the given Selector a neighbors check.
func HasNeighbors(q *sql.Selector, s *Step) {
	builder := sql.Dialect(q.Dialect())
	switch {
	case s.ThroughEdgeTable():
		pk1 := s.Edge.Columns[0]
		if s.Edge.Inverse {
			pk1 = s.Edge.Columns[1]
		}
		join := builder.Table(s.Edge.Table).Schema(s.Edge.Schema)
		q.Where(
			sql.In(
				q.C(s.From.Column),
				builder.Select(join.C(pk1)).From(join),
			),
		)
	case s.FromEdgeOwner():
		q.Where(sql.NotNull(q.C(s.Edge.Columns[0])))
	case s.ToEdgeOwner():
		to := builder.Table(s.Edge.Table).Schema(s.Edge.Schema)
		// In case the edge reside on the same table, give
		// the edge an alias to make qualifier different.
		if s.From.Table == s.Edge.Table {
			to.As(fmt.Sprintf("%s_edge", s.Edge.Table))
		}
		q.Where(
			sql.Exists(
				builder.Select(to.C(s.Edge.Columns[0])).
					From(to).
					Where(
						sql.ColumnsEQ(
							q.C(s.From.Column),
							to.C(s.Edge.Columns[0]),
						),
					),
			),
		)
	}
}

// HasNeighborsWith applies on the given Selector a neighbors check.
// The given predicate applies its filtering on the selector.