Method Build

tools/search/filter.go:632–667

Build converts the expression into a SQL fragment. Implements [dbx.Expression] interface.

(db *dbx.DB, params dbx.Params)

//
// Implements [dbx.Expression] interface.
func (e *manyVsManyExpr) Build(db *dbx.DB, params dbx.Params) string {
	if e.left.MultiMatchSubQuery == nil || e.right.MultiMatchSubQuery == nil {
		return "0=1"
	}

	lAlias := "__ml" + security.PseudorandomString(8)
	rAlias := "__mr" + security.PseudorandomString(8)

	whereExpr, buildErr := buildResolversExpr(
		&ResolverResult{
			NullFallback: e.left.NullFallback,
			Identifier:   "[[" + lAlias + ".multiMatchValue]]",
		},
		e.op,
		&ResolverResult{
			NullFallback: e.right.NullFallback,
			Identifier:   "[[" + rAlias + ".multiMatchValue]]",
			// note: the AfterBuild needs to be handled only once and it
			// doesn't matter whether it is applied on the left or right subquery operand
			AfterBuild: dbx.Not, // inverse for the not-exist expression
		},
	)

	if buildErr != nil {
		return "0=1"
	}

	return fmt.Sprintf(
		"NOT EXISTS (SELECT 1 FROM (%s) {{%s}} LEFT JOIN (%s) {{%s}} WHERE %s)",
		e.left.MultiMatchSubQuery.Build(db, params),
		lAlias,
		e.right.MultiMatchSubQuery.Build(db, params),
		rAlias,
		whereExpr.Build(db, params),
	)
}

// -------------------------------------------------------------------