filter enhancements

resolvers/multi_match_subquery.go

@@ -0,0 +1,70 @@
+package resolvers
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/pocketbase/dbx"
+)
+
+var _ dbx.Expression = (*multiMatchSubquery)(nil)
+
+// join defines the specification for a single SQL JOIN clause.
+type join struct {
+	tableName  string
+	tableAlias string
+	on         dbx.Expression
+}
+
+// multiMatchSubquery defines a record multi-match subquery expression.
+type multiMatchSubquery struct {
+	baseTableAlias  string
+	fromTableName   string
+	fromTableAlias  string
+	valueIdentifier string
+	joins           []*join
+	params          dbx.Params
+}
+
+// Build converts the expression into a SQL fragment.
+//
+// Implements [dbx.Expression] interface.
+func (m *multiMatchSubquery) Build(db *dbx.DB, params dbx.Params) string {
+	if m.baseTableAlias == "" || m.fromTableName == "" || m.fromTableAlias == "" {
+		return "0=1"
+	}
+
+	if params == nil {
+		params = m.params
+	} else {
+		// merge by updating the parent params
+		for k, v := range m.params {
+			params[k] = v
+		}
+	}
+
+	var mergedJoins strings.Builder
+	for i, j := range m.joins {
+		if i > 0 {
+			mergedJoins.WriteString(" ")
+		}
+		mergedJoins.WriteString("LEFT JOIN ")
+		mergedJoins.WriteString(db.QuoteTableName(j.tableName))
+		mergedJoins.WriteString(" ")
+		mergedJoins.WriteString(db.QuoteTableName(j.tableAlias))
+		if j.on != nil {
+			mergedJoins.WriteString(" ON ")
+			mergedJoins.WriteString(j.on.Build(db, params))
+		}
+	}
+
+	return fmt.Sprintf(
+		`SELECT %s as [[multiMatchValue]] FROM %s %s %s WHERE %s = %s`,
+		db.QuoteColumnName(m.valueIdentifier),
+		db.QuoteTableName(m.fromTableName),
+		db.QuoteTableName(m.fromTableAlias),
+		mergedJoins.String(),
+		db.QuoteColumnName(m.fromTableAlias+".id"),
+		db.QuoteColumnName(m.baseTableAlias+".id"),
+	)
+}