From 8fbccf4fc597b8cabe1cc7d4326e12ea4998dbd8 Mon Sep 17 00:00:00 2001
From: Jaime Soriano Pastor <jsoriano@elastic.co>
Date: Thu, 12 Mar 2026 17:36:57 +0100
Subject: [PATCH] Keep the parsed pattern property keys

---
 schema.go     | 4 ++--
 subSchema.go  | 1 +
 validation.go | 5 ++---
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/schema.go b/schema.go
index 5a2599e9..05e7ddf3 100644
--- a/schema.go
+++ b/schema.go
@@ -321,14 +321,14 @@ func (d *Schema) parseSchema(documentNode interface{}, currentSchema *subSchema)
 			if len(patternPropertiesMap) > 0 {
 				currentSchema.patternProperties = make(map[string]*subSchema)
 				for k, v := range patternPropertiesMap {
-					_, err := regexp.MatchString(k, "")
+					re, err := regexp.Compile(k)
 					if err != nil {
 						return errors.New(formatErrorDescription(
 							Locale.RegexPattern(),
 							ErrorDetails{"pattern": k},
 						))
 					}
-					newSchema := &subSchema{property: k, parent: currentSchema, ref: currentSchema.ref}
+					newSchema := &subSchema{property: k, parent: currentSchema, ref: currentSchema.ref, patternPropertyKey: re}
 					err = d.parseSchema(v, newSchema)
 					if err != nil {
 						return errors.New(err.Error())
diff --git a/subSchema.go b/subSchema.go
index ec779812..51ea42bd 100644
--- a/subSchema.go
+++ b/subSchema.go
@@ -124,6 +124,7 @@ type subSchema struct {
 	dependencies         map[string]interface{}
 	additionalProperties interface{}
 	patternProperties    map[string]*subSchema
+	patternPropertyKey   *regexp.Regexp
 	propertyNames        *subSchema
 
 	// validation : array
diff --git a/validation.go b/validation.go
index 9081bd92..0c9c3e66 100644
--- a/validation.go
+++ b/validation.go
@@ -29,7 +29,6 @@ import (
 	"encoding/json"
 	"math/big"
 	"reflect"
-	"regexp"
 	"strconv"
 	"strings"
 	"unicode/utf8"
@@ -687,8 +686,8 @@ func (v *subSchema) validatePatternProperty(currentSubSchema *subSchema, key str
 
 	validated := false
 
-	for pk, pv := range currentSubSchema.patternProperties {
-		if matches, _ := regexp.MatchString(pk, key); matches {
+	for _, pv := range currentSubSchema.patternProperties {
+		if pv.patternPropertyKey != nil && pv.patternPropertyKey.MatchString(key) {
 			validated = true
 			subContext := NewJsonContext(key, context)
 			validationResult := pv.subValidateWithContext(value, subContext)