From c666f03041683de03f6acf0cd25b5d771fb87d5a Mon Sep 17 00:00:00 2001
From: timonrieger <mail@timonrieger.de>
Date: Thu, 12 Feb 2026 00:03:23 +0100
Subject: [PATCH] import field_validator for UUID properties with patterns

---
 .../codegen/languages/AbstractPythonCodegen.java   |  4 ++++
 .../codegen/python/PythonClientCodegenTest.java    | 10 ++++++++++
 .../resources/bugs/issue_uuid_with_pattern.yaml    | 14 ++++++++++++++
 3 files changed, 28 insertions(+)
 create mode 100644 modules/openapi-generator/src/test/resources/bugs/issue_uuid_with_pattern.yaml

diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractPythonCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractPythonCodegen.java
index 0f43180be5a0..a4c775057c47 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractPythonCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractPythonCodegen.java
@@ -2064,6 +2064,10 @@ private PythonType fromCommon(IJsonSchemaValidationProperties cp) {
                 moduleImports.add("pydantic", "field_validator");
             }
 
+            if (cp.getPattern() != null) {
+                moduleImports.add("pydantic", "field_validator");
+            }
+
             if (cp.getIsArray()) {
                 return arrayType(cp);
             } else if (cp.getIsMap() || cp.getIsFreeFormObject()) {
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/python/PythonClientCodegenTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/python/PythonClientCodegenTest.java
index a18f2f40d11b..0ec48cfb7072 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/python/PythonClientCodegenTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/python/PythonClientCodegenTest.java
@@ -660,6 +660,16 @@ public void testPoetry1LicenseFormat() throws IOException {
         TestUtils.assertFileNotContains(pyprojectPath, "license = { text = \"Apache-2.0\" }");
     }
 
+    @Test(description = "UUID property with pattern should import field_validator")
+    public void testUuidWithPatternImportsFieldValidator() throws IOException {
+        final DefaultCodegen codegen = new PythonClientCodegen();
+        final String outputPath = generateFiles(codegen, "src/test/resources/bugs/issue_uuid_with_pattern.yaml");
+        final Path p = Paths.get(outputPath + "openapi_client/models/uuid_with_pattern.py");
+
+        assertFileExists(p);
+        assertFileContains(p, "from pydantic import BaseModel, ConfigDict, field_validator");
+    }
+
     @Test(description = "Verify non-poetry1 mode uses object notation for license")
     public void testNonPoetry1LicenseFormat() throws IOException {
         File output = Files.createTempDirectory("test").toFile().getCanonicalFile();
diff --git a/modules/openapi-generator/src/test/resources/bugs/issue_uuid_with_pattern.yaml b/modules/openapi-generator/src/test/resources/bugs/issue_uuid_with_pattern.yaml
new file mode 100644
index 000000000000..0ad4a72487b1
--- /dev/null
+++ b/modules/openapi-generator/src/test/resources/bugs/issue_uuid_with_pattern.yaml
@@ -0,0 +1,14 @@
+openapi: 3.0.0
+info:
+  title: Test UUID with pattern
+  version: 1.0.0
+paths: {}
+components:
+  schemas:
+    UuidWithPattern:
+      type: object
+      properties:
+        id:
+          type: string
+          format: uuid
+          pattern: "^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-4[0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}$"