From 47f20ce70f41249518b3a26f9e99e3f9a917a23b Mon Sep 17 00:00:00 2001
From: Daniele Esposti <daniele@withplum.com>
Date: Wed, 28 Aug 2024 20:43:22 +0200
Subject: [PATCH] Fixed generating Marshmallow DateTime formats

---
 src/apispec/ext/marshmallow/field_converter.py | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/src/apispec/ext/marshmallow/field_converter.py b/src/apispec/ext/marshmallow/field_converter.py
index 4e17aa2e..3bd16ed7 100644
--- a/src/apispec/ext/marshmallow/field_converter.py
+++ b/src/apispec/ext/marshmallow/field_converter.py
@@ -574,13 +574,25 @@ def datetime2properties(self, field, **kwargs: typing.Any) -> dict:
                     "example": "1676451277514.654",
                     "min": "0",
                 }
+            elif field.format is not None:
+                ret = {
+                    "type": "string",
+                    "format": None,
+                    "pattern": (
+                        field.metadata["pattern"]
+                        if field.metadata.get("pattern")
+                        else None
+                    ),
+                }
             else:
                 ret = {
                     "type": "string",
                     "format": None,
-                    "pattern": field.metadata["pattern"]
-                    if field.metadata.get("pattern")
-                    else None,
+                    "pattern": (
+                        field.metadata["pattern"]
+                        if field.metadata.get("pattern")
+                        else None
+                    ),
                 }
         return ret