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[BUG][PYTHON] JSON serialization fails for UUID fields in generated Python #22063
Description
I am using the maven plugin openapi-generator-maven-plugin (python generator), to generate Python code that includes UUID fields. Since 7.15 version of this plugin, the to_json method of the generated python object containing an UUID field leads to this error: Object of type UUID is not JSON serializable error
There is an example to reproduce the issue
components:
schemas:
MyObject:
type: object
properties:
id:
type: string
format: uuid
from my_api.model.my_object import MyObject
import uuid
obj = MyObject(id=uuid.uuid4())
json_str = obj.to_json()
Activity
EspenHa commentedon Oct 12, 2025
I was able to reproduce this issue. I found a workaround by using this instead:
obj.model_dump_json(by_alias=True, exclude_unset=True), based on this TODO in the current template:openapi-generator/modules/openapi-generator/src/main/resources/python/model_generic.mustache
Line 130 in 81a3488
It seems this TODO was planned for pydantic v2, so maybe it is time for a switch over to this method instead of the old method?
fa0311 commentedon Jul 20, 2026
This should be fixed since #23210 — to_json no longer goes through plain json.dumps. Just verified a uuid field on master and it serializes fine now. Please retest with the latest version.