need DATETIME_FORMAT to ninja Schema

[LeonemZhang]

I hope to add a global configuration to modify the format of the datetime return

[LeonemZhang]

django-ninja>=1.4.1,
django==5.2,
pydantic==2.11.3,

from pydantic import Field

class DatetimeSchema(Schema):
    create_time: datetime = Field(
        default=datetime.now(),
        examples=[datetime.now()],
    )
    update_time: datetime = Field(
        default=datetime.now(),
        examples=[datetime.now()],
    )

    @staticmethod
    def resolve_create_time(obj):
        return str(obj.create_time.strftime("%Y-%m-%d %H:%M:%S"))

    @staticmethod
    def resolve_update_time(obj):
        return str(obj.update_time.strftime("%Y-%m-%d %H:%M:%S"))

class CustomSchema(DatetimeSchema):
    ...

json result
        "create_time": "2025-04-18T02:57:03",
        "update_time": "2025-04-18T02:57:03",

[LeonemZhang]

from ninja import Schema

class DatetimeSchema(Schema):
    class Config(Schema.Config):
        json_encoders = {
            datetime: lambda dt: dt.strftime("%Y-%m-%d %H:%M:%S")
        }


class CustomSchema(DatetimeSchema):
    ...

json result
   "create_time": "2025-04-18T02:57:03.313Z",
   "update_time": "2025-04-18T02:57:03.313Z"

[LeonemZhang]

from pydantic import BaseModel

class DatetimeSchema(BaseModel):
    class Config:
        json_encoders = {
            datetime: lambda dt: dt.strftime("%Y-%m-%d %H:%M:%S")
        }

error:

ERROR:root:1 validation error for NinjaResponseSchema
response.items.0
  Input should be a valid dictionary or instance of FileDetailResp [type=model_type, input_value=<SysFile: 测试数据.pdf>, input_type=SysFile]
    For further information visit https://errors.pydantic.dev/2.11/v/model_type

[vitalik]

@LeonemZhang you can apply global json encoder for all dates/datetimes like this:

from ninja.renderers import JSONRenderer
from ninja.responses import NinjaJSONEncoder


class JsonEncoder(NinjaJSONEncoder):

    def default(self, o):
        if isinstance(o, datetime):
            return o.strftime('%Y-%m-%dT%H:%M:%S')
        return super().default(o)


class CustomJsonRender(JsonRenderer):
    encoder_class = JsonEncoder

...

api = NinjaAPI(renderer=CustomJsonRender())

[LeonemZhang]

Thanks, it works
but I can't find BaseJsonRenderer, I use from ninja.renderers import JSONRenderer instead
Perhaps we can update this configuration method in the documentation?

[vitalik]

@LeonemZhang yes - JSONRenderer is the one!