How to maintain the datetime format same as input

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I have created a model as below.

class Inventory(BaseModel): locationId: str = Field(…, example=“LOC44242”, description=“Unique Store/Location identifier.”) inventoryDate: datetime = Field(…, example=“2019-04-01T00:00:00.000Z”, description=“ISO 8601 format”)

I am sending inventoryDate in 2019-04-01T00:00:00.000Z format I want FastAPI to maintain this format but it is changing it to 2019-05-01T11:53:21.988000+00:00

is there a way yo maintain the format?

Example

Here’s a self-contained, minimal, reproducible, example with my use case:

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}

Description

• Open the browser and call the endpoint /.
• It returns a JSON with {"Hello": "World"}.
• But I expected it to return {"Hello": "Sara"}.

Environment

• OS: [e.g. Linux / Windows / macOS]:
• FastAPI Version [e.g. 0.3.0]:

To know the FastAPI version use:

python -c "import fastapi; print(fastapi.__version__)"

• Python version:

To know the Python version use:

python --version

Additional context

[waynerv]

Here is a simple example using jsonable_encoder of FastAPI:

from datetime import datetime

from fastapi.encoders import jsonable_encoder
from pydantic import BaseModel, Field


class Inventory(BaseModel):
    locationId: str = Field(..., example="LOC44242", description="Unique Store/Location identifier.")
    inventoryDate: datetime = Field(..., example="2019-04-01T00:00:00.000Z", description="ISO 8601 format")


a = Inventory(locationId='LOC44242', inventoryDate='2019-04-01T11:53:21.980Z')

print(jsonable_encoder(a.dict(), custom_encoder={datetime: lambda dt: dt.isoformat().replace("+00:00", "Z")}))

Output:

{'locationId': 'LOC44242', 'inventoryDate': '2019-04-01T11:53:21.980000Z'}

[waynerv]

Actually The converting is executed by Pydantic, not by FastAPI.