from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/items/")
async def read_items(q: Union[str, None] = None):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

#### Docker Compose

Você pode estar implantando em um **único servidor** (não em um cluster) com o **Docker Compose**, então você não teria uma maneira fácil de gerenciar a replicação de contêineres (com o Docker Compose) enquanto preserva a rede compartilhada e o **balanceamento de carga**.

from typing import Union

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(q: Union[str, None] = Query(default=None, alias="item-query")):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

from typing import Annotated, Union

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Annotated[Union[str, None], Query(min_length=3, max_length=50)] = None,
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

from typing import Annotated, Union

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Annotated[Union[str, None], Query(title="Query string", min_length=3)] = None,
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

```

////

#### `Union` বা `Optional` ব্যবহার

যদি আপনি Python 3.10-এর নীচের সংস্করণ ব্যবহার করেন, তবে এখানে আমার খুবই **ব্যক্তিগত** দৃষ্টিভঙ্গি থেকে একটি টিপস:

* 🚨 `Optional[SomeType]` ব্যবহার এড়িয়ে চলুন।
* এর পরিবর্তে ✨ **`Union[SomeType, None]` ব্যবহার করুন** ✨।

from typing import Optional, Union

from dirty_equals import IsDict
from fastapi import FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: Optional[str] = None


class OtherItem(BaseModel):
    price: int


@app.post("/items/")
def save_union_body(item: Union[OtherItem, Item]):
    return {"item": item}

from typing import Annotated, Union

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Annotated[
        Union[str, None],
        Query(
            title="Query string",
            description="Query string for the items to search in the database that have a good match",
            min_length=3,
        ),
    ] = None,
):

		setCopy[k] = v
	}
	return setCopy
}

// add - adds TargetID to the set.
func (set TargetIDSet) add(targetID TargetID) {
	set[targetID] = struct{}{}
}

// Union - returns union with given set as new set.
func (set TargetIDSet) Union(sset TargetIDSet) TargetIDSet {
	nset := set.Clone()

	for k := range sset {
		nset.add(k)
	}

	return nset
}

from typing import Annotated, Union

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Annotated[
        Union[str, None],
        Query(
            alias="item-query",
            title="Query string",
            description="Query string for the items to search in the database that have a good match",
            min_length=3,
            max_length=50,