#62.TIL | FastAPI 공식문서 따라하기(5)

https://slender-danger-059.notion.site/6-Query-Parameters-and-String-Validations-0a4928924fa6419c8eb970a13ded3c01

Query Parameters and String Validations

FastAPI에서 파라미터에 대한 추가적인 검증을 지원한다.

기존에 사용하던 파라미터 검증

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})
    return results

추가적인 validation

Import Query

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, max_length=50)):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})
    return results

Use Query as the default value

• Query를 default값 넣는 곳에 넣고, 다양한 validation 옵션 등을 줄 수 있다.

• max_length

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, max_length=50)):**
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})
    return results

• min_length

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, min_length=3, max_length=50)**
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})
    return results

• regular expression (정규표현식)
  • ^: starts with the following characters, doesn't have characters before.
  • fixedquery: has the exact value fixedquery.
  • $: ends there, doesn't have any more characters after fixedquery.

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, min_length=3, max_length=50, regex="^fixedquery$"**
    )
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})
    return results

• default values

from fastapi import FastAPI, Query

app = FastAPI()

@app.get("/items/")
**async def read_items(q: str = Query(default="fixedquery", min_length=3)):**
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})
    return results

• required
  • 1) default value를 선언하지 않기

    from fastapi import FastAPI, Query
    
    app = FastAPI()
    
    @app.get("/items/")
    **async def read_items(q: str = Query(min_length=3)):**
        results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
        if q:
            results.update({"q": q})
        return results

  • 2) Ellipsis (…)

    from fastapi import FastAPI, Query
    
    app = FastAPI()
    
    @app.get("/items/")
    **async def read_items(q: str = Query(default=..., min_length=3)):**
        results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
        if q:
            results.update({"q": q})
        return results

  • 3) default를 required 선언

    from fastapi import FastAPI, Query
    **from pydantic import Required**
    
    app = FastAPI()
    
    @app.get("/items/")
    **async def read_items(q: str = Query(default=Required, min_length=3)):**
        results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
        if q:
            results.update({"q": q})
        return results

추가) 더 많은 meta data 추가하기

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,
        **title="Query string",**
        **description="Query string for the items to search in the database that have a good match",**
        min_length=3,
    )
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})
    return results