Error in Example 6-1: Non-existent Params class

[ModarYaghi]

While working through "FastAPI: Modern Python Web Development," I discovered an error in Example 6-1 on page [page number]. The example imports and uses a Params class that doesn't exist in the FastAPI framework:

`
from fastapi import FastAPI, Depends, Params # Error: Params doesn't exist
app = FastAPI()

-# the dependency function:
def user_dep(name: str = Params, password: str = Params): # Error: Invalid usage
return {"name": name, "valid": True}

-# the path function / web endpoint:
@app.get("/user")
def get_user(user: dict = Depends(user_dep)) -> dict:
return user
`

FastAPI doesn't have a Params class. For required parameters in a dependency function, we should either:

[allseenn]

My investigation revealed several important points in Example 6-1:

1. In this Example, the superclass is named in the plural form but should be singular: Param
2. The superclass is not imported in the package root, so you cannot do a simple import like:

from fastapi import Param

3. However, you could import Param directly from its module:

from fastapi.params import Param

4. Since Query and other subclasses extend Param, the following code will work correctly:

from fastapi import FastAPI, Depends, Query

app = FastAPI()

def user_dep(name: str = Query, password: str = Query):
    return {"name": name, "valid": True}

@app.get("/user")

def get_user(user: dict = Depends(user_dep)) -> dict:
    return user