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FastrAPI provides parameter classes for extracting and validating different types of request data. These classes follow the same pattern as FastAPI’s parameter classes.

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Overview

Query

Extract URL query parameters

Path

Extract path parameters

Body

Extract request body data

Header

Extract HTTP headers

Cookie

Extract cookies

Form

Extract form data

File

Extract file uploads

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Query

Extract and validate URL query parameters.

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Parameters

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default
any
default:"None"
Default value if parameter is not provided
​
alias
string
default:"None"
Alternative name for the parameter in the URL
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title
string
default:"None"
Title for API documentation
​
description
string
default:"None"
Description for API documentation
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gt
float
default:"None"
Greater than validation for numeric values
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ge
float
default:"None"
Greater than or equal validation for numeric values
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lt
float
default:"None"
Less than validation for numeric values
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le
float
default:"None"
Less than or equal validation for numeric values
​
min_length
int
default:"None"
Minimum length for string values
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max_length
int
default:"None"
Maximum length for string values
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pattern
string
default:"None"
Regex pattern for string validation
​
deprecated
bool
default:"None"
Mark parameter as deprecated in API documentation
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include_in_schema
bool
default:"true"
Whether to include in OpenAPI schema
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examples
any
default:"None"
Example values for API documentation

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Example

from fastrapi import FastrAPI, Query

app = FastrAPI()

@app.get("/items")
def get_items(
    skip: int = Query(0, ge=0, description="Number of items to skip"),
    limit: int = Query(10, ge=1, le=100, description="Number of items to return"),
    search: str = Query(None, min_length=1, max_length=50)
):
    return {"skip": skip, "limit": limit, "search": search}

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Path

Extract and validate path parameters from URL paths.

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Parameters

Path accepts the same parameters as Query (see above).

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Example

from fastrapi import FastrAPI, Path

app = FastrAPI()

@app.get("/items/{item_id}")
def get_item(
    item_id: int = Path(..., ge=1, description="The ID of the item")
):
    return {"item_id": item_id}

​
Body

Extract and validate request body data.

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Parameters

​
default
any
default:"None"
Default value if body is not provided
​
embed
bool
default:"False"
Whether to expect the body to be embedded under a key
​
media_type
string
default:"application/json"
Expected media type of the body
​
alias
string
default:"None"
Alternative name for the body parameter
​
title
string
default:"None"
Title for API documentation
​
description
string
default:"None"
Description for API documentation

​
Example

from fastrapi import FastrAPI, Body
from pydantic import BaseModel

app = FastrAPI()

class Item(BaseModel):
    name: str
    price: float

@app.post("/items")
def create_item(
    item: Item = Body(..., description="Item to create")
):
    return {"item": item}
Extract and validate HTTP headers.

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Parameters

Header accepts similar parameters to Query for validation.

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Example

from fastrapi import FastrAPI, Header

app = FastrAPI()

@app.get("/")
def read_items(
    user_agent: str = Header(None, description="Client user agent"),
    x_api_key: str = Header(..., alias="X-API-Key")
):
    return {"user_agent": user_agent, "api_key": x_api_key}
Extract and validate cookies.

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Parameters

Cookie accepts similar parameters to Query for validation.

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Example

from fastrapi import FastrAPI, Cookie

app = FastrAPI()

@app.get("/")
def read_cookies(
    session_id: str = Cookie(None, description="Session identifier")
):
    return {"session_id": session_id}

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Form

Extract form data from application/x-www-form-urlencoded or multipart/form-data requests.

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Parameters

Form accepts similar parameters to Query for validation.

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Example

from fastrapi import FastrAPI, Form

app = FastrAPI()

@app.post("/login")
def login(
    username: str = Form(..., description="Username"),
    password: str = Form(..., description="Password")
):
    return {"username": username}

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File

Extract file uploads from multipart form data.

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Parameters

​
default
any
default:"None"
Default value if file is not provided
​
description
string
default:"None"
Description for API documentation

​
Example

from fastrapi import FastrAPI, File, UploadFile

app = FastrAPI()

@app.post("/upload")
async def upload_file(
    file: UploadFile = File(..., description="File to upload")
):
    contents = await file.read()
    return {
        "filename": file.filename,
        "content_type": file.content_type,
        "size": len(contents)
    }

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Validation

All parameter classes support validation constraints:
  • Numeric validation: gt, ge, lt, le
  • String validation: min_length, max_length, pattern
  • Documentation: title, description, examples, deprecated
When validation fails, FastrAPI automatically returns a 422 Unprocessable Entity response with details about the validation errors.

Request handling

Understand request processing

Pydantic validation

Use Pydantic models for validation

UploadFile

Handle file uploads

Dependencies

Dependency injection system

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