Query Parameters

Query parameters are the key-value pairs after ? in a URL. JustAPI extracts them automatically from function parameters.

from justapi import JustAPIApp

app = JustAPIApp()

@app.get("/items/")
def list_items(skip: int = 0, limit: int = 10):
    return {"skip": skip, "limit": limit}

• /items/ returns {"skip": 0, "limit": 10}
• /items/?skip=20&limit=50 returns {"skip": 20, "limit": 50}

Any parameter that has a default value is treated as a query parameter.

A query parameter is required if it has no default value:

@app.get("/search")
def search(q: str):  # required — no default value
    return {"query": q}

/search without ?q=... returns a validation error.

A query parameter is optional if it has a default value:

@app.get("/search")
def search(q: str = None):  # optional — defaults to None
    return {"query": q}

/search without ?q=... works and returns {"query": null}.

@app.get("/products")
def list_products(
    category: str = "all",
    min_price: float = 0.0,
    max_price: float = 1000.0,
    sort: str = "name",
    order: str = "asc",
):
    return {
        "category": category,
        "price_range": [min_price, max_price],
        "sort": sort,
        "order": order,
    }

All parameters are optional with their defaults. Clients only need to override the ones they care about.

JustAPI converts query parameters from strings to the declared Python type:

@app.get("/items/{item_id}")
def get_item(item_id: int, verbose: bool = False):
    return {"item_id": item_id, "verbose": verbose}

• /items/5?verbose=true — verbose is True
• /items/5?verbose=1 — verbose is True
• /items/5?verbose=false — verbose is False

Query parameters can repeat:

@app.get("/filter")
def filter_items(tags: list[str] = None):
    return {"tags": tags}

/filter?tags=a&tags=b&tags=c returns {"tags": ["a", "b", "c"]}.

• Parameters with default values are query parameters.
• Parameters without default values are required.
• JustAPI converts types automatically (str to int, "true" to True, etc.).
• Use list[T] for repeating query parameters.

• Query Parameters & String Validations — add min_length, max_length, pattern constraints
• Path Parameters — URL path parameters
• Request Body — JSON request bodies