var i = cursor.start
      val end = cursor.end
      if (buffer != null) {
        while (i < end) {
          keyIndex %= keyLength // Reassign to prevent overflow breaking counter.

          // Byte xor is experimental in Kotlin so we coerce bytes to int, xor them
          // and convert back to byte.
          val bufferInt: Int = buffer[i].toInt()
          val keyInt: Int = key[keyIndex].toInt()

# Learn { #learn }

Here are the introductory sections and the tutorials to learn **FastAPI**.

    owner_ids: list[int] | None = None


@app.get("/items/valid", response_model=Item)
def get_valid():
    return Item(aliased_name="valid", price=1.0)


@app.get("/items/coerce", response_model=Item)
def get_coerce():
    return Item(aliased_name="coerce", price="1.0")


@app.get("/items/validlist", response_model=list[Item])
def get_validlist():
    return [
        Item(aliased_name="foo"),

    owner_ids: list[int] | None = None


@app.get("/items/valid", response_model=Item)
def get_valid():
    return {"name": "valid", "price": 1.0}


@app.get("/items/coerce", response_model=Item)
def get_coerce():
    return {"name": "coerce", "price": "1.0"}


@app.get("/items/validlist", response_model=list[Item])
def get_validlist():
    return [
        {"name": "foo"},
        {"name": "bar", "price": 1.0},

{* ../../docs_src/security/tutorial004_an_py310.py hl[8,49,51,58:59,62:63,72:79] *}

Lorsque `authenticate_user` est appelée avec un nom d'utilisateur qui n'existe pas dans la base de données, nous exécutons tout de même `verify_password` contre un hachage factice.

Now that we have seen how to use `Path` and `Query`, let's see more advanced uses of request body declarations.

## Mix `Path`, `Query` and body parameters { #mix-path-query-and-body-parameters }

First, of course, you can mix `Path`, `Query` and request body parameter declarations freely and **FastAPI** will know what to do.

And you can also declare body parameters as optional, by setting the default to `None`:

          @ParametricNullness E key,
          List<? extends E> list,
          int foundIndex) {
        // Of course, we have to use binary search to find the precise
        // breakpoint...
        int lower = 0;
        int upper = foundIndex;
        // Of course, we have to use binary search to find the precise breakpoint...
        // Everything between lower and upper inclusive compares at <= 0.

@app.get("/items/object", response_model=Item)
def get_object():
    return Item(
        name="object", date=datetime(2021, 7, 26), price=1.0, owner_ids=[1, 2, 3]
    )


@app.get("/items/coerce", response_model=Item)
def get_coerce():
    return {"name": "coerce", "date": datetime(2021, 7, 26).isoformat(), "price": "1.0"}


@app.get("/items/validlist", response_model=list[Item])
def get_validlist():
    return [

{* ../../docs_src/json_base64_bytes/tutorial001_py310.py ln[1:2,12:16,29,38:41] hl[16] *}

## Pydantic `bytes` for Input and Output Data { #pydantic-bytes-for-input-and-output-data }

And of course, you can use the same model configured to use base64 to handle both input (*validate*) with `val_json_bytes` and output (*serialize*) with `ser_json_bytes` when receiving and sending JSON data.

    counter.write(data, 0, 5);
    written += 5;
    assertEquals(written, out.size());
    assertEquals(written, counter.getCount());

    counter.write(data, 2, 5);
    written += 5;
    assertEquals(written, out.size());
    assertEquals(written, counter.getCount());

    // Test that illegal arguments do not affect count