<!--
    Some tests need reflective access to the internals of these packages. It is only the
    tests themselves and not the code being tested that needs that access, though there's no
    obvious way to ensure that.

    We could consider arranging things so that only the tests we know need this would get
    the add-opens. Right now that doesn't seem worth the effort, though.
    -->
    <test.add.opens>

    <!--
    Some tests need reflective access to the internals of these packages. It is only the
    tests themselves and not the code being tested that needs that access, though there's no
    obvious way to ensure that.

    We could consider arranging things so that only the tests we know need this would get
    the add-opens. Right now that doesn't seem worth the effort, though.
    -->
    <test.add.opens>

                    final Smb2WriteResponse resp = th.send(request, RequestParam.NO_RETRY);
                    cnt = resp.getCount();
                } else {
                    final SmbComWriteAndX request =
                            new SmbComWriteAndX(th.getConfig(), fh.getFid(), this.fp, len - w - off, b, off, w, null);
                    th.send(request, this.write_andx_resp, RequestParam.NO_RETRY);

# Handling Errors { #handling-errors }

There are many situations in which you need to notify an error to a client that is using your API.

This client could be a browser with a frontend, a code from someone else, an IoT device, etc.

You could need to tell the client that:

* The client doesn't have enough privileges for that operation.
* The client doesn't have access to that resource.
* The item the client was trying to access doesn't exist.
* etc.

     * Reads a byte of data from this input stream.
     *
     * @throws IOException
     *             if a network error occurs
     */

    @Override
    public int read() throws IOException {
        // need oplocks to cache otherwise use BufferedInputStream
        if (read(this.tmp, 0, 1) == -1) {
            return -1;
        }
        return this.tmp[0] & 0xFF;
    }

    /**

    /**
     * Reads a byte of data from this input stream.
     *
     * @throws IOException if a network error occurs
     */

    @Override
    public int read() throws IOException {
        // need oplocks to cache otherwise use BufferedInputStream
        if (read(tmp, 0, 1) == -1) {
            return -1;
        }
        return tmp[0] & 0xFF;
    }

    /**

            } catch (final IOException ioe) {
                this.state = 0;
                throw ioe;
            }
        }
    }

    /**
     * Send and receive a DCE/RPC message
     *
     * @param msg
     *            the message to send
     * @throws DcerpcException
     *            if there is a DCE/RPC protocol error
     * @throws IOException

```

...without adding the required parameter `needy`, you will see an error like:

```JSON
{
  "detail": [
    {
      "type": "missing",
      "loc": [
        "query",
        "needy"
      ],
      "msg": "Field required",
      "input": null
    }
  ]
}
```

As `needy` is a required parameter, you would need to set it in the URL:

```

     *
     * Operations larger than this size will use RDMA read/write
     * instead of send/receive.
     *
     * @return threshold in bytes
     */
    int getRdmaReadWriteThreshold();

    /**
     * Get maximum RDMA send size
     *
     * @return max send size in bytes
     */
    int getRdmaMaxSendSize();

    /**
     * Get maximum RDMA receive size
     *

# Body - Multiple Parameters { #body-multiple-parameters }

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.