///

## Advanced User Guide { #advanced-user-guide }

There is also an **Advanced User Guide** that you can read later after this **Tutorial - User guide**.

The **Advanced User Guide** builds on this one, uses the same concepts, and teaches you some extra features.

But you should first read the **Tutorial - User Guide** (what you are reading right now).

In some cases, you may want to override the logic used by the `Request` and `APIRoute` classes.

In particular, this may be a good alternative to logic in a middleware.

For example, if you want to read or manipulate the request body before it is processed by your application.

/// danger

This is an "advanced" feature.

If you are just starting with **FastAPI** you might want to skip this section.

///

    """
    An HTTP exception you can raise in your own code to show errors to the client.

    This is for client errors, invalid authentication, invalid data, etc. Not for server
    errors in your code.

    Read more about it in the
    [FastAPI docs for Handling Errors](https://fastapi.tiangolo.com/tutorial/handling-errors/).

    ## Example

    ```python
    from fastapi import FastAPI, HTTPException

				return nil, err
			}
			continue
		}
		data, _ = json.Marshal(cfg)
		break
	}
	if osIsPermission(err) {
		logger.Info("Older config found but is not readable %s, proceeding to read config from other places", err)
	}
	if osIsNotExist(err) || osIsPermission(err) || len(data) == 0 {
		data, err = readConfig(GlobalContext, objAPI, configFile)
		if err != nil {

// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package cmd

import (
	"bufio"
	"bytes"
	"fmt"
	"io"
	"strings"
	"testing"
)

// Test read chunk line.
func TestReadChunkLine(t *testing.T) {
	type testCase struct {
		reader         *bufio.Reader
		expectedErr    error
		chunkSize      []byte
		chunkSignature []byte
	}
	// List of readers used.

        "info": {
            "title": "FastAPI",
            "version": "0.1.0",
        },
        "paths": {
            "/items/": {
                "get": {
                    "summary": "Read Items",
                    "operationId": "read_items_items__get",
                    "responses": {
                        "200": {
                            "description": "Successful Response",

# This ensures that previous jobs for the PR are canceled when the PR is
# updated.
concurrency:
  group: ${{ github.workflow }}-${{ github.head_ref }}
  cancel-in-progress: true

permissions:
  contents: read

jobs:
  build:
    name: Build Tests with Go ${{ matrix.go-version }} on ${{ matrix.os }}
    runs-on: ${{ matrix.os }}
    strategy:
      matrix:
        go-version: [1.24.x]
        os: [ubuntu-latest]

# This ensures that previous jobs for the PR are canceled when the PR is
# updated.
concurrency:
  group: ${{ github.workflow }}-${{ github.head_ref }}
  cancel-in-progress: true

permissions:
  contents: read

jobs:
  build:
    name: Go ${{ matrix.go-version }} on ${{ matrix.os }}
    runs-on: ${{ matrix.os }}
    strategy:
      matrix:
        go-version: [1.24.x]
        os: [ubuntu-latest]
    steps:

                    "description": "Production environment",
                },
            ],
            "paths": {
                "/app": {
                    "get": {
                        "summary": "Read Main",
                        "operationId": "read_main_app_get",
                        "responses": {
                            "200": {
                                "description": "Successful Response",

	isReadLock := false
	return dm.lockBlocking(ctx, cancel, id, source, isReadLock, opts)
}

// RLock holds a read lock on dm.
//
// If one or more read locks are already in use, it will grant another lock.
// Otherwise the calling go routine blocks until the mutex is available.
func (dm *DRWMutex) RLock(id, source string) {
	isReadLock := true