* `$`: danach endet, keine weiteren Zeichen hat als `fixedquery`.

Wenn Sie sich verloren fühlen bei all diesen **„Regulärer Ausdruck“**-Konzepten, keine Sorge. Reguläre Ausdrücke sind für viele Menschen ein schwieriges Thema. Sie können auch ohne reguläre Ausdrücke eine ganze Menge machen.

Aber wenn Sie sie brauchen und sie lernen, wissen Sie, dass Sie sie bereits direkt in **FastAPI** verwenden können.

### Pydantic v1 `regex` statt `pattern`

{* ../../docs_src/background_tasks/tutorial002_an_py310.py hl[13,15,22,25] *}


In this example, the messages will be written to the `log.txt` file *after* the response is sent.

If there was a query in the request, it will be written to the log in a background task.

And then another background task generated at the *path operation function* will write a message using the `email` path parameter.

/*
 * Copyright 2022 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

    // 3) array has no space available
    //
    // In case 2 we shift the existing chars to the left, and in case 3 we create a bigger
    // array, then they both become case 1.

    if (availableCapacity(charBuffer) == 0) {
      if (charBuffer.position() > 0) {
        // (2) There is room in the buffer. Move existing bytes to the beginning.
        Java8Compatibility.flip(charBuffer.compact());
      } else {

    // 3) array has no space available
    //
    // In case 2 we shift the existing chars to the left, and in case 3 we create a bigger
    // array, then they both become case 1.

    if (availableCapacity(charBuffer) == 0) {
      if (charBuffer.position() > 0) {
        // (2) There is room in the buffer. Move existing bytes to the beginning.
        Java8Compatibility.flip(charBuffer.compact());
      } else {

  // API server instances report the version they can decode and the version they
  // encode objects to when persisting objects in the backend.
  optional StorageVersionStatus status = 3;
}

// Describes the state of the storageVersion at a certain point.
message StorageVersionCondition {
  // Type of the condition.
  // +required
  optional string type = 1;

  // Status of the condition, one of True, False, Unknown.

   *
   * <p>If a character has no mapped replacement then it is checked against the safe range. If it
   * lies outside that, then {@link #escapeUnsafe} is called, otherwise no escaping is performed.
   *
   * @param replacementMap a map of characters to their escaped representations
   * @param safeMin the lowest character value in the safe range
   * @param safeMax the highest character value in the safe range
   */

  // 1. If host is precise, the request matches this rule if the http host header is equal to Host.
  // 2. If host is a wildcard, then the request matches this rule if the http host header
  // is to equal to the suffix (removing the first label) of the wildcard rule.
  // +optional
  optional string host = 1;

  // IngressRuleValue represents a rule to route requests for this IngressRule.

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).

  /**
   * Merges a value into a part of the map by applying a remapping function.
   *
   * <p>If any parts of the range are already present in this map, those parts are mapped to new
   * values by applying the remapping function. The remapping function accepts the map's existing
   * value for that part of the range and the given value. It returns the value to be associated