在这里，我们在 Pydantic 的 `Settings` 类中创建了一个名为 `Config` 的类，并将 `env_file` 设置为我们想要使用的 dotenv 文件的文件名。

/// tip

`Config` 类仅用于 Pydantic 配置。您可以在<a href="https://docs.pydantic.dev/latest/api/config/" class="external-link" target="_blank">Pydantic Model Config</a>中阅读更多相关信息。

///

### 使用 `lru_cache` 仅创建一次 `Settings`

从磁盘中读取文件通常是一项耗时的（慢）操作，因此您可能希望仅在首次读取后并重复使用相同的设置对象，而不是为每个请求都读取它。

但是，每次执行以下操作：

```Python
Settings()
```

   * stripes, the intended concurrency level, and the typical number of keys used in a {@code
   * bulkGet(keys)} operation. See <a href="http://www.mathpages.com/home/kmath199.htm">Balls in
   * Bins model</a> for mathematical formulas that can be used to estimate the probability of
   * collisions.
   *
   * @param keys arbitrary non-null keys

```Python
from datetime import date

from pydantic import BaseModel

# Declare a variable as a str
# and get editor support inside the function
def main(user_id: str):
    return user_id


# A Pydantic model
class User(BaseModel):
    id: int
    name: str
    joined: date
```

これは以下のように用いられます:

```Python
my_user: User = User(id=3, name="John Doe", joined="2018-07-19")

second_user_data = {

Gewoon standaard **Python**.

Bijvoorbeeld, voor een `int`:

```Python
item_id: int
```

of voor een complexer `Item` model:

```Python
item: Item
```

...en met die ene verklaring krijg je:

* Editor ondersteuning, inclusief:
    * Code aanvulling.
    * Type validatie.
* Validatie van data:

 * string is not human readable, but can be used with classes like [InetAddress] to establish
 * connections.
 *
 * ## Why another URL model?
 *
 * Java includes both [java.net.URL][URL] and [java.net.URI][URI]. We offer a new URL
 * model to address problems that the others don't.
 *
 * ### Different URLs should be different
 *

import org.apache.maven.jline.MessageUtils;
import org.apache.maven.lifecycle.LifecycleExecutionException;
import org.apache.maven.logging.api.LogLevelRecorder;
import org.apache.maven.model.building.ModelProcessor;
import org.apache.maven.model.root.RootLocator;
import org.apache.maven.project.MavenProject;
import org.apache.maven.properties.internal.EnvironmentUtils;
import org.apache.maven.properties.internal.SystemProperties;

Just standard **Python**.

For example, for an `int`:

```Python
item_id: int
```

or for a more complex `Item` model:

```Python
item: Item
```

...and with that single declaration you get:

* Editor support, including:
    * Completion.
    * Type checks.
* Validation of data:

quarkus/integration-tests/jpa-mapping-xml/legacy-library-a/pom.xml
	quarkus/extensions/hibernate-orm/runtime/pom.xml
quarkus/independent-projects/bootstrap/gradle-resolver/pom.xml
	quarkus/independent-projects/bootstrap/app-model/pom.xml
quarkus/integration-tests/test-extension/extension/runtime/pom.xml
	quarkus/extensions/arc/runtime/pom.xml
	quarkus/extensions/undertow/runtime/pom.xml
	quarkus/extensions/jaxb/runtime/pom.xml

-2.0.txt Apache Maven https://maven.apache.org/ https://maven.apache.org/ Maven is a project development management and comprehension tool. Maven is a project development management and comprehension tool. Based on the concept of a project object model: builds, dependency management, documentation creation, site publication, and distribution publication are all controlled from the declarative file. Maven can be extended by plugins to utilise a number of other development tools for reporting or the...

    processed_keys = set()

    for field in fields_to_extract:
        alias = None
        if isinstance(received_params, Headers):
            # Handle fields extracted from a Pydantic Model for a header, each field
            # doesn't have a FieldInfo of type Header with the default convert_underscores=True
            convert_underscores = getattr(field.field_info, "convert_underscores", True)