## Use Case { #use-case }

Let's start with an example **use case** and then see how to solve it with this.

Let's imagine that you have some **machine learning models** that you want to use to handle requests. 🤖

The same models are shared among requests, so, it's not one model per request, or one per user or something similar.

Remarquez que cela signifie « `one_person` est une **instance** de la classe `Person` ».

Cela ne signifie pas « `one_person` est la **classe** appelée `Person` ».

## Modèles Pydantic { #pydantic-models }

[Pydantic](https://docs.pydantic.dev/) est une bibliothèque Python pour effectuer de la validation de données.

Vous déclarez la « forme » de la donnée sous forme de classes avec des attributs.

* Documentation automatique des modèles de données avec [**JSON Schema**](https://json-schema.org/) (puisque OpenAPI est lui-même basé sur JSON Schema).
* Conçu autour de ces standards, après une étude méticuleuse. Plutôt qu'une couche ajoutée après coup.

from enum import Enum

from fastapi import FastAPI


class ModelName(str, Enum):
    alexnet = "alexnet"
    resnet = "resnet"
    lenet = "lenet"


app = FastAPI()


@app.get("/models/{model_name}")
async def get_model(model_name: ModelName):
    if model_name is ModelName.alexnet:
        return {"model_name": model_name, "message": "Deep Learning FTW!"}

    if model_name.value == "lenet":

    page.get_by_role("button", name="Try it out").click()
    page.get_by_role("heading", name="Servers").click()
    # Manually add the screenshot
    page.screenshot(path="docs/en/docs/img/tutorial/query-param-models/image01.png")

    # ---------------------
    context.close()
    browser.close()


process = subprocess.Popen(
    ["fastapi", "run", "docs_src/query_param_models/tutorial001.py"]
)
try:

            </goals>
            <configuration>
              <version>4.0.0</version>
              <models>
                <model>target/mdo/maven.mdo</model>
              </models>
              <templates>
                <template>src/main/mdo/model-v3.vm</template>
                <template>src/main/mdo/merger.vm</template>
                <template>src/main/mdo/transformer.vm</template>

 * under the License.
 */
package org.apache.maven.model.building;

import java.util.EnumSet;
import java.util.List;
import java.util.Set;

import org.apache.maven.model.Model;
import org.apache.maven.model.io.ModelParseException;

/**
 * Collects problems that are encountered during model building. The primary purpose of this component is to account for

    *   `Model.fit_generator`, `Model.evaluate_generator`,
        `Model.predict_generator`, `Model.train_on_batch`,
        `Model.test_on_batch`, and `Model.predict_on_batch` methods now respect
        the `run_eagerly` property, and will correctly run using `tf.function`
        by default. Note that `Model.fit_generator`, `Model.evaluate_generator`,

Here are several ways to do it.

## Extra JSON Schema data in Pydantic models { #extra-json-schema-data-in-pydantic-models }

You can declare `examples` for a Pydantic model that will be added to the generated JSON Schema.

{* ../../docs_src/schema_extra_example/tutorial001_py310.py hl[13:24] *}

That extra info will be added as-is to the output **JSON Schema** for that model, and it will be used in the API docs.

Aynı şekilde bu veritabanı bir Pydantic model'i (attribute'lara sahip bir obje) de kabul etmez; yalnızca bir `dict` kabul eder.

Bunun için `jsonable_encoder` kullanabilirsiniz.

Bir Pydantic model gibi bir obje alır ve JSON ile uyumlu bir versiyonunu döndürür:

{* ../../docs_src/encoder/tutorial001_py310.py hl[4,21] *}

Bu örnekte, Pydantic model'i bir `dict`'e, `datetime`'ı da bir `str`'e dönüştürür.