假设你有一个带有默认值的 Pydantic 模型，例如：

{* ../../docs_src/separate_openapi_schemas/tutorial001_py310.py ln[1:7] hl[7] *}

### 输入用的模型 { #model-for-input }

如果你像下面这样把该模型用作输入：

{* ../../docs_src/separate_openapi_schemas/tutorial001_py310.py ln[1:15] hl[14] *}

...那么 `description` 字段将**不是必填项**，因为它的默认值是 `None`。

### 文档中的输入模型 { #input-model-in-docs }

你可以在文档中确认，`description` 字段没有**红色星号**，也就是未被标记为必填：

<div class="screenshot">

    public ClassRealm createProjectRealm(Model model, List<Artifact> artifacts) {
        Objects.requireNonNull(model, "model cannot be null");

        ClassLoader parent = getMavenApiRealm();

        return createRealm(getKey(model), RealmType.Project, parent, null, null, artifacts);
    }

    private static String getKey(Model model) {

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

import java.io.File;
import java.util.Date;
import java.util.List;
import java.util.Properties;

import org.apache.maven.model.Model;
import org.apache.maven.model.Profile;
import org.apache.maven.model.resolution.ModelResolver;
import org.apache.maven.model.resolution.WorkspaceModelResolver;

/**

        Mockito.verify(context.logger)
                .info(
                        "  -a, --all             Apply all upgrades (equivalent to --model-version 4.1.0 --infer --model --plugins)");
    }

    @Test
    void testHelpIncludesDefaultBehavior() throws Exception {
        UpgradeContext context = createMockContext();

        help.execute(context);

#include "tensorflow/c/eager/unified_api_testutil.h"

namespace tensorflow {
namespace gradients {

/* Returns numerical grad inside `dtheta_approx` given `forward` model and
 * parameter specified by `input_index`.
 *
 * I.e. if y = <output of the forward model> and w = inputs[input_index],
 * this will calculate dy/dw numerically.
 *
 * `use_function` indicates whether to use graph mode(true) or eager(false).
 *

	if db5.Error != nil {
		t.Errorf("Should not raise error for join where identical fields in different tables. Error: %s", db5.Error.Error())
	}

          <basedir>${project.basedir}/../../api/maven-api-settings</basedir>
          <velocityBasedir>${project.basedir}/../../src/mdo</velocityBasedir>
          <models>
            <model>src/main/mdo/settings.mdo</model>
          </models>
          <params>
            <param>forcedIOModelVersion=1.2.0</param>
            <param>packageModelV3=org.apache.maven.settings</param>

from fastapi import FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()


class MyModel(BaseModel):
    """
    A model with a form feed character in the title.
    \f
    Text after form feed character.
    """


@app.get("/foo")
def foo(v: MyModel):  # pragma: no cover
    pass


client = TestClient(app)


def test_openapi():

    public ClassDocBuilder(DslDocModel model, JavadocConverter javadocConverter) {
        commentBuilder = new ClassDocCommentBuilder(javadocConverter, listener);
        propertiesBuilder = new ClassDocPropertiesBuilder(javadocConverter, listener);
        methodsBuilder = new ClassDocMethodsBuilder(javadocConverter, listener);
        extensionsBuilder = new ClassDocExtensionsBuilder(model, listener);

	return execG[T]{g: &g[T]{
		db: c.db,
		ops: append(c.ops, func(db *DB) *DB {
			var r T
			return db.Model(r).Raw(sql, values...)
		}),
	}}
}

func (c *g[T]) Exec(ctx context.Context, sql string, values ...interface{}) error {
	var r T
	return c.apply(ctx).Model(r).Exec(sql, values...).Error
}

type createG[T any] struct {
	chainG[T]
}