* Documentation automatique des modèles de données avec <a href="http://json-schema.org/" class="external-link" target="_blank"><strong>JSON Schema</strong></a> (comme OpenAPI est aussi basée sur JSON Schema).
* Conçue avec ces standards après une analyse méticuleuse. Plutôt qu'en rajoutant des surcouches après coup.

#### Überprüfen Sie die `openapi.json`

Falls Sie wissen möchten, wie das rohe OpenAPI-Schema aussieht: FastAPI generiert automatisch ein JSON (Schema) mit den Beschreibungen Ihrer gesamten API.

* Automatic data model documentation with <a href="https://json-schema.org/" class="external-link" target="_blank"><strong>JSON Schema</strong></a> (as OpenAPI itself is based on JSON Schema).
* Designed around these standards, after a meticulous study. Instead of an afterthought layer on top.

## 创建 Pydantic 模型

现在让我们查看一下文件`sql_app/schemas.py`。

/// tip

为了避免 SQLAlchemy*模型*和 Pydantic*模型*之间的混淆，我们将有`models.py`（SQLAlchemy 模型的文件）和`schemas.py`（ Pydantic 模型的文件）。

这些 Pydantic 模型或多或少地定义了一个“schema”（一个有效的数据形状）。

因此，这将帮助我们在使用两者时避免混淆。

///

### 创建初始 Pydantic*模型*/模式

创建一个`ItemBase`和`UserBase`Pydantic*模型*（或者我们说“schema”），他们拥有创建或读取数据时具有的共同属性。

### API Docs

If you go to the API docs, you will see that it has the **schemas** for the data to be sent in requests and received in responses:

<img src="/img/tutorial/generate-clients/image01.png">

You can see those schemas because they were declared with the models in the app.

That information is available in the app's **OpenAPI schema**, and then shown in the API docs (by Swagger UI).

                        security_schemes
                    )
                if path_definitions:
                    definitions.update(path_definitions)
    if definitions:
        components["schemas"] = {k: definitions[k] for k in sorted(definitions)}
    if components:
        output["components"] = components
    output["paths"] = paths
    if webhook_paths:
        output["webhooks"] = webhook_paths

     */
    public static Schema newW3cXmlSchema(final Source schema) {
        assertArgumentNotNull("schema", schema);
        return newSchema(SchemaFactoryUtil.newW3cXmlSchemaFactory(), schema);
    }

    /**
     * URLからW3C XML Schemaのための{@link Schema}を生成します。
     *
     * @param schema
     *            W3C XML SchemaのURL。{@literal null}であってはいけません
     * @return {@link Schema}
     */

	}

	if schema.err == nil {
		schema.setRelation(relation)
		switch relation.Type {
		case HasOne:
			schema.Relationships.HasOne = append(schema.Relationships.HasOne, relation)
		case HasMany:
			schema.Relationships.HasMany = append(schema.Relationships.HasMany, relation)
		case BelongsTo:
			schema.Relationships.BelongsTo = append(schema.Relationships.BelongsTo, relation)
		case Many2Many:

			for _, rel := range dep.Schema.Relationships.Relations {
				if rel.Field.IgnoreMigration {
					continue
				}
				if c := rel.ParseConstraint(); c != nil && c.Schema == dep.Statement.Schema && c.Schema != c.ReferenceSchema {
					dep.Depends = append(dep.Depends, c.ReferenceSchema)
				}

				if rel.Type == schema.HasOne || rel.Type == schema.HasMany {
					beDependedOn[rel.FieldSchema] = true
				}

	"gorm.io/gorm/clause"
	"gorm.io/gorm/schema"
	"gorm.io/gorm/utils"
)

// BeforeCreate before create hooks
func BeforeCreate(db *gorm.DB) {
	if db.Error == nil && db.Statement.Schema != nil && !db.Statement.SkipHooks && (db.Statement.Schema.BeforeSave || db.Statement.Schema.BeforeCreate) {
		callMethod(db, func(value interface{}, tx *gorm.DB) (called bool) {
			if db.Statement.Schema.BeforeSave {