{* ../../docs_src/dependencies/tutorial007_py39.py hl[3,5] *}

## Sub-dependencies with `yield` { #sub-dependencies-with-yield }

You can have sub-dependencies and "trees" of sub-dependencies of any size and shape, and any or all of them can use `yield`.

**FastAPI** will make sure that the "exit code" in each dependency with `yield` is run in the correct order.

{* ../../docs_src/security/tutorial005_an_py310.py hl[106,108:116] *}

## Verificar el `username` y la forma de los datos { #verify-the-username-and-data-shape }

Verificamos que obtenemos un `username`, y extraemos los scopes.

{* ../../docs_src/security/tutorial005_an_py310.py hl[106,108:116] *}

## Den `username` und das Format der Daten überprüfen { #verify-the-username-and-data-shape }

Wir verifizieren, dass wir einen `username` erhalten, und extrahieren die Scopes.

For example, if you declare a parameter of type `Hero`, it will be read from the **JSON body**.

The same way, you can declare it as the function's **return type**, and then the shape of the data will show up in the automatic API docs UI.

{* ../../docs_src/sql_databases/tutorial001_an_py310.py ln[40:45] hl[40:45] *}

## Pydantic models { #pydantic-models }

<a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic</a> is a Python library to perform data validation.

You declare the "shape" of the data as classes with attributes.

And each attribute has a type.

                or is_scalar_sequence_field(field)
                or (
                    lenient_issubclass(field.type_, BaseModel)
                    # For Pydantic v1
                    and getattr(field, "shape", 1) == 1
                )
            )

    return ParamDetails(type_annotation=type_annotation, depends=depends, field=field)


def add_param_to_fields(*, field: ModelField, dependant: Dependant) -> None:

 *  smb://host/share/a/b/c/d/
 * </code></td>
 * </tr>
 *
 * <tr>
 * <td ><code>
 *  smb://host/share/foo/bar/
 * </code></td>
 * <td ><code>
 *  /share2/zig/zag
 * </code></td>
 * <td><code>
 *  smb://host/share2/zig/zag
 * </code></td>
 * </tr>
 *
 * <tr>
 * <td ><code>
 *  smb://host/share/foo/bar/
 * </code></td>
 * <td ><code>
 *  ../zip/
 * </code></td>

the room.  The cook threw a frying-pan after her as she went out,
but it just missed her.

  Alice caught the baby with some difficulty, as it was a queer-
shaped little creature, and held out its arms and legs in all
directions, `just like a star-fish,' thought Alice.  The poor
little thing was snorting like a steam-engine when she caught it,

 *  c/d/
 * </code></td><td><code>
 *  smb1://host/share/a/b/c/d/
 * </code></td></tr>
 *
 * <tr><td ><code>
 *  smb1://host/share/foo/bar/
 * </code></td><td ><code>
 *  /share2/zig/zag
 * </code></td><td><code>
 *  smb1://host/share2/zig/zag
 * </code></td></tr>
 *
 * <tr><td ><code>
 *  smb1://host/share/foo/bar/
 * </code></td><td ><code>
 *  ../zip/
 * </code></td><td><code>

2CCF          ; valid                                  # 4.1  COPTIC SMALL LETTER OLD COPTIC HA
2CD0          ; mapped                 ; 2CD1          # 4.1  COPTIC CAPITAL LETTER L-SHAPED HA
2CD1          ; valid                                  # 4.1  COPTIC SMALL LETTER L-SHAPED HA
2CD2          ; mapped                 ; 2CD3          # 4.1  COPTIC CAPITAL LETTER OLD COPTIC HEI