书接上文，多个关联模型这种情况很常见。

特别是用户模型，因为：

* **输入模型**应该含密码
* **输出模型**不应含密码
* **数据库模型**可能需要包含哈希后的密码

/// danger | 危险

不要存储用户的明文密码。始终只存储之后可用于校验的“安全哈希”。

如果你还不了解，可以在[安全性章节](security/simple-oauth2.md#password-hashing)中学习什么是“密码哈希”。

///

## 多个模型 { #multiple-models }

下面的代码展示了不同模型处理密码字段的方式，及使用位置的大致思路：

{* ../../docs_src/extra_models/tutorial001_py310.py hl[7,9,14,20,22,27:28,31:33,38:39] *}

    @Test
    public void test_constructor_withMessageCodeMessageAndCause() {
        // Setup
        final String message = "Invalid query syntax error";
        final Exception cause = new RuntimeException("Query parsing failed");
        final VaMessenger<FessMessages> messageCode = messages -> messages.addErrorsInvalidQueryUnknown(UserMessages.GLOBAL_PROPERTY_KEY);

        // Execute

    /**
     * Creates a Type-2 message using the given raw Type-2 material.
     *
     * @param material The raw Type-2 material used to construct this message.
     * @throws IOException If an error occurs while parsing the material.
     */
    public Type2Message(final byte[] material) throws IOException {
        parse(material);
    }

    /**
     * Returns the challenge for this message.
     *

		case mrfMetaVersion:
		default:
			return re, fmt.Errorf("replication mrf: unknown version: %d", binary.LittleEndian.Uint16(data[2:4]))
		}

		// OK, parse data.
		// ignore any parsing errors, we do not care this file is generated again anyways.
		re.DecodeMsg(msgp.NewReader(rc))

		return re, nil
	}

	globalLocalDrivesMu.RLock()
	localDrives := cloneDrives(globalLocalDrivesMap)

		writeErrorResponse(ctx, w, apiErr, r.URL)
		return
	}

	if keyName, ok := formValues["Key"]; !ok {
		apiErr := errorCodes.ToAPIErr(ErrMalformedPOSTRequest)
		apiErr.Description = fmt.Sprintf("%s (%v)", apiErr.Description, errors.New("The name of the uploaded key is missing"))
		writeErrorResponse(ctx, w, apiErr, r.URL)
		return

    /** HTTP transport for OpenID Connect requests. */
    protected final HttpTransport httpTransport = new NetHttpTransport();

    /** JSON factory for OpenID Connect response parsing. */
    protected final JsonFactory jsonFactory = GsonFactory.getDefaultInstance();

    /**
     * Initializes the OpenID Connect authenticator.
     */
    @PostConstruct
    public void init() {

		if err != nil {
			return Config{}, err
		}
	} else {
		cfg.RRS.Parity = defaultRRSParity
		if setDriveCount == 1 {
			cfg.RRS.Parity = 0
		}
	}

	// Validation is done after parsing both the storage classes. This is needed because we need one
	// storage class value to deduce the correct value of the other storage class.
	if err = validateParity(cfg.Standard.Parity, cfg.RRS.Parity, setDriveCount); err != nil {

   * also be non-null.
   *
   * <p>If either or both endpoints are not already present in this graph, this method will silently
   * {@link #addNode(Object) add} each missing endpoint to the graph.
   *
   * <p>If {@code edge} already connects an endpoint pair equal to {@code endpoints}, then this
   * method will have no effect.
   *

///

### [Webargs](https://webargs.readthedocs.io/en/latest/) { #webargs }

Otra gran funcionalidad requerida por las APIs es el <dfn title="lectura y conversión a datos de Python">parsing</dfn> de datos de las requests entrantes.

Webargs es una herramienta que fue creada para proporcionar esa funcionalidad sobre varios frameworks, incluido Flask.

///

### [Webargs](https://webargs.readthedocs.io/en/latest/) { #webargs }

Outra grande funcionalidade requerida pelas APIs é o <dfn title="ler e converter para dados do Python">parsing</dfn> de dados vindos de requisições de entrada.

Webargs é uma ferramenta feita para fornecer isso no topo de vários frameworks, inclusive Flask.