log.error("Failed to create Mac instance for signing", e);
                throw new RuntimeException("Failed to create Mac instance", e);
            }

            mac.update(data, offset, length);
            final byte[] sig = mac.doFinal();
            System.arraycopy(sig, 0, data, offset + SIGNATURE_OFFSET, SIGNATURE_LENGTH);
        } finally {
            this.signingLock.unlock();

        if (text == null) {
            return null;
        }

        final MessageDigest msgDigest = getInstance(algorithm);
        try {
            msgDigest.update(text.getBytes("UTF-8"));
        } catch (final UnsupportedEncodingException e) {
            throw new ClIllegalStateException(e);
        }
        final byte[] digest = msgDigest.digest();

                                        }
                                    }
                                },
                            },
                        },
                        "summary": "Update Item",
                        "operationId": "update_item_items__item_id__put",
                        "requestBody": {
                            "content": {
                                "application/json": {

		fieldSize := int(extra.uint16())
		if len(extra) < fieldSize {
			break
		}
		fieldBuf := extra.sub(fieldSize)

		switch fieldTag {
		case zip64ExtraID:
			f.zip64 = true

			// update directory values from the zip64 extra block.
			// They should only be consulted if the sizes read earlier
			// are maxed out.
			// See golang.org/issue/13367.
			if needUSize {
				needUSize = false

    )
    cookie_values, cookie_errors = request_params_to_args(
        dependant.cookie_params, request.cookies
    )
    values.update(path_values)
    values.update(query_values)
    values.update(header_values)
    values.update(cookie_values)
    errors += path_errors + query_errors + header_errors + cookie_errors
    if dependant.body_params:
        (
            body_values,

                                        }
                                    }
                                },
                            },
                        },
                        "summary": "Update Item",
                        "operationId": "update_item_items__item_id__put",
                        "parameters": [
                            {
                                "required": True,

<div class="screenshot">
<img src="/img/tutorial/sql-databases/image01.png">
</div>

## Оновіть застосунок кількома моделями { #update-the-app-with-multiple-models }

Тепер трохи **відрефакторимо** застосунок, щоб підвищити **безпеку** та **гнучкість**.

  private enum HashMethod {
    MESSAGE_DIGEST_API() {
      @Override
      public byte[] hash(Algorithm algorithm, byte[] input) {
        MessageDigest md = algorithm.getMessageDigest();
        md.update(input);
        return md.digest();
      }
    },
    HASH_FUNCTION_DIRECT() {
      @Override
      public byte[] hash(Algorithm algorithm, byte[] input) {

		//
		// GNU tar v1.27.1 applies global headers to subsequent records,
		// but does not do the following properly:
		//	* It does not treat an empty record as deletion.
		//	* It does not use subsequent global headers to update previous ones.
		//
		//	$ gnutar -tvf pax-global-records.tar
		//	---------- 0/0               0 2017-07-13 19:40 global1
		//	---------- 0/0               0 2017-07-13 19:40 file2

    }

    /**
     * Inserts a new user across all authentication chains.
     * @param user The user to insert.
     */
    public void insert(final User user) {
        chains().of(stream -> stream.forEach(c -> c.update(user)));
    }

    /**
     * Changes the password for a user across all authentication chains.
     * @param username The username for which to change the password.
     * @param password The new password.