## Pydantic { #pydantic }

FastAPI 充分地利用了 [Pydantic](https://docs.pydantic.dev/) 的优势，用它在后台校验数据。众所周知，Pydantic 擅长的就是数据校验。

同样，`str`、`float`、`bool` 以及很多复合数据类型都可以使用类型声明。

接下来的章节会介绍其中的好几种。

## 顺序很重要 { #order-matters }

有时，*路径操作*中的路径是写死的。

比如要使用 `/users/me` 获取当前用户的数据。

然后还要使用 `/users/{user_id}`，通过用户 ID 获取指定用户的数据。

由于*路径操作*是按顺序依次运行的，因此，一定要在 `/users/{user_id}` 之前声明 `/users/me` ：

   * higher value than you need can waste space and time, and a significantly lower value can lead
   * to thread contention. But overestimates and underestimates within an order of magnitude do not
   * usually have much noticeable impact. A value of one permits only one thread to modify the map
   * at a time, but since read operations can proceed concurrently, this still yields higher

        <field xdoc.separator="blank">
          <name>activeProfiles</name>
          <version>1.0.0+</version>
          <description>
            List of manually-activated build profiles, specified in the order in which
            they should be applied.
          </description>
          <association>
            <type>String</type>
            <multiplicity>*</multiplicity>
          </association>
        </field>

            assertEquals(encoded, decoded);
            assertArrayEquals(ciphers, decodedContext.getCiphers());
        }

        @Test
        @DisplayName("Should preserve cipher order")
        void testCipherOrderPreservation() throws SMBProtocolDecodingException {
            int[] ciphers = { 5, 3, 1, 4, 2 };

				// number of items than number of online disks.
				inconsistent++
				continue
			}
			if meta.Erasure.Distribution[i] != meta.Erasure.Index {
				// Mismatch indexes with distribution order
				inconsistent++
			}
		}
	}

	erasureDistributionReliable := inconsistent <= len(partsMetadata)/2

	metaErrs := make([]error, len(errs))

	for i := range onlineDisks {

   * higher value than you need can waste space and time, and a significantly lower value can lead
   * to thread contention. But overestimates and underestimates within an order of magnitude do not
   * usually have much noticeable impact. A value of one permits only one thread to modify the map
   * at a time, but since read operations can proceed concurrently, this still yields higher

                warn(msg);
                acquiredProjectLock.lock();
            }
        }

        @Override
        public void close() {
            // release the lock in the reverse order of the acquisition
            acquiredProjectLock.unlock();
            acquiredAggregatorLock.unlock();
            mojos.remove(Thread.currentThread());
        }

        return String.join("\n", names);
    }

    public static String getDependencyName(Map<String, String> mappings, String dependencyName) {
        // order is the same for keys and values iteration since we use a linked hashmap
        List<String> mapped = new ArrayList<>(mappings.values());

   * invoked in the same order as the underlying service enters those states. Additionally, at most
   * one of the listener's callbacks will execute at once. However, multiple listeners' callbacks
   * may execute concurrently, and listeners may execute in an order different from the one in which
   * they were registered.
   *

                    throw new InvalidQueryException(
                            messages -> messages.addErrorsInvalidQueryUnsupportedSortOrder(UserMessages.GLOBAL_PROPERTY_KEY, values[1]),
                            "Invalid sort order: " + termQuery);
                }
            } else {
                sortOrder = SortOrder.ASC;
            }
            context.addSorts(createFieldSortBuilder(sortField, sortOrder));
        }));