*/
@GwtCompatible
public abstract class AbstractSequentialIterator<T> extends UnmodifiableIterator<T> {
  private @Nullable T nextOrNull;

  /**
   * Creates a new iterator with the given first element, or, if {@code firstOrNull} is null,
   * creates a new empty iterator.
   */
  protected AbstractSequentialIterator(@Nullable T firstOrNull) {
    this.nextOrNull = firstOrNull;
  }

  /**

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

func SaveBeforeAssociations(create bool) func(db *gorm.DB) {
	return func(db *gorm.DB) {
		if db.Error == nil && db.Statement.Schema != nil {
			selectColumns, restricted := db.Statement.SelectAndOmitColumns(create, !create)

			// Save Belongs To associations
			for _, rel := range db.Statement.Schema.Relationships.BelongsTo {

        project.getPluginManager().apply(RestResourcesPlugin.class);

        // create source set
        SourceSetContainer sourceSets = project.getExtensions().getByType(SourceSetContainer.class);
        SourceSet yamlTestSourceSet = sourceSets.create(SOURCE_SET_NAME);

        registerTestTask(project, yamlTestSourceSet);

        // setup the dependencies

                .when()
                .post(getEsUrl() + "/_bulk");
        given().contentType("application/json").when().post(getEsUrl() + "/_refresh");
        logger.info("Created Token: {}", DEFAULT_TEST_TOKEN);
        return DEFAULT_TEST_TOKEN;
    }

    public static void deleteTestToken() {
        final String testToken = System.getProperty(TEST_TOKEN);
        if (testToken != null) {

你可能之前已经了解到，你可以设置默认的[响应状态码](../tutorial/response-status-code.md)。

但在某些情况下，你需要返回一个不同于默认值的状态码。

## 使用场景 { #use-case }

例如，假设你想默认返回一个HTTP状态码为“OK”`200`。

但如果数据不存在，你想创建它，并返回一个HTTP状态码为“CREATED”`201`。

但你仍然希望能够使用`response_model`过滤和转换你返回的数据。

对于这些情况，你可以使用一个`Response`参数。

## 使用 `Response` 参数 { #use-a-response-parameter }

你可以在你的*路径操作函数*中声明一个`Response`类型的参数（就像你可以为cookies和头部做的那样）。

from pydantic import BaseModel

app = FastAPI()

reusable_oauth2 = OAuth2(
    flows={
        "password": {
            "tokenUrl": "token",
            "scopes": {"read:users": "Read the users", "write:users": "Create users"},
        }
    },
    auto_error=False,
)


class User(BaseModel):
    username: str


def get_current_user(oauth_header: str | None = Security(reusable_oauth2)):

///

### Step 2: create a `FastAPI` "instance" { #step-2-create-a-fastapi-instance }

{* ../../docs_src/first_steps/tutorial001_py310.py hl[3] *}

Here the `app` variable will be an "instance" of the class `FastAPI`.

This will be the main point of interaction to create all your API.

### Step 3: create a *path operation* { #step-3-create-a-path-operation }

#### Path { #path }

 * This class encapsulates HTTP request parameters that can have multiple values,
 * such as query parameters, form parameters, or other request-related data.
 *
 * <p>This class is immutable and thread-safe. Once created, the parameter name
 * and values cannot be modified.</p>
 *
 */
public class RequestParameter {

    /** The name of the request parameter. */
    private final String name;

private const val OCTETS_TO_ADD_BEFORE_INFLATION = 0x0000ffff

class MessageInflater(
  private val noContextTakeover: Boolean,
) : Closeable {
  private val deflatedBytes = Buffer()

  // Lazily-created.
  private var inflater: Inflater? = null
  private var inflaterSource: InflaterSource? = null

  /** Inflates [buffer] in place as described in RFC 7692 section 7.2.2. */
  @Throws(IOException::class)

import org.apache.maven.api.annotations.Nonnull;
import org.apache.maven.api.annotations.Nullable;

/**
 * A range of versions.
 *
 * {@code VersionConstraint} objects are created using the
 * {@linkplain org.apache.maven.api.services.VersionParser} service.
 *
 * @see Version
 * @see VersionConstraint
 * @see org.apache.maven.api.services.VersionParser#parseVersionRange(String)