if err != nil {
			return objInfo.ETag
		}
	}

	// As per AWS S3 Spec, ETag for SSE-C encrypted objects need not be MD5Sum of the data.
	// Since server side copy with same source and dest just replaces the ETag, we save
	// encrypted content MD5Sum as ETag for both SSE-C and SSE-KMS, we standardize the ETag
	// encryption across SSE-C and SSE-KMS, and only return last 32 bytes for SSE-C

      byte[] buf = new byte[min(bufSize, MAX_ARRAY_LEN - totalLen)];
      bufs.add(buf);
      int off = 0;
      while (off < buf.length) {
        // always OK to fill buf; its size plus the rest of bufs is never more than MAX_ARRAY_LEN
        int r = in.read(buf, off, buf.length - off);
        if (r == -1) {
          return combineBuffers(bufs, totalLen);
        }
        off += r;
        totalLen += r;

   * structure (to make it possible to throw ConcurrentModificationException in the iterator). Note
   * that we choose not to make this volatile, so we do less of a "best effort" to track such
   * errors, for better performance.
   */
  private transient int metadata;

  /** The number of elements contained in the set. */
  private transient int size;

pkg database/sql, method (*DB) Conn(context.Context) (*Conn, error)
pkg database/sql, type Conn struct
pkg database/sql, type Out struct
pkg database/sql, type Out struct, Dest interface{}
pkg database/sql, type Out struct, In bool
pkg database/sql, var ErrConnDone error
pkg database/sql/driver, type NamedValueChecker interface { CheckNamedValue }

* 基本的なユーザーモデル (任意の修正や削除が可能)。
* **Alembic** マイグレーション。
* **CORS** (Cross Origin Resource Sharing (オリジン間リソース共有))。
* **Celery** ワーカー。バックエンドの残りの部分からモデルとコードを選択的にインポートし、使用可能。
* Dockerと統合された**Pytest**ベースのRESTバックエンドテスト。データベースに依存せずに、全てのAPIをテスト可能。Docker上で動作するので、毎回ゼロから新たなデータストアを構築可能。(ElasticSearch、MongoDB、CouchDBなどを使用して、APIの動作をテスト可能)
* Atom HydrogenやVisual Studio Code Jupyterなどの拡張機能を使用した、リモートまたはDocker開発用の**Jupyterカーネル**との簡単なPython統合。

            sessionChannels.remove(sessionId);
            throw new CIFSException("Failed to create channels for session " + sessionId, e);
        }
    }

    /**
     * Selects the best channel for an operation.
     *
     * @param sessionId the session identifier
     * @return the selected channel, or null if no channels available
     */
    public ChannelInfo selectChannel(String sessionId) {

---

**FastAPI** doesn't make any compromise with any database, data model or tool.

It gives you all the flexibility to choose the ones that fit your project the best.

And you can use directly many well maintained and widely used packages like `passlib` and `PyJWT`, because **FastAPI** doesn't require any complex mechanisms to integrate external packages.

   * building caches whose key or value types are incompatible with the types accepted by the
   * weigher already provided; the {@code CacheBuilder} type cannot do this. For best results,
   * simply use the standard method-chaining idiom, as illustrated in the documentation at top,
   * configuring a {@code CacheBuilder} and building your {@link Cache} all in a single statement.
   *

We will create a FastAPI **dependency** with `yield` that will provide a new `Session` for each request. This is what ensures that we use a single session per request. 🤓

Then we create an `Annotated` dependency `SessionDep` to simplify the rest of the code that will use this dependency.

{* ../../docs_src/sql_databases/tutorial001_an_py310.py ln[25:30]  hl[25:27,30] *}

### Create Database Tables on Startup { #create-database-tables-on-startup }

/// tip

This is a somewhat advanced technique, and in most of the cases you won't really need it, as you can raise exceptions (including `HTTPException`) from inside of the rest of your application code, for example, in the *path operation function*.

But it's there for you if you need it. 🤓

///

{* ../../docs_src/dependencies/tutorial008b_an_py39.py hl[18:22,31] *}