## 响应模型的编码参数 { #response-model-encoding-parameters }

你的响应模型可以具有默认值，例如：

{* ../../docs_src/response_model/tutorial004_py310.py hl[9,11:12] *}

* `description: Union[str, None] = None`（或在 Python 3.10 中的 `str | None = None`）默认值为 `None`。
* `tax: float = 10.5` 默认值为 `10.5`。
* `tags: List[str] = []` 默认值为一个空列表：`[]`。

但如果它们并没有被实际存储，你可能希望在结果中省略这些默认值。

{* ../../docs_src/response_model/tutorial003_04_py310.py hl[8] *}

...これは、型アノテーションがPydantic型ではなく、単一の `Response` クラス（またはサブクラス）でもないために失敗します。`Response` と `dict` の間のunion（どちらか）になっているからです。

### レスポンスモデルを無効化する { #disable-response-model }

上の例を続けると、FastAPIが実行するデフォルトのデータ検証、ドキュメント化、フィルタリングなどを行いたくないこともあるでしょう。

しかし、エディタや型チェッカー（例: mypy）などのツール支援を得るために、関数の戻り値の型アノテーションは残したいかもしれません。

    TreeRangeSet<C> result = create();
    result.addAll(rangeSet);
    return result;
  }

  /**
   * Returns a {@code TreeRangeSet} representing the union of the specified ranges.
   *
   * <p>This is the smallest {@code RangeSet} which encloses each of the specified ranges. An
   * element will be contained in this {@code RangeSet} if and only if it is contained in at least

      assertThat(removalNotifications.get("b" + i)).isEqualTo("b" + i);
    }

    // Each of the values added to the map should either still be there, or have seen a removal
    // notification.
    assertThat(Sets.union(cache.asMap().keySet(), removalNotifications.keySet()))
        .isEqualTo(expectedKeys);
    assertThat(cache.asMap().keySet()).containsNoneIn(removalNotifications.keySet());
    threadPool.shutdown();

  // Element-level accessors
  //

  /**
   * Returns a live view of the edges whose {@link #incidentNodes(Object) incident nodes} in this
   * network include {@code node}.
   *
   * <p>This is equal to the union of {@link #inEdges(Object)} and {@link #outEdges(Object)}.
   *
   * <p>If {@code node} is removed from the network after this method is called, the {@code Set}

      assertThat(removalNotifications.get("b" + i)).isEqualTo("b" + i);
    }

    // Each of the values added to the map should either still be there, or have seen a removal
    // notification.
    assertThat(Sets.union(cache.asMap().keySet(), removalNotifications.keySet()))
        .isEqualTo(expectedKeys);
    assertThat(cache.asMap().keySet()).containsNoneIn(removalNotifications.keySet());
    threadPool.shutdown();

	jt := JoinTable{UserID: 1, FriendID: 2}
	err := DB.Create(&jt).Error
	if err != nil {
		t.Errorf("No error should happen when create a record without a GORM primary key. But in the database this primary key exists and is the union of 2 or more fields\n But got: %s", err)
	}
}

func TestSelectWithCreate(t *testing.T) {

        when(mockNdrBuffer.dec_ndr_long()).thenReturn(1, 123); // _infop, retval
        when(mockNdrBuffer.dec_ndr_short()).thenReturn((int) (short) 0); // union discriminant

        queryInfoPolicy.decode_out(mockNdrBuffer);

        verify(mockInfo).decode(mockNdrBuffer);
        assertEquals(123, queryInfoPolicy.retval);
    }

    @Test

	if wantFormat := h.Format; wantFormat != FormatUnknown {
		if wantFormat.has(FormatPAX) && !preferPAX {
			wantFormat.mayBe(FormatUSTAR) // PAX implies USTAR allowed too
		}
		format.mayOnlyBe(wantFormat) // Set union of formats allowed and format wanted
	}
	if format == FormatUnknown {
		switch h.Format {
		case FormatUSTAR:
			err = headerError{"Format specifies USTAR", whyNoUSTAR, whyOnlyPAX, whyOnlyGNU}
		case FormatPAX:

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