Si quieres recibir actualizaciones parciales, es muy útil usar el parámetro `exclude_unset` en el `.model_dump()` del modelo de Pydantic.

Como `item.model_dump(exclude_unset=True)`.

Eso generaría un `dict` solo con los datos que se establecieron al crear el modelo `item`, excluyendo los valores por defecto.

app = FastAPI()

items = {"foo": "The Foo Wrestlers"}


@app.get("/items/{item_id}")
async def read_item(item_id: str):
    if item_id not in items:
        raise HTTPException(status_code=404, detail="Item not found")

        List<Element> matches = new ArrayList<Element>();
        NodeList childNodes = element.getChildNodes();
        for (int i = 0; i < childNodes.getLength(); i++) {
            Node node = childNodes.item(i);
            if (node instanceof Element) {
                Element childElement = (Element) node;
                if (childElement.getTagName().equals(childName)) {
                    matches.add(childElement);

///

## テンプレートの作成 { #writing-templates }

例えば、`templates/item.html` に次のようなテンプレートを書きます:

```jinja hl_lines="7"
{!../../docs_src/templates/templates/item.html!}
```

### テンプレートのコンテキスト値 { #template-context-values }

次のような HTML 内で:

{% raw %}

```jinja
Item ID: {{ id }}
```

{% endraw %}

...渡した "context" の `dict` から取得した `id` が表示されます:

```Python

        i++;
        len |= 0xff & buf[i++];

        // MECH_OID
        if (buf.length < i + len) {
            throw new IllegalArgumentException();
        }
        final byte[] bo = new byte[len];
        System.arraycopy(buf, i, bo, 0, len);
        i += len;
        this.oid = ASN1ObjectIdentifier.getInstance(bo);

        // NAME_LEN
        if (buf.length < i + NAME_LEN_SIZE) {

        bufferIndex += 4;
        this.messageLength = SMBUtil.readInt4(buffer, bufferIndex);
        bufferIndex += 4;
        this.data = new byte[len - 16];
        if (this.data.length > 0) {
            System.arraycopy(buffer, bufferIndex, this.data, 0, this.data.length);
        }
        return bufferIndex - start;
    }

    /**
     * Write the lease key to a buffer
     *
     * @param dst destination buffer
     * @param dstIndex starting index in destination buffer
     */
    public void encode(byte[] dst, int dstIndex) {
        System.arraycopy(key, 0, dst, dstIndex, LEASE_KEY_SIZE);
    }

    /**
     * Check if this is a zero key (all bytes are zero)
     *
     * @return true if all bytes are zero
     */
    public boolean isZero() {

            if (propValue.startsWith("!")) {
                reverseValue = true;
                propValue = propValue.substring(1);
            }

            // we have a value, so it has to match the system value...
            boolean result = propValue.equals(sysValue);

            return reverseValue ? !result : result;
        } else {
            boolean result = StringUtils.isNotEmpty(sysValue);

		},
	}
	for i, test := range cases {
		listKey, item := splitPath(test.path, test.secondIndex)
		if listKey != test.expectedListKey || item != test.expectedItem {
			t.Errorf("unexpected result on test[%v]: expected[%s, %s] but got [%s, %s]", i, test.expectedListKey, test.expectedItem, listKey, item)
		}
	}

@app.get("/items-header/{item_id}")
async def read_item_header(item_id: str):
    if item_id not in items:
        raise HTTPException(
            status_code=404,
            detail="Item not found",
            headers={"X-Error": "There goes my error"},
        )