# Header Parameter Models { #header-parameter-models }

If you have a group of related **header parameters**, you can create a **Pydantic model** to declare them.

This would allow you to **re-use the model** in **multiple places** and also to declare validations and metadata for all the parameters at once. 😎

/// note

This is supported since FastAPI version `0.115.0`. 🤓

///

```Python
commons: Annotated[dict, Depends(common_parameters)]
```

But because we are using `Annotated`, we can store that `Annotated` value in a variable and use it in multiple places:

{* ../../docs_src/dependencies/tutorial001_02_an_py310.py hl[12,16,21] *}

/// tip

This is just standard Python, it's called a "type alias", it's actually not specific to **FastAPI**.

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     *
     * @param policyHandle the policy handle to close
     */
    public MsrpcSamrCloseHandle(final rpc.policy_handle policyHandle) {
        super(policyHandle);
        ptype = 0;
        flags = DCERPC_FIRST_FRAG | DCERPC_LAST_FRAG;
    }

`Header` es una clase "hermana" de `Path`, `Query` y `Cookie`. También hereda de la misma clase común `Param`.

Pero recuerda que cuando importas `Query`, `Path`, `Header`, y otros de `fastapi`, en realidad son funciones que retornan clases especiales.

///

/// info | Información

Para declarar headers, necesitas usar `Header`, porque de otra forma los parámetros serían interpretados como parámetros de query.

///

## Conversión automática

     */
    public MsrpcQueryInformationPolicy(final LsaPolicyHandle policyHandle, final short level, final NdrObject info) {
        super(policyHandle, level, info);
        this.ptype = 0;
        this.flags = DCERPC_FIRST_FRAG | DCERPC_LAST_FRAG;
    }

        super(server, 200, 0xFFFF, new netdfs.DfsEnumStruct(), new NdrLong(0));
        this.info.level = this.level;
        this.info.e = new netdfs.DfsEnumArray200();
        this.ptype = 0;
        this.flags = DCERPC_FIRST_FRAG | DCERPC_LAST_FRAG;
    }

    /**
     * Returns the DFS root entries retrieved from the enumeration.
     *
     * @return an array of FileEntry objects representing the DFS roots
     */

     */
    public MsrpcSamrOpenAlias(final SamrDomainHandle handle, final int access, final int rid, final SamrAliasHandle aliasHandle) {
        super(handle, access, rid, aliasHandle);
        this.ptype = 0;
        this.flags = DCERPC_FIRST_FRAG | DCERPC_LAST_FRAG;
    }

        }

        @Test
        @DisplayName("Should handle file attributes with multiple flags set")
        void testMultipleFileAttributeFlags() throws SMBProtocolDecodingException {
            // Given
            byte[] buffer = new byte[60];
            SMBUtil.writeInt2(60, buffer, 0);

            // Set multiple attribute flags
            int attributes = 0x01 | 0x02 | 0x04 | 0x10 | 0x20; // Multiple attributes

        qos.length = 12;
        qos.impersonation_level = 2;
        qos.context_mode = 1;
        qos.effective_only = 0;
        object_attributes.security_quality_of_service = qos;
        ptype = 0;
        flags = DCERPC_FIRST_FRAG | DCERPC_LAST_FRAG;
    }