///

```Python
commons = Depends(CommonQueryParams)
```

////

...as in:

{* ../../docs_src/dependencies/tutorial003_an_py310.py hl[19] *}

But declaring the type is encouraged as that way your editor will know what will be passed as the parameter `commons`, and then it can help you with code completion, type checks, etc:

<img src="/img/tutorial/dependencies/image02.png">

{* ../../docs_src/extra_models/tutorial004_py39.py hl[18] *}

## Response with arbitrary `dict` { #response-with-arbitrary-dict }

You can also declare a response using a plain arbitrary `dict`, declaring just the type of the keys and values, without using a Pydantic model.

This is useful if you don't know the valid field/attribute names (that would be needed for a Pydantic model) beforehand.

For example, in this application we don't use FastAPI's integrated functionality to extract the JSON Schema from Pydantic models nor the automatic validation for JSON. In fact, we are declaring the request content type as YAML, not JSON:

{* ../../docs_src/path_operation_advanced_configuration/tutorial007_py39.py hl[15:20, 22] *}

//
// In most cases, new([Buffer]) (or just declaring a [Buffer] variable) is
// sufficient to initialize a [Buffer].
func NewBuffer(buf []byte) *Buffer { return &Buffer{buf: buf} }

// NewBufferString creates and initializes a new [Buffer] using string s as its
// initial contents. It is intended to prepare a buffer to read an existing
// string.
//
// In most cases, new([Buffer]) (or just declaring a [Buffer] variable) is

        assertTrue(
                projects.contains(pluginLevelDepProject),
                "Expected " + projects + " to contain " + pluginLevelDepProject);

        // the declaring project MUST be listed after the plugin and its plugin-level dep, though.
        assertEquals(declaringProject, projects.get(3));
    }

    @Test

Then you declare your data model as a class that inherits from `BaseModel`.

Use standard Python types for all the attributes:

{* ../../docs_src/body/tutorial001_py310.py hl[5:9] *}


The same as when declaring query parameters, when a model attribute has a default value, it is not required. Otherwise, it is required. Use `None` to make it just optional.

For example, this model above declares a JSON "`object`" (or Python `dict`) like:

current_user --> public
active_user --> private
admin_user --> activate_user
paying_user --> pro_items
```

## Integrated with **OpenAPI** { #integrated-with-openapi_1 }

All these dependencies, while declaring their requirements, also add parameters, validations, etc. to your *path operations*.

Now, as Swagger UI didn't support multiple JSON Schema examples (as of 2023-08-26), users didn't have a way to show multiple examples in the docs.

To solve that, FastAPI `0.103.0` **added support** for declaring the same old **OpenAPI-specific** `examples` field with the new parameter `openapi_examples`. 🤓

### Summary { #summary }

It used custom types in its declarations instead of standard Python types, but it was still a huge step forward.

It also was one of the first frameworks to generate a custom schema declaring the whole API in JSON.

It was not based on a standard like OpenAPI and JSON Schema. So it wouldn't be straightforward to integrate it with other tools, like Swagger UI. But again, it was a very innovative idea.

        /*
         * These classes handle null properly but throw IllegalArgumentException for the default
         * Class argument that this test uses. Normally we'd fix that by declaring a
         * ReflectionFreeAssertThrowsTest with a testNulls method, but that's annoying to have to do
         * for a package-private utility class. So we skip the class entirely instead.
         */
        continue;