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**FastAPI** will take care of solving them.

## First dependency "dependable" { #first-dependency-dependable }

You could create a first dependency ("dependable") like:

{* ../../docs_src/dependencies/tutorial005_an_py310.py hl[8:9] *}

It declares an optional query parameter `q` as a `str`, and then it just returns it.

This is quite simple (not very useful), but will help us focus on how the sub-dependencies work.

{* ../../docs_src/path_params_numeric_validations/tutorial004_an_py310.py hl[10] *}

## Number validations: greater than and less than or equal { #number-validations-greater-than-and-less-than-or-equal }

The same applies for:

* `gt`: `g`reater `t`han
* `le`: `l`ess than or `e`qual

{* ../../docs_src/path_params_numeric_validations/tutorial005_an_py310.py hl[10] *}

{* ../../docs_src/path_params_numeric_validations/tutorial003_an_py310.py hl[10] *}

## 數值驗證：大於或等於 { #number-validations-greater-than-or-equal }

使用 `Query` 和 `Path`（以及你之後會看到的其他類別）可以宣告數值限制。

這裡用 `ge=1`，代表 `item_id` 必須是「大於（`g`reater）或等於（`e`qual）」`1` 的整數。

{* ../../docs_src/path_params_numeric_validations/tutorial004_an_py310.py hl[10] *}

但如果你想讓它像宣告多個 Body 參數時那樣，期望一個帶有 `item` 鍵、其內含模型內容的 JSON，你可以使用 `Body` 的特殊參數 `embed`：

```Python
item: Item = Body(embed=True)
```

如下：

{* ../../docs_src/body_multiple_params/tutorial005_an_py310.py hl[17] *}

在此情況下 **FastAPI** 會期望如下的主體：

```JSON hl_lines="2"
{
    "item": {
        "name": "Foo",
        "description": "The pretender",
        "price": 42.0,
        "tax": 3.2