In the same way that you can declare more validations and metadata for query parameters with Query, you can declare the same type of validations and metadata for path parameters with Path.
First, import Path from fastapi, and import Annotated:
=== "Python 3.10+"
```Python hl_lines="1 3"
{!> ../../../docs_src/path_params_numeric_validations/tutorial001_an_py310.py!}
```
=== "Python 3.9+"
```Python hl_lines="1 3"
{!> ../../../docs_src/path_params_numeric_validations/tutorial001_an_py39.py!}
```
=== "Python 3.6+"
```Python hl_lines="3-4"
{!> ../../../docs_src/path_params_numeric_validations/tutorial001_an.py!}
```
=== "Python 3.10+ non-Annotated"
!!! tip
Prefer to use the `Annotated` version if possible.
```Python hl_lines="1"
{!> ../../../docs_src/path_params_numeric_validations/tutorial001_py310.py!}
```
=== "Python 3.6+ non-Annotated"
!!! tip
Prefer to use the `Annotated` version if possible.
```Python hl_lines="3"
{!> ../../../docs_src/path_params_numeric_validations/tutorial001.py!}
```
!!! info
FastAPI added support for Annotated (and started recommending it) in version 0.95.0.
If you have an older version, you would get errors when trying to use `Annotated`.
Make sure you [Upgrade the FastAPI version](../deployment/versions.md#upgrading-the-fastapi-versions){.internal-link target=_blank} to at least 0.95.1 before using `Annotated`.
You can declare all the same parameters as for Query.
For example, to declare a title metadata value for the path parameter item_id you can type:
=== "Python 3.10+"
```Python hl_lines="10"
{!> ../../../docs_src/path_params_numeric_validations/tutorial001_an_py310.py!}
```
=== "Python 3.9+"
```Python hl_lines="10"
{!> ../../../docs_src/path_params_numeric_validations/tutorial001_an_py39.py!}
```
=== "Python 3.6+"
```Python hl_lines="11"
{!> ../../../docs_src/path_params_numeric_validations/tutorial001_an.py!}
```
=== "Python 3.10+ non-Annotated"
!!! tip
Prefer to use the `Annotated` version if possible.
```Python hl_lines="8"
{!> ../../../docs_src/path_params_numeric_validations/tutorial001_py310.py!}
```
=== "Python 3.6+ non-Annotated"
!!! tip
Prefer to use the `Annotated` version if possible.
```Python hl_lines="10"
{!> ../../../docs_src/path_params_numeric_validations/tutorial001.py!}
```
!!! note A path parameter is always required as it has to be part of the path.
So, you should declare it with `...` to mark it as required.
Nevertheless, even if you declared it with `None` or set a default value, it would not affect anything, it would still be always required.
!!! tip
This is probably not as important or necessary if you use Annotated.
Let's say that you want to declare the query parameter q as a required str.
And you don't need to declare anything else for that parameter, so you don't really need to use Query.
But you still need to use Path for the item_id path parameter. And you don't want to use Annotated for some reason.
Python will complain if you put a value with a "default" before a value that doesn't have a "default".
But you can re-order them, and have the value without a default (the query parameter q) first.
It doesn't matter for FastAPI. It will detect the parameters by their names, types and default declarations (Query, Path, etc), it doesn't care about the order.
So, you can declare your function as:
=== "Python 3.6 non-Annotated"
!!! tip
Prefer to use the `Annotated` version if possible.
```Python hl_lines="7"
{!> ../../../docs_src/path_params_numeric_validations/tutorial002.py!}
```
But keep in mind that if you use Annotated, you won't have this problem, it won't matter as you're not using the function parameter default values for Query() or Path().
=== "Python 3.9+"
```Python hl_lines="10"
{!> ../../../docs_src/path_params_numeric_validations/tutorial002_an_py39.py!}
```
=== "Python 3.6+"
```Python hl_lines="9"
{!> ../../../docs_src/path_params_numeric_validations/tutorial002_an.py!}
```
!!! tip
This is probably not as important or necessary if you use Annotated.
Here's a small trick that can be handy, but you won't need it often.
If you want to:
- declare the
qquery parameter without aQuerynor any default value - declare the path parameter
item_idusingPath - have them in a different order
- not use
Annotated
...Python has a little special syntax for that.
Pass *, as the first parameter of the function.
Python won't do anything with that *, but it will know that all the following parameters should be called as keyword arguments (key-value pairs), also known as kwargs. Even if they don't have a default value.
{!../../../docs_src/path_params_numeric_validations/tutorial003.py!}Keep in mind that if you use Annotated, as you are not using function parameter default values, you won't have this problem, and you probably won't need to use *.
=== "Python 3.9+"
```Python hl_lines="10"
{!> ../../../docs_src/path_params_numeric_validations/tutorial003_an_py39.py!}
```
=== "Python 3.6+"
```Python hl_lines="9"
{!> ../../../docs_src/path_params_numeric_validations/tutorial003_an.py!}
```
With Query and Path (and others you'll see later) you can declare number constraints.
Here, with ge=1, item_id will need to be an integer number "greater than or equal" to 1.
=== "Python 3.9+"
```Python hl_lines="10"
{!> ../../../docs_src/path_params_numeric_validations/tutorial004_an_py39.py!}
```
=== "Python 3.6+"
```Python hl_lines="9"
{!> ../../../docs_src/path_params_numeric_validations/tutorial004_an.py!}
```
=== "Python 3.6+ non-Annotated"
!!! tip
Prefer to use the `Annotated` version if possible.
```Python hl_lines="8"
{!> ../../../docs_src/path_params_numeric_validations/tutorial004.py!}
```
The same applies for:
gt:greaterthanle:less than orequal
=== "Python 3.9+"
```Python hl_lines="10"
{!> ../../../docs_src/path_params_numeric_validations/tutorial005_an_py39.py!}
```
=== "Python 3.6+"
```Python hl_lines="9"
{!> ../../../docs_src/path_params_numeric_validations/tutorial005_an.py!}
```
=== "Python 3.6+ non-Annotated"
!!! tip
Prefer to use the `Annotated` version if possible.
```Python hl_lines="9"
{!> ../../../docs_src/path_params_numeric_validations/tutorial005.py!}
```
Number validations also work for float values.
Here's where it becomes important to be able to declare gt and not just ge. As with it you can require, for example, that a value must be greater than 0, even if it is less than 1.
So, 0.5 would be a valid value. But 0.0 or 0 would not.
And the same for lt.
=== "Python 3.9+"
```Python hl_lines="13"
{!> ../../../docs_src/path_params_numeric_validations/tutorial006_an_py39.py!}
```
=== "Python 3.6+"
```Python hl_lines="12"
{!> ../../../docs_src/path_params_numeric_validations/tutorial006_an.py!}
```
=== "Python 3.6+ non-Annotated"
!!! tip
Prefer to use the `Annotated` version if possible.
```Python hl_lines="11"
{!> ../../../docs_src/path_params_numeric_validations/tutorial006.py!}
```
With Query, Path (and others you haven't seen yet) you can declare metadata and string validations in the same ways as with Query Parameters and String Validations{.internal-link target=_blank}.
And you can also declare numeric validations:
gt:greaterthange:greater than orequallt:lessthanle:less than orequal
!!! info
Query, Path, and other classes you will see later are subclasses of a common Param class.
All of them share the same parameters for additional validation and metadata you have seen.
!!! note "Technical Details"
When you import Query, Path and others from fastapi, they are actually functions.
That when called, return instances of classes of the same name.
So, you import `Query`, which is a function. And when you call it, it returns an instance of a class also named `Query`.
These functions are there (instead of just using the classes directly) so that your editor doesn't mark errors about their types.
That way you can use your normal editor and coding tools without having to add custom configurations to disregard those errors.