mirror of
https://github.com/PaiGramTeam/sqlmodel.git
synced 2024-11-24 17:19:33 +00:00
65 lines
2.5 KiB
Markdown
65 lines
2.5 KiB
Markdown
# Read Heroes with Limit and Offset wtih FastAPI
|
|
|
|
When a client sends a request to get all the heroes, we have been returning them all.
|
|
|
|
But if we had **thousands** of heroes that could consume a lot of **computational resources**, network bandwith, etc.
|
|
|
|
So we probably want to limit it.
|
|
|
|
Let's use the same **offset** and **limit** we learned about in the previous tutorial chapters for the API.
|
|
|
|
!!! info
|
|
In many cases this is also called **pagination**.
|
|
|
|
## Add a Limit and Offset to the Query Parameters
|
|
|
|
Let's add `limit` and `offset` to the query parameters.
|
|
|
|
By default, we will return the first results from the database, so `offset` will have a default value of `0`.
|
|
|
|
And by default, we will return a maximum of `100` heroes, so `limit` will have a default value of `100`.
|
|
|
|
```Python hl_lines="3 9 11"
|
|
{!./docs_src/tutorial/fastapi/limit_and_offset/tutorial001.py[ln:1-4]!}
|
|
|
|
# Code here omitted 👈
|
|
|
|
{!./docs_src/tutorial/fastapi/limit_and_offset/tutorial001.py[ln:54-58]!}
|
|
|
|
# Code below omitted 👇
|
|
```
|
|
|
|
<details>
|
|
<summary>👀 Full file preview</summary>
|
|
|
|
```Python
|
|
{!./docs_src/tutorial/fastapi/limit_and_offset/tutorial001.py!}
|
|
```
|
|
|
|
</details>
|
|
|
|
We want to allow clients to set a different `offset` and `limit` values.
|
|
|
|
But we don't want them to be able to set a `limit` of something like `9999`, that's over `9000`! 😱
|
|
|
|
So, to prevent it, we add additional validation to the `limit` query parameter, declaring that it has to be **l**ess **t**han or **e**qual to `100` with `lte=100`.
|
|
|
|
This way, a client can decide to take less heroes if they want, but not more.
|
|
|
|
!!! info
|
|
If you need to refresh how query parameters and their validation work, check out the docs in FastAPI:
|
|
|
|
* <a href="https://fastapi.tiangolo.com/tutorial/query-params/" class="external-link" target="_blank">Query Parameters</a>
|
|
* <a href="https://fastapi.tiangolo.com/tutorial/query-params-str-validations/" class="external-link" target="_blank">Query Parameters and String Validations</a>
|
|
* <a href="https://fastapi.tiangolo.com/tutorial/path-params-numeric-validations/" class="external-link" target="_blank">Path Parameters and Numeric Validations</a>
|
|
|
|
## Check the Docs UI
|
|
|
|
Now we can see that the docs UI shows the new parameters to control **limit** and **offset** of our data.
|
|
|
|
<img class="shadow" alt="Interactive API docs UI" src="/img/tutorial/fastapi/limit-and-offset/image01.png">
|
|
|
|
## Recap
|
|
|
|
You can use **FastAPI**'s automatic data validation to get the parameters for `limit` and `offset`, and then use them with the **session** to control ranges of data to be sent in responses.
|