How to enable request validation?

Hi

I would like to enable request validation to my API, so I can stop invalid requests from invoking lambdas [1] and also make sure the data my users send is correct.

I've followed a couple of recommendations I found in this repo, and I used [leangle](https://github.com/aws/chalice/issues/1224#issuecomment-598215673) to add models. While the models are uploaded and are available in the API gateway console, and the Request Body is correctly assigned to my schema (called `TextSchema`), as seen in this screenshot the Request Validator setting is not set to _Validate body, query string parameters, and headers_ , and the request is not validated using the schema.

I've managed to make the Validator work by manually setting the correct value in the form, then deploying the API from the console, but as soon as I change something and deploy chalice from the cli (or the cdk) these values are reset and the API stops validating requests.

My API is experimental, so this is all the code

```
import leangle

from chalice import Blueprint
from marshmallow import Schema, fields

app = Blueprint("myApp")

@leangle.add_schema()
class TextSchema(Schema):
text = fields.Str()

@app.route('/test', methods=['POST'])
@leangle.describe.parameter(name='body', _in='body', description='Receive text', schema='TextSchema')
def process_text():
text = app.current_request.json_body['text']

return text
```

What is it that I am missing? Or is there a better way to do this?

Thank you

[1] https://dev.to/dvddpl/reduce-lambda-invocations-and-code-boilerplate-by-adding-a-json-schema-validator-to-your-api-gateway-15af

Reproduce the deployment using the Blueprint route, leangle schema decorators, and the shown CLI or CDK workflow, then compare the generated API Gateway model and request-validator settings. The issue is resolved when deployment preserves body validation and invalid requests are rejected before invoking the Lambda.

Written by the indexing model from the issue text.