Request validation
You can configure API Gateway to perform validation on a route request before proceeding with the integration request. If the validation fails, API Gateway fails the request without calling your backend, sends a "Bad request body" gateway response to the client, and publishes the validation results in CloudWatch Logs. Using validation this way reduces unnecessary calls to your API backend.
Model selection expressions
You can use a model selection expression to dynamically validate requests within the same
route. Model validation occurs if you provide a model selection expression for either
proxy or non-proxy integrations. You might need to define the $default
model as a fallback when no matching model is found. If there is no matching model and
$default isn't defined, the validation fails. The selection expression
looks like Route.ModelSelectionExpression and evaluates to the key for
Route.RequestModels.
When you define a route for a WebSocket API, you can optionally specify a model
selection expression. This expression is evaluated to select the model to
be used for body validation when a request is received. The expression evaluates to one
of the entries in a route's requestmodels.
A model is expressed as a JSON schema
