API Gateway HTTP API Proxy Integration re-encodes the query parameters

Question

Hi,

Here is my configuration: 
mydomain.com -> API GW Custom Domain -> HTTP API -> Route (/api/{+proxy}) -> VPCLink -> ALB -> HTTPS Listener -> TargetGroup (Type: Instance) -> ECS Fargate Service

Our frontend clients sends an array as a query parameter but API GW encodes the parameters and the fargate application can not process the parameters. 
For example assume that client makes this request; https://mydomain.com/hello/world?key=value1,value2,value3
Request captured on backend is https://mydomain.com/hello/world?key=value1%2Cvalue2%2Cvalue3

How can I prevent this behavior? Is there any way?

Thanks

Accepted Answer

We solved the problem by decoding the parameters on backend application. "Thanks" to API Gateway there are no configuration options for this particular issue

Answer

It seems like URL encoding by default would be the expected behavior. If you have multiple values for the query string parameter (i.e. an array or collection) perhaps you should:

https://mydomain.com/hello/world?key=value1&key=value2&key=value3

API Gateway HTTP API Proxy Integration re-encodes the query parameters

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