context#Bind show different behavior in different cases

[narrowizard]

Issue Description

I find that when calling ctx.Bind multi times, different params show different behaviors.
Cases:

1. PathParams can be bind multi times.
2. QueryParams can be bind multi times.
3. FormParams can be bind multi times. (Content-Type == "application/x-www-form-urlencoded" || Content-Type == "application/form-data")
4. JsonParams can only be bind once.(Content-Type == "application/json")
5. XmlParams can only be bind once.(Content-Type == "application/xml")

Reason

As metioned in related issues, request body as io.Reader will be consumed after reading.

Thinking(Important)

I think it's something about definition of Content#Bind method. It(Bind method) did two different things in above cases.

• In case 1,2,3, Bind method Bind params from context.pnames, content.pvalues, request.URL.Query(), request.Form which are idempotent in multiple calling.
• In case 4,5, Bind method read data from request body, and unmarshal to target interface{}.
  Will it be possible to do a data temp saving in content(like path params) in case 4,5, or restore data to request.Body after binding.

Checklist

• Dependencies installed
• No typos
• Searched existing issues and docs

Related Issues

#976, #782

[narrowizard]

@vishr

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.