JS-Rewrite: Preserve query string rewrite when the request contains a body

[jjrodrig]

Overview

During the porting of rewrite_js.js tests into the elixir test suite I've found an erroneous behavior in the JS-rewrite functionality.

When a rewritten request contains a BODY (POST/PUT) and the rewrite rule rewrites the query string, this query string is ignored in the final request. The following case illustrates this issue.

1 - Create a design document with a rule that rewrites the query string, like this one:

 {
      "_id": "_design/n", 
      "rewrites": "function (r) { return {path: '../../_changes', query: {'filter': '_doc_ids'}};};"
    }

any request should be rewritten to _changes?filter=_docs_ids

curl -XPOST -u adm:pass -H "Content-type: application/json" \
   -d '{"_id": "_design/n", "rewrites": "function (r) { return {path: '\''../../_changes'\'', query: {'\''filter'\'': '\''_doc_ids'\''}};};"}' \
   https://127.0.0.1:15984/test

2 - Create a couple of docs

curl -XPUT -u adm:pass -H "Content-type: application/json" -d '{}' https://127.0.0.1:15984/test/1 
curl -XPUT -u adm:pass -H "Content-type: application/json" -d '{}' https://127.0.0.1:15984/test/2

3 - Perform a POST request to be rewritten

 curl -XPOST -u adm:pass -H "Content-type: application/json" \
    -d '{"doc_ids": ["2"]}' \
     https://127.0.0.1:15984/test/_design/n/_rewrite

The expected result for this case is to have only the change for the doc with id 2 in the response, but the full change list is returned. The filter=_doc_ids is ignored after the rewritten.

This PR changes this behavior and the query string is preserved, so the result for the previous case is the excepted one returning only the change for the doc with id 2.

Testing recommendations

The previous test case has been added to rewrite_js.js tests

 make javascript suites="rewrite_js, rewrite"

Related Issues or Pull Requests

This issue #1612 and the companion PR #1620 are related to this issue

Checklist

• Code is written and works correctly
• Changes are covered by tests
• Any new configurable parameters are documented in rel/overlay/etc/default.ini
• A PR for documentation changes has been made in https://github.com/apache/couchdb-documentation