MapScript: allow multiple CGI parameters with same key

[fschindler]

Currently, MapScript CGI request objects are only able to add unique keys, all other calls to setParameter with the same key overwrite the previously inserted key-value pair.

The problem with that behavior is that it is inconsistent with standard CGI MapServer dispatches.

The following string, for example is perfectly legal with MapServer in CGI mode, but impossible to rebuild with MapScript:

http://someurl?service=WCS&version=2.0.0&request=GetCoverage&coverageid=id&size=x(100)&size=y(100)

This is a real world example, which makes it impossible for a MapScript application to be compliant to the current ​WCS 2.0 interface standard. In this specific situation the problem is circumvented in the msWCSParseRequest20 function by checking certain keys only to a certain character index. This allows constructs like size_x or resolution_y which are possible to insert with MapScript. But this is definitely not ideal.

My proposed solution is to add an additional MapScript function to allow a non-overwriting addition of a key-value pair to a CGI request object, for example named addParameter. This would allow to let the following Python code to function as expected:

ows_req = mapscript.OWSRequest()
ows_req.addParameter("service", "WCS")
ows_req.addParameter("version", "2.0.0")
ows_req.addParameter("request", "GetCoverage")
ows_req.addParameter("coverageid", "id")
ows_req.addParameter("size", "x(100)")
ows_req.addParameter("size", "y(100)")
map.OWSDispatch(ows_req)

[fschindler]

Reference implementation for the depickted problem

[fschindler]

The patch ​http://trac.osgeo.org/mapserver/attachment/ticket/3973/r11972_cgirequestobj_addparam.patch implements the proposed function addParameter for both SWIG MapScript and PHP MapScript.

[fschindler]

Reworked patch for swig/php mapscript. Also contains updated documentation.

[fschindler]

r11972_cgirequestobj_addparam.patch is now obsolete, r11973_mapscript_owsrequest_addparameter.patch includes all previous changes (plus a fix) and adds documentation

[aboudreault]

fschindler, I tested a php script and it works well.

[schpidi]

Thanks for testing.

Committed patch with r12507.