Ticket #318 (new enhancement)

Opened 5 years ago

Last modified 5 years ago

New QUERYABLE true/false layer parameter?

Reported by: dmorissette Assigned to: sdlime
Priority: high Milestone:
Component: MapServer C Library Version: 4.1
Severity: minor Keywords:
Cc:

Description

Subject:         Re: [Mapserver-dev] New QUERYABLE true/false layer parameter?
   Date:         Fri, 25 Apr 2003 14:00:38 -0500
   From:         "Steve Lime" <steve.lime@dnr.state.mn.us>
     To:         <morissette@dmsolutions.ca>, <mapserver-dev@lists.gis.umn.edu>

It would be cleaner certainly, I'm not sure of how big a change that
would be
though. The query functions all reference the msIsLayerQueryable (or
whatever
it's called function) so that's where the change would have to be made
so that
template would have the same meaning. The CGI code would have to be
checked
to make sure that TEMPLATE is used as a test rather then the above
function.

Steve

>>> Daniel Morissette <morissette@dmsolutions.ca> 04/23/03 03:54PM >>>
Steve, and all,

Since we are breaking with the past in many ways with this upcoming
release, perhaps now would be a good time to fix another annoying
issue:
the lack of a QUERYABLE flag in layer and class definitions.

I understand the logic and historical reasons behind the use of
TEMPLATE
to trigger queryability in the context of the mapserv CGI, but these
days there are lots of MapScript applications that end up having to
set
TEMPLATE "ttt" in their layer definitions just to make the layers
queryable, this is really not intuitive and sounds clunky when we have
to explain to a new user why things are this way.  There are also WMS
client layers that end up setting TEMPLATE "ttt" to indicate that the
layer on the remote server is queryable... we're very far from the
initial TEMPLATE idea.

What would you think of adding a QUERYABLE parameter to the LAYER and
CLASS definitions that dictates whether a layer is queryable or not? 
For mapserv CGI applications, the TEMPLATE value would still be
required, if TEMPLATE is not set for a queryable class or layer then
the
mapserv CGI would return an error.

Daniel

Change History

05/08/03 18:33:37 changed by sdlime

Dan: Thought about this some more. Seems to me that we need a single variable
that tells us if a layer is queryable. So, this parameter should be it. I would
propose  to update the code in mapfile.c that loads map files to set QUERYABLE
behind the scenes if TEMPLATE is set in the class or layer level. The only
problem this poses is in MapScript because you're accessing structure members
directly and don't have the opportunity to set multiple ones (without a helper
function). Thoughts?

Steve

07/10/03 00:44:41 changed by dmorissette

  • version changed from 4.0 to 4.1.
  • severity changed from normal to enhancement.
Too late for 4.0, let's revisit in 4.1