[mapserver-users] Fwd: Zoom to something and display in one shot from MapServer CGI.

Wed Jul 12 08:41:42 PDT 2017

The shpext tag can re-project, format and buffer a shapes extent if that helps.

From: Basques, Bob (CI-StPaul) [mailto:bob.basques at ci.stpaul.mn.us]
Sent: Wednesday, July 12, 2017 8:37 AM
To: Lime, Steve D (MNIT) <steve.lime at state.mn.us>
Cc: Stephen Woodbridge <woodbri at swoodbridge.com>; mapserver-users at lists.osgeo.org
Subject: Re: [mapserver-users] Fwd: Zoom to something and display in one shot from MapServer CGI.

Steve (L),

That’s really close to what I was looking for.  I vaguely remembered something going on enhancement wise, related to URL requests inside of a MapServer request.

I’ll try this out and get back here with the results.

bobb

On Jul 11, 2017, at 4:55 PM, Lime, Steve D (MNIT) <steve.lime at state.mn.us<mailto:steve.lime at state.mn.us>> wrote:

You can also do pure mapserver with a query layer and a URL template. It's doing a dynamic redirect but it's a single call from your perspective. You'd have a layer like so:

LAYER
 NAME 'parcel_query'
 TYPE QUERY
 DATA 'parcels'
 VALIDATION
   qstring '^[0-9]{16}$' # 16-digit pin number
 END
 TEMPLATE 'http://{url to display service}&mapext=[shpext]'
END

and then a query URL like so:

 http://.../cgi-bin/mapserv?map=mymap.map?mode=itemquery&qlayer=parcels&qitem=pin&qstring=202923230045

Assumes one feature per pin...

It's not a pretty URL, if that's needed use a script as Steve suggests or something like mod_rewrite in front.

Steve

-----Original Message-----
From: mapserver-users [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of Stephen Woodbridge
Sent: Tuesday, July 11, 2017 1:07 PM
To: mapserver-users at lists.osgeo.org<mailto:mapserver-users at lists.osgeo.org>
Subject: Re: [mapserver-users] Fwd: Zoom to something and display in one shot from MapServer CGI.

Bobb,

If you using sql you can do this in one pass, just write a trivial php
script that returns an image.

1. connect to db
2. sql to query expanded bbox of parcel
   select st_astext(st_extent(st_expand(geom, delta)))
     from parcels where pin=?
3. create url to mapserver based on bbox and image size
5. header('Content-type: image/png');
4. passthru(url);

Don't make it more complicated than it needs to be. You can do the same
using perl, python, script language of your choice.

-Steve

On 7/11/2017 12:22 PM, Basques, Bob (CI-StPaul) wrote:

Hi Steve,

I want to send a CGI request like :  ServerName?pin=202923230045

And zoom to the pin (parcel polygon) in the returned image and also
add a buffer percentage.  This is for a reporting application.  I can
do it with an intermediate service, but it’s been awhile since I did
this, and was wondering if anything new in MapServer might help with
this for a single pass approach.

The zoom parameters would be hardcoded into the MapFILE in an ideal
world, I can build an SQL for this for example, but I recall I
couldn’t use the BBOX returned from the SQL as a BBOX for Mapserver
parent call, my memory is cloudy on that capability from MapServer
though, hence the question.  Now that you have me talking it through
though, I think the last time I asked about this it was to inquire
about possibly chaining more than one MapServer call together to get
the result.  I think there were fears at the time about possible
runaway processes being created . . . .

bobb

On Jul 11, 2017, at 10:38 AM, Stephen Woodbridge
<woodbri at swoodbridge.com<mailto:woodbri at swoodbridge.com> <mailto:woodbri at swoodbridge.com>> wrote:

On 7/11/2017 10:39 AM, Basques, Bob (CI-StPaul) wrote:

All,
It’s probably because it’s Tues. but I think I’ve asked this before
in the past . . .
I have a DB with PIN numbers for PARCELS and I want to be able to
auto-zoom(with buffer)  to a PARCEL by just sending in a PIN number
via CGI.
can the BBOX be pulled from the DB based on the geom in one shot?
I’ve done this in the past with a Webservice that went and grabbed
the BBOX separately, then assembled the url for getting the graphic
back from Mapserver.

Bobb,

What are you trying to zoom? the image or the client?

If it is the client then how is mapserver on the server supposed to
tell the client it needs to zoom? You have to query the server to get
the bbox then make the client zoom appropriately.

For the image, assuming you want a static image showing the parcel,
then I would write a php/python/perl script the you pass the PIN to
and it does the work to figure out the extents and return the image.

-Steve W

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