[mapserver-users] runtime substitution DATA

[Steve Lime]

You should be able to use either approach. To change the whole thing you'd do:

  &map.layer[mylayer]=DATA+'some new SQL string'&...

but in this case you must set DATAPATTERN at the map level to a regular expression to use
to validate the new SQL. I think this is really hard to do properly and so should probably be
avoided.

Another alternative is replacing just parts of the SQL, kind of an SQL template approach, here's
an example I'm using in production now:

  DATA "point FROM (SELECT *,oid FROM sites2 WHERE has_telemetry ~ '%has_telemetry%' AND has_archive ~ '%has_archive%' AND has_water_chemistry ~ '%has_water_chemistry%' AND is_cwl_site ~ '%is_cwl_site%' AND is_flood_warning_gage ~ '%is_flood_warning_gage%') as foo USING UNIQUE oid USING SRID=-1"
    METADATA
      has_telemetry_validation_pattern '^[01.]$'
      has_archive_validation_pattern '^[01.]$'
      has_water_chemistry_validation_pattern '^[01.]$'
      is_cwl_site_validation_pattern '^[01.]$'
      is_flood_warning_gage_validation_pattern '^[01.]$'
    END

In this example my data contain 0 or 1 depending on the properties of a site. I want to allow the user 
to pick 0, 1 or either so I use regex's in PostgreSQL (hence the . being a legal character from my 
application. The validation patterns restrict input to 0,1 or . (e.g. either). Another example:

    DATA 'point FROM (select *,oid, substring(station from 2) as station_no_char from sites2 where oid=%id%) as foo USING UNIQUE oid USING SRID=-1'
    METADATA
      id_validation_pattern '^[0-9]{1,14}$'
    END

Here I'm using the oid to identify one site and the validation pattern to limit input to a sequence of 
numbers from 1 to 14 characters in length. If the value for "id" doesn't match then an error is thrown.

Steve

>>> On 2/25/2009 at 3:07 AM, in message <49A50A6E.90406 at neogeo-online.net>,
Guillaume Sueur <no-reply at neogeo-online.net> wrote:
> Hi list,
> 
> I'm trying to change the DATA statement of a PostGIS Layer on the fly,
> from a WMS request.
> I made it work for FILTER or EXPRESSION, but no success with DATA,
> either using my %PARAM% in the middle of the SQL string or for the whole
> thing.
> I've seen here (http://mapserver.org/cgi/runsub.html) that it should
> validate a DATAPATTERN.
> 
> Would someone have some clues about this ?
> 
> Thanks
> 
> Guillaume
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