[mapserver-users] Can you pass draw scale into postgis SQL?

[Stephen Woodbridge]

Open an enhancement request for this. If anyone has any additional 
thoughts on this please add them to the ticket.

Thanks,
   -Steve

Stephen Woodbridge wrote:
> Hi all,
> 
> I would like to be able to make my postgis queries in mapserver be aware 
> of the current draw scale. Is there an easy way to do this in the 
> mapfile? I would like to avoid parameter substitution since mapserver is 
> already aware of the scale, it would be nice if we could just embed a 
> token like [scale] in a mapserver data statement and mapserver would 
> substitute that for the current draw scale.
> 
> DATA "way from (
>   select way, osm_id, landuse, name
>     from osm_landuse1 where landuse is not null
>      and is_large_enough(area(way),'landuse1',[scale])
>   ) as foo using unique osm_id using srid=900913"
> 
> The idea here is that is_large_enough(area(way),'landuse1',[scale]) 
> whould return true or false based on comparing area(way) to some value 
> it looks up for 'landuse1' and the current [scale]. This would allow 
> dynamic filtering of data in the database based on the current scale.
> 
> Likewise you could use the [scale] in a SQL case statement to 
> dynamically change the SQL results based on scale.
> 
> It would seem that this could greatly simplify mapfiles.
> 
> -Steve W
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