MapServer: Default spatial filter

Question

I have MapServer setup to display data (both WMS and WFS), however I'm having a problem adding a default filter.

There's is an area on the map that users should not be able to retrieve features from. I have the coordinates of this area so basically, I need to setup a default spatial filter to exclude features that are contained within this area. Removing the data itself isn't an option.

The layers are all OGR layers.

I can construct a client side filter to do this, however this should really be a server-side setting.

How should I go about doing this?

Ignoring the spatial requirement for a second, I'm having problems getting even a basic filter to work. If I append the following to the URL of a WFS request, this filter works as expected:

(Note this filter has no actual relevance, it's just a simple filter so I can check if it's being applied)

&FILTER="<PropertyIsGreaterThan><PropertyName>ID</PropertyName><Literal>916</Literal></PropertyIsGreaterThan>"

However, if in the map file I set the following:

LAYER ... FILTER "<PropertyIsGreaterThan><PropertyName>ID</PropertyName><Literal>916</Literal></PropertyIsGreaterThan>" ... END

Then I get no results from any query on that layer. Wrapping the filter in <Filter> tags has the same result.

I've also tried similar with the wfs_filter property, which doesn't seem to have any affect at all. (If I understand correctly, this is only used when using MapServer as a WFS Client?)

I'd appreciate any help.

Thanks :)

Answer 1

The filter you are trying to apply can only be applied from the client side. To apply a filter on the server side, you have to use an EXPRESSION at the CLASS level or a FILTER at the LAYER level. Note that spatial filter/expression may not work in FILTER. Here's an example:

LAYER
    DATA ....shp
    NAME "test"
    ...
    CLASS
        NAME "test"
        EXPRESSION       ([shape] disjoint fromText('POLYGON((0 0,0 90,180 90,180 0,0 0))'))
        STYLE
            ...
        END
    END
END

Refer to the EXPRESSION documentation for more details: http://mapserver.org/mapfile/expressions.html