How can I tell mapserver to ignore a filter that is set in a mapfile?

Question

How can I tell mapserver to ignore a filter that is set in a mapfile?

I am displaying a wms layer with point features using mapserver. In one of the layers in my mapfile I have defined a filter similar to this:

FILTER          "mycolumn='%myvalue%'"

such that I can use runtime substitution in a mapserver request similar to this one:

http://someurl.com/mapserv?map=mymap.map&layer=mylayer&mode=map&myvalue=thisvalue

This works just fine.

However, sometimes I would like to display the entire dataset and thus forcing mapserver to ignore the filter.

Is it possible to deactivate the filter in a request?

Answer 1

I'm not sure, but this trick may work:

1. Add FILTER to validation block of the layer's description, like this:

   LAYER
   ...
       VALIDATION
         'FILTER' '.'
       END
   ...
   

2. When you want to show all of the data in your layer, add the following string to your URL request :

   &map.layer[mylayer]=FILTER+("[mycolumn]"+~*+".")
   

I hope this will help.

Answer 2

A working solution is similar to what @seruva19 suggested. The trick is to add a boolean value to the filter as an alternative to the previous filter:

FILTER    "(mycolumn='%myvalue%') or %allvars%"

where the validation forces the value to be TRUE

VALIDATION
  ...
  "allvals"    "^TRUE$"
END

and the default of allvals is set to FALSE

METADATA
    ...
    'default_allvals'   'FALSE'
END

Answer 3

If I can help with this Answer. This two other solution.

Use a default value to void the filter clause.

VALIDATION
    myColumn'^[0-9]{1,2}$' 
    default_myColumn '0'
END

AND put the condition in the DATA

DATA "geometryColumn from (select * from MYTABLE where (('%myColumn%' = '0') or (myColumn='%myColumn%')) ) using srid 4326"

OR with a filter

Use a default value to void the filter clause.

VALIDATION
    myColumn'^[0-9]{1,2}$' 
    default_myColumn '0'
END
FILTER  ((('%myColumn%' = '0') or ([myColumn]='%myColumn%')))

Note than I expect an issue with single parenthesis with Oracle. I use double parenthesis to make it work correctly otherwise I got a full table scan. The debug show the Where clause with single parenthesis like that

WHERE   ( '0' = '0' ) OR ( myColumn= '0' )  AND …

with double parenthesis:

WHERE   (( '0' = '0' ) OR ( myColumn= '0' ))  AND …