AW: [MAPSERVER-USERS] Hiding overviews

[Daniel Morissette]

Daniel Morissette wrote:
> I had a quick look at this thread and it seems to me at first that using 
> GROUP in all layers corresponding to the same set of overviews should 
> allow you to turn all of them on/off at once.
> 

I built a small test case and it seems that the root problem is that the 
function msOWSMakeAllLayersUnique() produces an exception if any layer 
is missing a NAME. In order to allow what you want and make the layer 
name really optional we would need to get rid of that exception.

If we modify msOWSMakeAllLayersUnique() to 'continue' the loop instead 
of returning an exception when it encounters a NULL layer name as follows...

--- mapows.c    (revision 7477)
+++ mapows.c    (working copy)
@@ -141,10 +169,7 @@
        {
            if (GET_LAYER(map, i)->name == NULL || GET_LAYER(map, 
j)->name == NULL)
            {
-              msSetError(MS_MISCERR,
-                         "At least one layer is missing a name in map 
file.",
-                         "msOWSMakeAllLayersUnique()");
-              return MS_FAILURE;
+              continue;
            }
            if (strcasecmp(GET_LAYER(map, i)->name, GET_LAYER(map, 
j)->name) == 0 &&
                msRenameLayer((GET_LAYER(map, j)), ++count) != MS_SUCCESS)



... then the following mapfile block...

LAYER
   NAME layer1
   METADATA
     "wms_title" "Layer 1"
     "wms_group_title" "Group 1"
   END
   GROUP group1
   MINSCALE 0
   MAXSCALE 10000
   TYPE RASTER
   STATUS ON
   DATA layer1.tif
END

LAYER
   # NAME intentionally omitted...
   METADATA
     "wms_title" "Layer 2"
   END
   GROUP group1
   MINSCALE 10001
   MAXSCALE 100000
   TYPE RASTER
   STATUS ON
   DATA layer2.tif
END


... produces the following output in GetCapabilities ... this whole 
group can be turned on/off at once using LAYERS=group1 in the GetMap 
request. Notice that layer 2 has no name in GetCapabilities which is 
what we wanted. Omitting the layer name for layer 1 as well would make 
it non-selectable as well:

     <Layer>
       <Name>group1</Name>
       <Title>Group 1</Title>
       <Abstract>group1</Abstract>
       <Layer queryable="0">
         <Name>layer1</Name>

         <Title>Layer 1</Title>
         <ScaleHint min="0" max="4.98902848429637" />
       </Layer>
       <Layer queryable="0">
<!-- WARNING: Mandatory mapfile parameter 'LAYER.NAME' was missing in 
this context. -->
         <Title>Layer 2</Title>
         <ScaleHint min="4.9895273871448" max="49.8902848429637" />
       </Layer>

     </Layer>


We would also need to update the WARNING text to say "optional" instead 
of Mandatory.

If this is indeed what you were trying to achieve then please file a 
ticket and I'll make the required changes in MapServer 5.2.

Daniel
-- 
Daniel Morissette
http://www.mapgears.com/