[mapserver-dev] Error accessing Shape files w/no attributes

[Steve Lime]

Jim: Create a quick ticket and I'll take care of applying your patch tonite.

Steve

>>> On 9/28/2009 at 2:38 PM, in message <4AC0CA720200004F000142A1 at jeckle>, "Jim
Klassen" <Jim.Klassen at ci.stpaul.mn.us> wrote:
> When I try to access a layer that points to a shape file with no attributes I 
> get the following error...
> 
> msDrawMap(): Image handling error. Failed to draw layer named 'CITYOUTLINE'. 
> msGetDBFItems(): DBASE file error. File contains no data.
> 
> It looks like this is related to a change introduced with the improved 
> algorithm in msLayerWhichItems() in maplayer.c. The problem seems to be how 
> lines 385 and 386 are interacting with msDBFGetItems/msShapeFileLayerGetItems 
> in that msShapeFileLayerGetItems is returning MS_FAILURE because 
> msDBFGetItems found no items and thus calls msSetError and returns NULL. The 
> line maplayer.c:386 then causes msLayerWhichItems to fail before line 388 can 
> say this is an expected condition.
> 
> 385  rv = msLayerGetItems(layer);
> 386  if(rv != MS_SUCCESS) return rv;
> 387
> 388  if(layer->numitems == 0) return MS_SUCCESS; /* nothing to do but not an 
> error */
> 
> The following are the changes I made to mapshape.c (to return MS_SUCCESS) 
> and to mapxbase.c to not set an error that isn't an error. The change to 
> mapxbase.c may cause issues with tileindexed layers with no attributes in the 
> tileindex shapefile failing without an error message. This depends on what 
> the correct behavior is in another place in msTiledSHPLayerGetItems. I think 
> this is for the tileindex not the actual data shapes, and the tileindex does 
> require at least one attribute. If this is true and the mapxbase.c change is 
> kept, an error probably needs to be set in msTiledSHPLayerGetItems if there 
> are no items.  
> 
> Index: mapshape.c
> ===================================================================
> --- mapshape.c	(revision 9354)
> +++ mapshape.c	(working copy)
> @@ -2579,6 +2579,7 @@
>  
>    layer->numitems = msDBFGetFieldCount(shpfile->hDBF);
>    layer->items = msDBFGetItems(shpfile->hDBF);    
> +  if(layer->numitems == 0) return MS_SUCCESS; /* No items is a valid case */
>    if(!layer->items) return MS_FAILURE;
>  
>    return msLayerInitItemInfo(layer);
> Index: mapxbase.c
> ===================================================================
> --- mapxbase.c	(revision 9354)
> +++ mapxbase.c	(working copy)
> @@ -824,7 +824,7 @@
>    char fName[32];
>  
>    if((nFields = msDBFGetFieldCount(dbffile)) == 0) {
> -    msSetError(MS_DBFERR, "File contains no data.", "msGetDBFItems()");
> +    /*msSetError(MS_DBFERR, "File contains no data.", "msGetDBFItems()");*/
>      return(NULL);
>    }
> 
> 
> James Klassen
> Office of Technology and Communications
> 15 West Kellogg Blvd
> Saint Paul, MN 55102
> P: 651-329-8741
> USNG: 15TVK92577674
> ( http://www.stpaul.gov/ )
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