[mapserver-dev] Error accessing Shape files w/noattributes

[Paul Ramsey]

Hrm. :) That's an experiment I haven't seen run. Can you open up a
lone .shp file with an Arc* tool?

On Fri, Oct 2, 2009 at 12:56 PM, Steve Lime <Steve.Lime at dnr.state.mn.us> wrote:
> I'll take care of it. Just to confirm, a shapefile with no attributes is valid according to the ESRI spec. correct?
>
> Steve
>
>>>> On 10/2/2009 at 1:53 PM, in message <4AC605C70200004F000144EC at jeckle>, "Jim
> Klassen" <Jim.Klassen at ci.stpaul.mn.us> wrote:
>> Sorry for the delay. I didn't see your response until now... anyway #3147
>>
>>>>> "Steve Lime" <Steve.Lime at dnr.state.mn.us> 09/29/09 10:10 AM >>>
>> 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/ )
>>> Making Saint Paul the Most Livable City in America
>>> _______________________________________________
>>> mapserver-dev mailing list
>>> mapserver-dev at lists.osgeo.org
>>> http://lists.osgeo.org/mailman/listinfo/mapserver-dev
>
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