[mapguide-internals] MapTips fail when properties have nullvalues?

[Ben Trumbore]

A workaround for this problem would be to create two layers from the
same data.  In one layer, set the feature filter to only show features
with a non-NULL value for the offending property, and use the maptip you
have been using.  For the other layer, set the filter to show features
where the property is NULL and choose a maptip that does not reference
the property.

	Ben

-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org
[mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Traian
Stanev
Sent: Wednesday, February 21, 2007 10:03 AM
To: MapGuide Internals Mail List
Subject: RE: [mapguide-internals] MapTips fail when properties have
nullvalues?

Oh I meant that one way I can think of to work around this right now is
to replace the values in the data source by empty string. I know that's
not the right thing to do.

The right thing to do is to call IsNull() somewhere in
RSMgFeatureReader::GetAsString(), which is used to convert property
values to strings for tooltips and selection.


Traian


-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org
[mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Paul
Spencer (External)
Sent: Wednesday, February 21, 2007 8:49 AM
To: MapGuide Internals Mail List
Subject: Re: [mapguide-internals] MapTips fail when properties have
nullvalues?

Traian, do you mean that the NULLs should be replaced by empty  
strings in the data source (not always feasible/desirable, esp if the  
data drives other apps that accomodate the NULL correctly)? or is  
there some way to do that in an expression?

Paul

On 20-Feb-07, at 2:39 PM, Traian Stanev wrote:

> I would say it's a bug in the expression evaluation code. Using empty
> string would likely work around the problem.
>
> Traian
>
>
> -----Original Message-----
> From: mapguide-internals-bounces at lists.osgeo.org
> [mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Jason
> Birch
> Sent: Tuesday, February 20, 2007 11:09 AM
> To: MapGuide Internals Mail List
> Subject: RE: [mapguide-internals] MapTips fail when properties have
> nullvalues?
>
> I can't say that I have much insight into why this is happening.
>
> This does mirror expected functionality in most DBMS systems, so it's
> not necessarily a bad thing, but these systems also provide  
> functions to
> work around the null values, such as NVL, ISNULL, etc...
>
> Jason
>
> -----Original Message-----
> From: mapguide-internals-bounces at lists.osgeo.org
> [mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Paul
> Spencer
> Sent: Tuesday, February 20, 2007 05:59
> To: MapGuide Internals Mail List
> Subject: [mapguide-internals] MapTips fail when properties have null
> values?
>
> Hi all ... I filed this as an issue in Trac but I haven't seen any
> comments on it :) Maptips fail to appear when the expression  
> references
> a property that is null for the current feature. Another feature that
> does not have null values in the properties will produce a map tip.
>
> Is this behaviour by design or a potential bug? Is there a way to work
> around null values in the data by replacing them with an empty string?
>
>
> Trac ticket is:
>
> http://mapguide.osgeo.org/trac/mapguide/ticket/3
>
> I'm not looking for resolution, just a quick answer on whether this is
> by design, a potential bug, or a configuration problem.
>
> Cheers
>
> Paul
>
> +-----------------------------------------------------------------+
> |Paul Spencer                          pspencer at dmsolutions.ca    |
> +-----------------------------------------------------------------+
> |Chief Technology Officer                                         |
> |DM Solutions Group Inc                http://www.dmsolutions.ca/ |
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+-----------------------------------------------------------------+
|Paul Spencer                          pspencer at dmsolutions.ca    |
+-----------------------------------------------------------------+
|Chief Technology Officer                                         |
|DM Solutions Group Inc                http://www.dmsolutions.ca/ |
+-----------------------------------------------------------------+




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