[Qgis-user] Label missing in Weekly

[Nathan Woodrow]

Hey,

QgsExpression doesn't treat NULL and Empty string as the same thing. Which
is why we don't auto convert.  To convert nulls in a field you should use
the coalesce("Areatype",'')

See http://hub.qgis.org/issues/8369

- Nathan


On Fri, Aug 2, 2013 at 7:35 AM, Larry Shaffer <larrys at dakotacarto.com>wrote:

> Hi Lene,
>
> On Thu, Aug 1, 2013 at 2:25 PM, Lene Fischer <lfi at life.ku.dk> wrote:
>
>> Hi Goyo
>> The geometries is OK.
>> I have a combined label Ex.
>> Areatype || '\n' ||  $Area   || ' m2'
>> Now I found that if one field is empty (Even if there is NULL in the
>> field), then the entire label will not be displayed.
>>
>
> When the expression-based label text was introduced, NULL values
> supposedly where just converted to empty strings [0], i.e. if Areatype was
> NULL, one would expect at least 'm2' to be present in the label.
>
> Try enclosing your field name Areatype in double quotes. Also, try without
> the $Area function, but still with the || concatenation. If the label still
> does not contain any text, then it is probably a bug in how QgsExpression
> handles NULL values from the data provider. If so, please create an issue
> ticket [1]. Include a test project file, and try to list reproducible
> steps, if you can.
>
> [0]
> http://osgeo-org.1560.x6.nabble.com/Expression-based-labeling-tp4100735p4100736.html
> [1] http://hub.qgis.org/projects/quantum-gis/issues
>
> Regards,
>
> Larry
>
>
>> Regards
>> Lene
>>
>>
>>
>> ________________________________________
>> Fra: Goyo [goyodiaz at gmail.com]
>> Sendt: 1. august 2013 20:40
>> Til: Lene Fischer
>> Cc: qgis-user at lists.osgeo.org
>> Emne: Re: [Qgis-user] Label missing in Weekly
>>
>> 2013/8/1 Lene Fischer <lfi at life.ku.dk>:
>> > Hello
>> > I´m using the new labelfunction - it is great!! - but som of the labels
>> are
>> > missing. I have a small project with only 9 polygons, but only 7 labels
>> is
>> > visible.
>> > I´ve tried:
>> >
>> > Settings to "View all labels in all layers"
>> > change attributefield and size
>> >
>> > Same result. Any suggestions?
>> > Regards
>> > Lene Fischer
>>
>> You might have invalid geometries. They are not labelled IIRC.
>>
>> Goyo
>>
>>
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>>
>
>
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