[Qgis-developer] Fields/attributes

Andreas Neumann a.neumann at carto.net
Fri Apr 26 00:03:24 PDT 2013


 The shape files should not constrain us with the column length anymore.

 Meanwhile, QGIS-Dev (master) even handles the column shortening and 
 conflict detection (if shortened columns collide because of the 
 shortening) correctly. This wasn't the case in older versions. Thanks to 
 whoever fixed that!

 Personally I would avoid characters outside of the [a-zA-Z_] range in 
 column names. Some formates may have troubles with these other 


 On Fri, 26 Apr 2013 08:41:45 +0200, Albin Blaschka wrote:
> Hello,
> sorry for intervening as an outsider...but maybe a tiny 
> contribution...
> Am 26.04.2013 02:39, schrieb Nathan Woodrow:
>> Hey Chris,
>> 1) I don't think there is any limit.  The name is just stored as a
>> QString so anything it supports QGIS should too.
> There are some limits in shapefiles concerning names in the attribute
> table, coming from the dbf - format. So, if at first the column names
> are e.g. longer than the eight characters allowed in dbf, and the 
> user
> stores the data later as a shapefile, in this way, a problem could
> maybe  arise, especially if the long names are similar at the
> beginning...
> regards,
> Albin
>> 2) I have noticed that too it is quite confusing at times.  To me 
>> fields
>> should refer to the column information, and attributes should refer 
>> to
>> the data it self, but that is not always the case in the API.
>> - Nathan
>> On Fri, Apr 26, 2013 at 10:33 AM, Chris Crook <ccrook at linz.govt.nz
>> <mailto:ccrook at linz.govt.nz>> wrote:
>>     Couple of questions with regard to QgsFeature fields and 
>> attributes:
>>     1) Are there any guidelines/constraints regarding field names.  
>> The
>>     delimited text provider can take names from the first line of a 
>> text
>>     file, and that can be very arbitrary.  I'm wondering if I should 
>> put
>>     more constraints on the names (maximum number of characters, 
>> valid
>>     character set, other...)
>>     2) It seems that fields get referred to in various places as 
>> fields
>>     and attributes in the API.  Is there any logic to this.  That is 
>> to
>>     say, where should I use the word "field", and where should I use 
>> the
>>     word "attribute"?
>>     Thanks
>>     Chris
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 Andreas Neumann
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