[Qgis-developer] morph delimited-text-provider to generic table-provider?

[Raymond Nijssen]

Hi Andreas,

I'd just like to see a way to create a new layer from any (attribute)
table in QGIS. So, even a point shapefile containing a wkt column with
polygons or a database table containing x and y field or an opened xls
sheet containing json somewhere.

My suggestion:

- To strip the geometry stuff from the CSV importer.
- Have a new tool to create a geometry layer from any QGIS table.

I think this would be easy to understand for users, although some would
need both tools to import a csv with geometry.

Regards,
Raymond

> Hi,
>
> I would welcome an "easier" way to open Point or WKT data from formats
> that do not store geometries natively, as you propose. Thanks for
> bringing it to the table, Raymond and Richard!
>
> My suggestion would be to enhance the existing OGR "Add vector layer"
> dialog with an option to choose columns to be used for geometry
> creation. This way we don't have to "misuse" the delimited text layer
> loader for other formats and the user could open the data all in one
> step, without the need for postprocessing. OGR VRT provides all we need
> to create geometries from columns - see http://www.gdal.org/drv_vrt.html
>
>
> The drawback is that it would work only for OGR formats, not for all the
> other databases. But I would assume that people using databases are
> skilled enough to be able to use QGIS virtual layers, views, etc. to
> build geometries from their databases.
>
> Greetings,
> Andreas
>
> On 2016-07-09 11:00, Richard Duivenvoorde wrote:
>
>> Hi Devs,
>>
>> Raymond Nijssen had an (I think) intriguing idea:
>>
>> QGIS can open different types of table-data: dbf, excel etc etc
>>
>> But if the excel contains an x,y,wkt column, you have to save it to
>> csv/tsv first, to be able to use the delimited-text-provider to open it
>> as a layer.
>>
>> His idea: can't we use the delimited-text-provider for all tables that
>> are open in QGIS immediately?
>>
>> Had a look into the code
>>
>> https://github.com/qgis/QGIS/blob/master/src/providers/delimitedtext/qgsdelimitedtextfile.cpp#L583
>>
>> which 'just' looks like a QTextStream:
>>
>> https://github.com/qgis/QGIS/blob/master/src/providers/delimitedtext/qgsdelimitedtextfile.h#L352
>>
>> And according to this:
>> https://forum.qt.io/topic/63310/how-to-save-a-treeview-as-csv-file-in-qt
>>
>> It is easy to create a textstream from QModel (in which we have the data
>> I think???)...
>>
>> So Question:
>> - (to devs): would this indeed be doable/easy?
>> - (to UI's): should the Delimited Text File dialog be updated then (or
>> only with a 'open excisting table button'?
>> - should we rename the provider to 'table' provider.
>>
>> Comments/Opinions?
>>
>> Regards,
>>
>> Richard Duivenvoorde
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