[Qgis-user] automatically reload (csv) file
Dr. Marco Lechner
mlechner at bfs.de
Fri Sep 18 04:23:00 PDT 2015
Hi,
just for my better understanding: is the "Add delimited text layer" at
its end using libogr anyway? We use the Option - I just did not know
about the "watch file" Option.
Does
QgsMapLayerRegistry.instance().mapLayer(u'mylayer201509181234').triggerRepaint()
reread the features of any filebased datasource (e.g. shape) as well? in
that case it was very simple to create a watch-it plugin for any
file-based vector-(and raster?)-datasource.
Marco
Am 18.09.2015 um 11:57 schrieb Andreas Neumann:
> Hi Delazj,
>
> Yes - I was assuming that people would use the "Add delimited text layer
> tool". Sorry - I forgot to mention that. It is more flexible and easier
> to use than the "Add vector layer" dialogue.
>
> About CSV, joins and updates: have you checked the cache vs. uncached
> option for your joins?
>
> Andreas
>
> On 18.09.2015 11:47, DelazJ wrote:
>> Hi,
>> Andreas, unless you add the csv file with "Add delimited text layer"
>> tool, I'm afraid there's not a "watch file" option available.
>>
>> I just add a csv file to a qgis project with "add a vector layer"
>> tool. I open the same csv in a text editor and change some values.
>> While reopening the csv file attribute table in QGIS, values were
>> already uptodate. I've done nothing special. So I'm not sure if QGIS
>> requiers a particular action to sync data.
>> But what seems buggy is that even if the csv file attribue table is
>> updated in QGIS, if this csv was joined to a shapefile, the changes
>> won't be applied in the shapefile's attribute table. Can someone confirm?
>> I can't get changes with the "Refresh" button.
>>
>> Tested with qgis ltr 2.8.3
>>
>>
>> 2015-09-18 10:38 GMT+02:00 Andreas Neumann
>> <<mailto:a.neumann at carto.net>a.neumann at carto.net>:
>>
>> Hi Marco,
>>
>> If you have the "watch file" option of your CSV file active it
>> will reread data when file content changes and when your redraw
>> your map (either through navigation or redraw button).
>>
>> I guess you could also write a small Python script if you want to
>> automatically trigger an update at a given interval. Maybe there
>> is already a plugin available - I did not look.
>>
>> Andreas
>>
>>
>> On 18.09.2015 10:15, Dr. Marco Lechner wrote:
>>> Hi Nicola,
>>>
>>> I guess this will only redraw the features in the mapcanvas, but not
>>> necessarily read the datasource file, but I'm not sure about this.
>>>
>>> Marco
>>>
>>> Am 18.09.2015 um 10:02 schrieb Nicola Poles:
>>>> To reload a CSV file you can press the Refresh button on the toolbar or
>>>> press the "F5" key
>>>>
>>>> Nicola
>>>>
>>>> On Fri, Sep 18, 2015 at 9:16 AM, Dr. Marco Lechner <mlechner at bfs.de <mailto:mlechner at bfs.de>
>>>> <mailto:mlechner at bfs.de> <mailto:mlechner at bfs.de>> wrote:
>>>>
>>>> Hi,
>>>>
>>>> how (often) does QGIS read features from a file (like csv or shape -
>>>> differences?)? I realize I do not really know how the datasource - qgis-
>>>> communication goes.
>>>>
>>>> Imaine you have a csv or shape file that is loaded into QGIS but is
>>>> automatically replaced from time to time (or lets say externally
>>>> edited). Using a database- instead of file-based approach is better for
>>>> sure, but still it is not clear when / how often (on which events) QGIS
>>>> requests features from the datasources.
>>>>
>>>> As an idea in mind I see, the nice Sync-Plugin
>>>> (https://plugins.qgis.org/plugins/SyncQGISWithDir/) can monitor folders
>>>> and notify the user if a new layer is available in a folder (well it
>>>> does not take care of a changed layer (new timestamp of file, but adding
>>>> this functionality should not be such a big thing). The user could also
>>>> be notified when a layers file changed.
>>>>
>>>> But I'm not sure what was the best way to implement the (re)loading of
>>>> an already loaded layer. Do I have to drop the layer and reload it
>>>> (including keeping the style) or is there a more efficient way?
>>>>
>>>> Marco
>>>>
>>>> --
>>>> Dr. Marco Lechner
>>>> Bundesamt fuer Strahlenschutz / Federal Office for Radiation Protection
>>>> SW2.1 Koordination Notfallschutzsysteme / Coordination Emergency Systems
>>>> Rosastrasse 9 | D-79098 Freiburg | Germany
>>>> mlechner at bfs.de <mailto:mlechner at bfs.de> <mailto:mlechner at bfs.de> <mailto:mlechner at bfs.de> | +49 (0)3018 333 6724 <tel:%2B49%20%280%293018%20333%206724>
>>>> <tel:%2B49%20%280%293018%20333%206724> | www.bfs.de <http://www.bfs.de> <http://www.bfs.de> <http://www.bfs.de>
>>>>
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