[Qgis-user] [QGIS-Developer] Refresh layer at interval

Richard Duivenvoorde rdmailings at duif.net
Mon Nov 2 03:25:14 PST 2020


Ah, and to reproduce, I created a temporary(!) service:

https://duif.net/geotest/points.geojson

which gives you one random point on the world every time you refresh

Regards,

Richard


On 11/2/20 12:23 PM, Richard Duivenvoorde wrote:
> I think you hit an old issue:
> 
> https://github.com/qgis/QGIS/issues/28282
> and
> https://github.com/qgis/QGIS/issues/28744
> 
> Not sure if I can tackle it, but I can give it a try.
> If a core-dev has a clue, please let me know...
> 
> I think this should work, as this makes it supereasy to have a 'moving map'..
> 
> Regards,
> 
> Richard Duivenvoorde
> 
> 
> On 11/1/20 9:24 PM, nagyrobi_r at yahoo.com wrote:
>>
>>     Hi All!
>>
>>     I am trying to understand the behavior of Layer->Render-> Refresh layer at interval in QGIS
>>
>>      1. I sat up a flask rest api which serves a geojson.
>>      2. I added the geojson to QGIS via Add Layer-> 
>>          1. a. Protocol HTTP/cloud/etc 
>>          2. b. Type: HTTP 
>>          3. c.URI: localhost/points.geojson The points are represented on the map correctly
>>      3. I changed the layer->Properties->Rendering-> Refresh layer at interval (5 sec)
>>
>>     I would have expected that there would be a call every 5 seconds towards the server and the map data would be updated accordingly. But the layer does not get refreshed. I don't see any changes neither when I remove a point from the json file on my local drive, nor if I change an attribute. If I press F5 then the canvas refreshes and it automatically loads the new data and I can see the changes. Is this the behavior that is wanted or am I misunderstanding the function of this tool? It seems like the data is cached somewhere?
>>
>>     |from flask import Flask from flask_restful import Api, Resource import json app = Flask(__name__) api = Api(app) class point(Resource): def get(self): with open('C:/points/venv/src/points.geojson') as json_file: data = json.load(json_file) return data api.add_resource(point,"/points.geojson") if __name__=="__main__": app.run(debug=True)|
>>
>>     |Robert Nagy|
>>
>>
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