The discussion so far has been predominantly about phpfina (fixed interval) feeds rather than phptimeseries (variable interval). your “Zon Vandaag KwH” feed is phptimeseries.
Essentially the same applies, you cannot insert data prior to the feeds start time and with phptimeseries you cannot even insert new datapoints after the feed starttime if they are before the last post time because the datapoints are timestamp and value pairs, written to file in the order they arrive and cannot be moved without rewriting the whole file from that inserted timestamp to the end of the file to make room. So in short you can only append new data after the last datapoint or edit an existing datapoint.
But the solution is also similar, you can create a new “daily” phptimeseries variable interval feed without initiating it and then use a feed api to write your data to it. using something like
https://myserver/emoncms/feed/create.json?name="Zon Vandaag KwH"&datatype=2&engine=2
you should get a response like
{"success":true,"feedid":1234,"result":true}
where “1234” is the feedid allocated by emoncms, you will need that feedid to post your data, then set up a script to loop through all your old data (presorted into date order!!) and post using this url, changing the time and value each time.
https://myserver/emoncms/feed/insert.json?id=1234&time=1414579200&value=0.4&apikey=abc123
You will need to add your write apikey for the script to work as it will not matter if you are logged in via a browser.
It is essential the data you post is in chronological order, there is no inserting or backfilling, you will need to start again if you miss one or get the order wrong.
Once you have the old data in place you can use a feed api to export the current feed data and re-post it in exactly the same way as you did your old data, to the same feed.
You can then swap them over in your input processing and dashboards etc and delete the old feed if you are happy with it. You may see a slight error in the value for the day you make the switch, but it should be minimal (depending on time of day and time taken) and that days value can be edited if needed.
