Google Fit REST API "Unable to fetch DataSource for Dataset: xyz" - rest

Question

I'm testing out a few things in the OAuth 2.0 Playground and trying to get data in and out of Google Fit using their REST API
I have done this previously with success, I just didn't write down what I did.. now I've come back to make it a proper thing and can't get it working again.
I have access to Google Fit datasources via the dashboard. I can get a list of the dataSources that exist from:
https://www.googleapis.com/fitness/v1/users/me/dataSources
And that is successful. I have also created my own stream which has a single floating point weight value on it called
raw:com.google.weight:b6ac18c0:dten.sync
It already has data in it, I put it there last time I used it. I can select all that data by requesting a GET on the following
https://www.googleapis.com/fitness/v1/users/me/dataSources/raw:com.google.weight:b6ac18c0:dten.sync/datasets/0-1432193482000000000
It returns me all the data points I entered last time as JSON
I then try to PATCH the data adding my own data to the folliwng URL
https://www.googleapis.com/fitness/v1/users/me/dataSources/raw:com.google.weight:b6ac18c0:dten.sync/datasets/1432193482000000000-1432193482000000000
With this as a the request body
{
"minStartTimeNs": "1421912895000000000",
"maxEndTimeNs": "1432193482000000000",
"dataSourceId": "raw:com.google.weight:b6ac18c0:dten.sync",
"point": [
{
"startTimeNanos": "1421912895000000000",
"modifiedTimeMillis": "1421912895000",
"endTimeNanos": "1421912895000000000",
"value": [
{
"fPVal": 89.1
}
],
"dataTypeName": "com.google.weight"
}
]
}
But I get back
{
"error": {
"code": 400,
"message": "Unable to fetch DataSource for Dataset: raw:com.google.weight:b6ac18c0:dten.sync",
"errors": [
{
"domain": "global",
"message": "Unable to fetch DataSource for Dataset: raw:com.google.weight:b6ac18c0:dten.sync",
"reason": "invalidArgument"
}
]
}
}
I can't find any one referencing a similar anywhere soo I'm here
Also note if I miss spell my source it tells me off because they don't match the URL, if i include an empty list of data points I get the same error. I'm quite lost so I'm throwing it out there to see if anyone knows what that means
Thanks in advance
edit: i tried changing the hex code for my project's integer code and got an error about untrusted source. so i tried making a new test data source which works as expected. Slightly annoyed but guess I'll just start over..

Answer 1

OK I was stupid and didn't set up my own credentials in the OAuth settings in top right of the dashboard as it said to here. I forgot that bit -_- now I can access my own stream again and it shows my integer project id in the stream id not the hex one
https://developers.google.com/fit/rest/v1/get-started
Now I get invalid argument, but.. whatever >_<
edit 2:
invalid argument was because I have fPVal instead of fpVal and modifiedTimeMillis mills is not supposed to be submitted, obviously