Things I Learned: Querying Datasette using URLs

I never expected the Rockmite ham radio to get anywhere close to working all 50 states. Consequently, the QSO database for the rig doesn't include state or county columns. Diaze—my12 year-old partner in crime—and I set out to fill in the missing data this weekend while she learned to program Python. I'll discuss the complete project soon. While we were working, I learned that I could query Datasette via URL.

My SQL is a bit rusty. That pushed me towards controlling Datasette from the outside, and frankly, that made more sense and was more on theme for learning about sending URL requests and using the returned json text—a topic Diaze is working on learning this week. It was also a more complete solution that didn't require moving data from a web page into a Python script.

I noticed that when I ran a Python query, and then pressed the link for either CSV or json output, the URL of the output reflected the original query. Here's the query for outputting all QSOs from the database:

http://127.0.0.1:8001/rm_toucans_23_10_07.json?sql=select+Spotter%2C+rx_lng%2C+rx_lat+from+rm_rnb_history_pres+where+%22dB%22+%3E+%3Ap0+order+by+rowid&p0=99

It seemed simple enough to use Python requests to feed the results from a query of one database—QSOs—as parameters for a query to another database—the Datasette counties example database. And I did exactly that. The URLs are long due to URL escaping, so I won't include them here, but you can see them in the github repo.

The thing I learned is that by rewriting the URL in a loop I could add the latitude and longitude for each QSO—something we did store in the original database—and retrieve the state and county for each call. Here's the tail-end of the modified counties URL:

&longitude='+str(lng)+'&latitude='+str(lat))

The query results are returned in the "rows" member of a json object

for localities in z["rows"]:

And here is what the results look like for now:

The next step will be to add them to an edited version of the database—within the script of course—rm_rnb_history_pres.csv.

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