sending a JSON string

[Douglas Ruisaard]

I'll start by apologizing for my abysmal familiarity with HTTP, JSON, and URL's ... I'm hoping someone will have pity and give me a hand!

I am trying to send a "command" to a ThingSpeak channel, which is very successfully receiving data from a simple little ESP8266 module.  Periodically, I need to clear the data from this channel.  I want to do so from LC.. NOT the ESP8266.  I just can't seem to "coordinate" the instructions from the ThingSpeak site to DELETE this data (not the channel, just the data within) with an LC function / code.

The link to the ThingSpeak page I am referring to is: 
https://www.mathworks.com/help/thingspeak/clearchannel.html?searchHighlight=delete%20channel%20data&s_tid=doc_srchtitle#d120e16923

but in essence, I interpret the content to assert the following:

Access the following URL: "https://api.thingspeak.com/channels/564256/feeds.json" where "564256" is the channel I wish to clear.

Send the JSON "command": "DELETE https://api.thingspeak.com/channels/564256/feeds.json
			       api_key= EQKTUQQKVH83D1RE" 

				where "EQKTUQQKVH83D1RE" is my account api-key for writing to the ThingSpeak channel

if successful, ThingSpeak responds with: "[]" ... an empty JSON array


In LC, I've tried the following (and several variations):

on mouseUp
   put empty into field "Output"   
   put "https://api.thingspeak.com/channels/564256/feeds.json" into tUrl
   put "DELETE https://api.thingspeak.com/channels/564256/feeds.xml" & return & "api_key=EQKTUQQKVH83D1RE" into JsonCmd
   
   -- Send a HTTP DELETE request
   put tsNetCustomSync(tUrl, JsonCmd, tHeader, tResponseHeaders, tResult, tBytes) into tData
   
   -- If this is not the case, we will inform the user
   put tResult into field "Output"
   
end mouseUp

I get a tResult of 0 (zero) ... but the data is NOT cleared.  

I have also tried the following:

on mouseUp
     put empty into field "Output"
     put "https://api.thingspeak.com/channels/564256/feeds.json?api_key=EQKTUQQKVH83D1RE" into tUrl 
     put "DELETE https://api.thingspeak.com/channels/564256/feeds.json" & return & "api_key=EQKTUQQKVH83D1RE" into tMessage["text"]
     
     put ArrayToJSON(tMessage) into tMessage
     
     set the httpHeaders to "Content-type: application/json"
     
     post tMessage to url tUrl
     
     put it into field "Output"

end mouseUp

But that only "creates" a new entry in the channel with all of the data fields empty.

I'm sure it's the way in which I am trying to send the "DELETE" command but I just can't see how to do it correctly.

I'd be grateful for any assistance.


Douglas Ruisaard
Trilogy Software
(250) 573-3935