HTTP API Request with Node-RED

Application Development
1

Hello,
According to the documentation of the application manager api we should be getting output for this API ( GET /applications/{app_id}/devices/{dev_id}) if the input is of the form

{
  "app_id": "some-app-id",
  "dev_id": "some-dev-id"
}

I passed this as msg.payload to the HTTP request node (GET) from the url http://.thethings.network:8084, but I don’t receive a json object.

2

What is the response code/msg?
How do you manage auth?

3

I am trying to understand how to manage authentication, currently the response code says that no json string detected. 404 is the code (it is 200 for successful)

4

If anybody knows anything that can help me kickstart the process please do help.

5

404 means that your url is wrong. So you don’t have a json because you are not calling an existing ressource. Without auth, but with an existing ressource, you will receive a 403 or 401.

What is the full url you are using?

7

The url from which i am requesting data is:

http://eu.thethings.network:8084

This is the Snapshot of Node red:
image

8

You need to call the endpoint, not the root of the API.
Example: http://eu.thethings.network:8084/applications/45
Will answer:
{“error”:“Metadata not valid: neither token nor key present”,“code”:2,“message”:“Metadata not valid: neither token nor key present”} (try in your browser).
In your case, you have to call: http://eu.thethings.network:8084/applications/{app_id}/devices/{dev_id}

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9

That’s incomplete. You may want to try without Node-RED first. The following works for me, on a Mac. Just for readability, a trailing backslash \ indicates the command continues on the next line; I think that’s a forward slash / on Windows. The --get and --url are optional, and --header is the same as -H:

  • To get all devices in application arjanvanb-1:

    curl \
  --get \
  --header 'Authorization: Key ttn-account-v2.m2xb7<redacted>I3RqU' \
  --url http://eu.thethings.network:8084/applications/arjanvanb-1/devices

    Beware that the URL should not end with a slash; using [...]/devices/ will throw Invalid Device Identifier: DevID not valid: can not be empty.

  • To get details of a single device, like arjanvanb-heltec-4 in application arjanvanb-1:

    curl \
  --get \
  --header 'Authorization: Key ttn-account-v2.m2xb7<redacted>I3RqU' \
  --url http://eu.thethings.network:8084/applications/arjanvanb-1/devices/arjanvanb-heltec-4

So, you’ll need something in Node-RED to programmatically expand the URL to include the application id and device id in the URL. See, e.g., Handle url parameters in an HTTP endpoint : Node-RED See, e.g., Set the URL of a request using a template : Node-RED or Set the URL of a request : Node-RED (and Node-RED Cookbook : Node-RED in general).

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10

For those with allergies at the CLI, Postman is great to begin and understand how an API works.

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