Having issues with axios getting and returning data in my custom node

General
1

I am trying to use axios to call a URL and return its data. That part is working, but the ordering is not working when used as a function call. I am sure it's something simple, but I am not used to JavaScript.

The code below has two node.warn parts so that I can see what is being returned.
The one in the function node.warn(["Finally", r, e]) shows the correct data, the one after the function call node.warn(["HTTP", httpReq]); is returned first, and shows httpReq as being undefined. It's like the code is not waiting for the function call to execute.

function httpRequest(method, url, headers) {
    var r = null;
    var e = null;

    switch (method) {
        case "GET": {
            axios.get(url)
                .then(response => {
                    r = response.data;
                })
                .catch(error => {
                    e = error;
                })
                .finally(() => {
                    node.warn(["Finally", r, e])
                    return [r, e];
                })
            break;
        }

        case "POST": {
            node.warn("POST");
            break;
        }

        default: {
            raiseError("No method defined", msg);
            break;
        }
    }
}

With the function call of

this.on('input', function(msg, send, done) {
    if ((this.action != "Log Off") && (!flow.sid || flow.sid == undefined)) {
        var url = "http://www.example.com"
        var httpReq = httpRequest("GET", url);
        node.warn(["HTTP", httpReq]);
    }
    done();
})
2

Just a question first - many people who are new to Node Red bring their "old way" of doing things - wondering have you looked at the HTTP request node to do this for you ? i.e. move your code into the visual paradigm or is there a reason this will not work for you ?

Craig

3

I have a working subflow performing one specific API call but want to expand the functionality to cover more API calls. The only way to do this without it being a massively huge flow is by creating a custom node

4

Aaah right - fair enough i guess - i personally would still go with inidividual http nodes unless you are talking 100's of api calls

Craig

5

you are right .. because axios is async it executes in your httpRequest function and then it moves along to the next thing .. which is the break ? it doesnt return anything at that point

maybe it would be better if you return the axios call (which is a Promise)

function httpRequest(method, url, headers) {

      switch (method) {
        case "GET": {
          return axios.get(url);
        }

        case "POST": {
          node.warn("POST");
        }

        default: {
          raiseError("No method defined", msg);
          break;
        }
      }
    }

... and then use await and a try catch on the input callback (which needs to be async also)

   this.on("input", async function (msg, send, done) {
      var url = "http://www.example.com";

      try {
        var response = await httpRequest("GET", url);
        var httpReq = response.data;
        node.send({ payload: httpReq });
      } catch (err) {
        node.warn(err);
      }
      done();
    });
6

This is the nature of the async beast.

Add a callback argument to your httpRequest function & call the callback inside the then and catch (get rid of the two variables & the finally)

7

Thanks, I'll have a play

8

This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.