getting channel value from a webscoket client - go

Question

I'm running a websocket client and want to pass the response(s) from the client to a channel that i can work with in my main file. Currently, the channel just returns a nil value once and then nothing else. I seem to have an issue when passing a value to the channel. Any help? Here is what I've done so far
package main
import (
"context"
"fmt"
"kraken_client/stored_data"
"kraken_client/ws_client"
"os"
"os/signal"
"strings"
"sync"
"syscall"
)
func main() {
// check if in production or testing mode & find base curency
var testing bool = true
args := os.Args
isTesting(args, &testing, &stored_data.Base_currency)
// go routine handler
comms := make(chan os.Signal, 1)
signal.Notify(comms, os.Interrupt, syscall.SIGTERM)
ctx := context.Background()
ctx, cancel := context.WithCancel(ctx)
var wg sync.WaitGroup
// set ohlc interval and pairs
OHLCinterval := 5
pairs := []string{"BTC/" + stored_data.Base_currency, "EOS/" + stored_data.Base_currency}
// create ws connections
pubSocket, err := ws_client.ConnectToServer("public", testing)
if err != nil {
fmt.Println(err)
os.Exit(1)
}
// listen to websocket connections
ch := make(chan interface{})
wg.Add(1)
go pubSocket.PubListen(ctx, &wg, ch, testing)
// subscribe to a stream
pubSocket.SubscribeToOHLC(pairs, OHLCinterval)
go func() {
for c := range ch {
fmt.Println(c)
}
}()
<-comms
cancel()
wg.Wait()
defer close(ch)
}
Here is how the PubListen function works
func (socket *Socket) PubListen(ctx context.Context, wg *sync.WaitGroup, ch chan interface{}, testing bool) {
defer wg.Done()
defer socket.Close()
var res interface{}
socket.OnTextMessage = func(message string, socket Socket) {
//log.Println(message)
res = pubJsonDecoder(message, testing) // this function decodes the message and returns an interface
log.Println(res) // this is printing the correctly decoded value.
}
ch <- res
log.Println(res) // does not print a value
log.Println(ch) // does not print a value
<-ctx.Done()
log.Println("closing public socket")
return
}
What am I doing wrong?

Answer 1

The code in the question executes the statement ch <- res once from PubListen before the res is set by the OnTextMessage function.
To send a value to ch on each message, move the line ch <- res to the OnTextMessage function. That function is called once for each message.
func (socket *Socket) PubListen(ctx context.Context, wg *sync.WaitGroup, ch chan interface{}, testing bool) {
defer wg.Done()
defer socket.Close()
socket.OnTextMessage = func(message string, socket Socket) {
res := pubJsonDecoder(message, testing)
ch <- res
log.Println(res)
}
<-ctx.Done()
log.Println("closing public socket")
return
}