Slack API Using \n for new lines does not work in chat.postMessage (golang)

Question

I'm using the Slack web API to post messages to a channel in Go. I'm trying to support multi-line messages in the text field. According to the documentation simply adding a \n should work but it's not working. When posting the \n appears in the text and there's no line break.

Here's the code I'm using:

func PostMessage(token, channelName, userName, text string) error {
    uv := url.Values{}
    uv.Add("token", token)
    uv.Add("channel", channelName)
    uv.Add("username", userName)
    uv.Add("text", text)

    resp, err := http.PostForm("https://slack.com/api/chat.postMessage", uv)
    if err != nil {
        return err
    }
    return nil
}

func main() {
    if err := PostMessage("xxxx", "#test-channel", "API", "This should be the first line\nThis should be the second line"); err != nil {
        panic(err)
    }
}

Solution 1

I figured out the issue. The sample I originally posted will actually work as intended. I simplified the original code which was a command line application where the text is a parameter passed as a CLI flag so it looked a little like this:

cliapp --text="one\ntwo"

The variable that held the value for this flag wasn't actually escaping the character so it was ACTUALLY:

"one\\ntwo"

I used a simple string replacement to fix the values:

text = strings.Replace(text, "\\n", "\n", -1)

Solution 2

I was using Java and i did

message.replace("\\n","\n")

and it worked.