Handling failures in Init

[ZeroDeltaAlpha]

Hi I'm writing an app that does data fetching in the init func using http.

The data fetching func returns a Struct and a error type, in the case of a failure I send back an empty Struct and an err.

i run this using tea.Sequence, what is the best way to handle if err is not nil on init and take appropriate action ?

[bashbunni]

You can have a tea.Msg that is a struct holding your outputs from the data fetch. Then return that message. A tea.Msg is any data structure, you just need to specify in the function signature of your function as the return value, then you can use your function as a tea.Cmd

type HttpResponse struct {
    data []byte // change this to your struct if you want, or make your struct include the error
    err error
}

func FetchData(url string) tea.Msg {
    resp, err := http.Get("http://example.com/")
    if err != nil {
	    return HttpResponse{[]byte{}, err}
    }
    defer resp.Body.Close()
    body, err := io.ReadAll(resp.Body)
    return HttpResponse{body, err}
}

I hope that helps!

[ZeroDeltaAlpha]

Hi @bashbunni my issue is more like the following

func (m model) Init() tea.Cmd {
	cmds := make([]tea.Cmd, 0)
	cmds = append(cmds, List(fetchData(m.cfg)), tea.EnterAltScreen)
	return tea.Sequence(cmds...)
}

fetchData returns a list of items that could be empty and err. Is there a way i can surface this err from the Init function ?

Thanks

[bashbunni]

if you're wanting it to run asynchronously, you'll have to call those tea.Cmds like you're doing, then handle the errors in your Update when you receive the response from the function. You can return the response as a struct, then check for that kind of tea.Msg in your Update. Outside of that, you'd have to handle the error before you start your Bubble Tea program, but how I just described is how you handle errors within a Bubble Tea program.

Here's an example with ErrMsg:

bubbletea/examples/http/main.go

Line 52 in 6b77c8f

case errMsg:

I hope that helps!

[ZeroDeltaAlpha]

Awesome thanks @bashbunni I think i got that part nailed down, thank you for the help 😄