Why don't I see fmt logs in my terminal when running go app locally?

Question

I'm trying to debug my golang app. Currently, I have an API request that isn't working which has this line of code: fmt.Errorf("Object(%q).CopierFrom(%q).Run: %v", dstName, object, err)

How can I view the output of this error log? And if it's not possible what are some other ways to debug in go? (runtime invocation would be nice)

Answer 1

fmt.Errorf() creates an error object. but not print.doc

If you're just trying to print the message to stdout: run

package main

import (
    "fmt"
)

func main() {
    const name, id = "bueller", 17
    err := fmt.Errorf("user %q (id %d) not found", name, id)
    fmt.Println(err.Error())

}

out:

user "bueller" (id 17) not found

if you want debug golang code, I recommend use log packages for example: zerolog

package main

import (
    "errors"

    "github.com/rs/zerolog"
    "github.com/rs/zerolog/log"
)

func main() {
    // UNIX Time is faster and smaller than most timestamps
    zerolog.TimeFieldFormat = zerolog.TimeFormatUnix

    err := errors.New("seems we have an error here")
    log.Error().Err(err).Msg("this is an error")
}

out:

{"level":"error","error":"seems we have an error here","time":1640795128,"message":"this is an error"}