Set nested fields in Golang with the Logrus?

I'm using github.com/sirupsen/logrus to make a logger. This simplifies how fields are being initiated in the logger (straightforward from docs):

package main

import "github.com/sirupsen/logrus"

func main() {
	logFields := logrus.Fields{
		"details": logrus.Fields{
			"app_name":    "Some name",
			"app_version": "Some version",
		},
	}

	logger := logrus.New()
	logger.WithFields(logFields)
}

The library seems to allow to add fields with method WithFields only at top level (as in the last line).

But because my API has many steps, I need to add nested fields under details with every step (to accumulate log data), then output it all together in the end.

How can I add these fields?

logrus.Fields is just map[string]interface{}, so you can nest all data in every steps into a struct like

type Details struct {
    Step1 string `json:"step1"`
    Step2 string `json:"step2"`
    Step3 string `json:"step3"`
}

and finally logger.WithFields(logFields).Debugln("some debug info")

Another method, you can create multiple variables to save data from every step, for example

var step1data = "step1"
var step2data = "step2"

and finally

logger.WithFields(logrus.Fields{
        "details": logrus.Fields{
            "step1": step1data,
            "step2": step2data,
        },
    }).Debugln("some debug info")`

</details>