Git Log as JSON in Go

For reasons I wanted git log to be parsed in Go and it looks like the easiest way to do that is to output it as JSON and parse into Go structs.

First we need to define the format for the JSON (borrowed from here):

var GITFORMAT string = `--pretty=format:{
  "commit": "%H",
  "parent": "%P",
  "refs": "%D",
  "subject": "%s",
  "author": { "name": "%aN", "email": "%aE", "date": "%ad" },
  "commiter": { "name": "%cN", "email": "%cE", "date": "%cd" }
 },`

Then define the structs:

type GitPerson struct {
 Name  string     `json:"name"`
 Email string     `json:"email"`
 Date  *time.Time `json:"date"`
}
type GitCommit struct {
 Commit  string `json:"commit"`
 Parent  string `json:"parent"`
 Refs    string `json:"refs"`
 Subject string `json:"subject"`
 Author   GitPerson `json:"author"`
 Commiter GitPerson `json:"commiter"`
}

The function will then run git log and Unmarshal the result:

func gitLog() ([]GitCommit, error) {
 args := []string{
  "log", 
  "--date=iso-strict", 
  "--first-parent", 
  GITFORMAT,
 }
 cmd := exec.Command("git", args...)
 out, _ := cmd.Output()
 
 logOut := string(out)
 logOut = logOut[:len(logOut)-1] // Remove the last ","
 logOut = fmt.Sprintf("[%s]", logOut) // Add []
 
 gitCommitList := []GitCommit{}
 json.Unmarshal([]byte(logOut), &gitCommitList)
 return gitCommitList, nil
}

--date=iso-strict makes sure that the dates that are outputted are parsable by Go.

Hopefully if you find a reason to need git log in Go this might help :)