Find aritcle example for http://openmymind.net/Golangs-Error-Handling-Good-And-Bad/

gistfile1.go

func LoadArticle(res http.ResponseWriter, req *http.Request) {
  if article, err := FindArticleById(...)
  if err != nil {
    handleError(res, err)
    return
  }
  if article == nil {
   handleNotFound(res, err)
  }
}

func FindArticleById(id string) (*Article, error) {
  conn, err := db.Open()
  if err != nil {
    return nil, err
  }
  var ...
  err := conn.QueryRow("find_article_by_id", id).Scan(.....)
  if err != nil {
    return nil, err
  }
  return &Article{....}, nil
}

package article

var NotFound = errors.New("Article not found.")

func ShowArticle(w http.ResponseWriter, r *http.Request) {
    article, err := FindByID(r.FormValue("id"))
    switch {
    case err == NotFound:
        // show error page
        w.WriteHeader(http.StatusNotFound)
        fmt.Fprintf(w, "article wasn't found, maybe you should look at X instead")
        return
    case err != nil:
        log.Println(err.Error())
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }
    fmt.Fprintf(w, "%s", article)
}

func LoadByID(id string) (*Article, error) {
    conn, err := db.Open()
    if err != nil {
        return nil, err
    }

    var article Article
    err = conn.QueryRow("find_article_by_id", id).Scan(&article)
    if err != nil {
        // check here whether it actually is a not found error...
        return nil, NotFound
    }
    return &article, nil
}

With GeneralErrorHandling:

package article

var NotFound = errors.New("Not found.")

func ShowArticle(w http.ResponseWriter, r *http.Request) {  
    if article, err := FindByID(r.FormValue("id")); err == nil {
        GeneralErrorHandler(w, err)
        return
    }
    fmt.Fprintf(w, "%s", article)
}

func LoadByID(id string) (*Article, error) {
    conn, err := db.Open()
    if err != nil {
        return nil, err
    }

    var article Article
    err = conn.QueryRow("find_article_by_id", id).Scan(&article)
    if err != nil {
        // check here whether it actually is a not found error...
        return nil, NotFound
    }
    return &article, nil
}

With panicking, there should be some sort of recovery happening at the upper level...

package article

var NotFound = errors.New("Not found.")

func ShowArticle(w http.ResponseWriter, r *http.Request) {  
    article := FindByID(r.FormValue("id"))
    fmt.Fprintf(w, "%s", article)
}

func LoadByID(id string) *Article {
    conn, err := db.Open()
    if err != nil {
        panic(err)
    }

    var article Article
    err = conn.QueryRow("find_article_by_id", id).Scan(&article)
    if err != nil {
        // check here whether it actually is a not found error...
        panic(NotFound)
    }
    return &article
}