New golang package to reduce code duplication in APIs

#go #package #productivity

Hi Golang developers!

I just released a new package that will help you develop APIs in go.

Look at this code :

func (a *API) handleChangePassword(w http.ResponseWriter, r *http.Request) {
    vars := mux.Vars(r)
    userID := vars["userID"]

    requestBody, err := ioutil.ReadAll(r.Body)
    if err != nil {
        errorResponse(w, http.StatusInternalServerError, "", err) // <-- your custom error logic that you write for 
                                                                  //      each project
        return
    }

    var requestData ChangePasswordRequest
    if err := json.Unmarshal(requestBody, &requestData); err != nil {
        errorResponse(w, http.StatusInternalServerError, "", err)
        return
    }

    if err = requestData.IsValid(); err != nil {
        errorResponse(w, http.StatusBadRequest, err.Error(), err)
        return
    }

    if err = a.app().ChangePassword(userID, requestData.OldPassword, requestData.NewPassword); err != nil {
        errorResponse(w, http.StatusBadRequest, err.Error(), err)
        return
    }

    jsonStringResponse(w, http.StatusOK, "{}") // <-- your custom code that your are write for each project
}

This is often the code I see on Go projects. There is nothing wrong with writing this because it is very efficient and declarative.

But sometimes we would still like to focus a little more on what matters: business logic.

The version with KCD of this code now:

type ChangePasswordRequest struct {
    UserID string `path:"userID"`
    // ...
}

func (c *ChangePasswordRequest) Validate() error {
    // ...
}

func (a *API) handleChangePassword(request *ChangePasswordRequest) error {
    if err = a.app().ChangePassword(request.UserID, request.OldPassword, request.NewPassword); err != nil {
        return errors.Wrap(err, "unable to change password").WithKind(errors.KindInvalidArgument)
    }

    return nil
}