Implements our own errors

3 files changed, 46 insertions, 12 deletions

diff --git a/cmd/api/datamaps.go b/cmd/api/datamaps.go
index c58d811..10dfa38 100644
--- a/cmd/api/datamaps.go
+++ b/cmd/api/datamaps.go
@@ -29,8 +29,7 @@ func (app *application) createDatamapHandler(w http.ResponseWriter, r *http.Requ
 	// Parse the multipart form
 	err := r.ParseMultipartForm(10 << 20) // 10Mb max
 	if err != nil {
-		http.Error(w, err.Error(), http.StatusBadRequest)
-		return
+		app.serverErrorResponse(w, r, err)
 	}
 
 	// Get form values
@@ -77,8 +76,7 @@ func (app *application) createDatamapHandler(w http.ResponseWriter, r *http.Requ
 	err = app.writeJSONPretty(w, http.StatusOK, envelope{"datamap": dm}, nil)
 	if err != nil {
 		app.logger.Debug("writing out csv", "err", err)
-		http.Error(w, "Cannot write output from parsed CSV", http.StatusInternalServerError)
-		return
+		app.serverErrorResponse(w, r, err)
 	}
 
 	// fmt.Fprintf(w, "file successfully uploaded")
@@ -89,8 +87,7 @@ func (app *application) showDatamapHandler(w http.ResponseWriter, r *http.Reques
 	app.logger.Info("the id requested", "id", id)
 	id_int, err := strconv.ParseInt(id, 10, 64)
 	if err != nil || id_int < 1 {
-		http.NotFound(w, r)
-		return
+		app.notFoundResponse(w, r)
 	}
 	fmt.Fprintf(w, "show the details for datamap %d\n", id_int)
 }
diff --git a/cmd/api/errors.go b/cmd/api/errors.go
index 77833f3..2a40bad 100644
--- a/cmd/api/errors.go
+++ b/cmd/api/errors.go
@@ -1,7 +1,46 @@
 package main
 
-import "net/http"
+import (
+	"fmt"
+	"net/http"
+)
 
-func (app *application) logError(r http.Request, err error) {
-	app.logger.Info(err)
+// The logError() method is a generic helper for logging an error message.
+func (app *application) logError(r *http.Request, err error) {
+	app.logger.Info("dbasik error", "error", err)
+}
+
+// The errorResponse() method is a generic helper for sending JSON-formatted error
+// messages to the client with a given status code. Because we are using any we
+// we have flexibility over the values that we can include in the response.
+func (app *application) errorResponse(w http.ResponseWriter, r *http.Request, status int, message any) {
+	env := envelope{"error": message}
+
+	// Write the response using the writeJSON() helper. If it returns
+	// an error, log it and send the client an empty response with a
+	// 500 Internal Server status code.
+	if err := app.writeJSON(w, status, env, nil); err != nil {
+		app.logError(r, err)
+		w.WriteHeader(500)
+	}
+}
+
+// The serverErrorResponse() method will be used when our application encounters an
+// unexpected problem at runtime.
+func (app *application) serverErrorResponse(w http.ResponseWriter, r *http.Request, err error) {
+	app.logError(r, err)
+	message := "the server encountered a problem and could not process your request"
+	app.errorResponse(w, r, http.StatusInternalServerError, message)
+}
+
+// The notFoundResponse() method will be used to send a 404 status code and JSON response
+// to the client.
+func (app *application) notFoundResponse(w http.ResponseWriter, r *http.Request) {
+	message := "the requested resource could not be found"
+	app.errorResponse(w, r, http.StatusNotFound, message)
+}
+
+func (app *application) methodNotAllowed(w http.ResponseWriter, r *http.Request) {
+	message := fmt.Sprintf("the %s method is not supported for this resource", r.Method)
+	app.errorResponse(w, r, http.StatusMethodNotAllowed, message)
 }
diff --git a/cmd/api/healthcheck.go b/cmd/api/healthcheck.go
index 4c0a8fa..2e7914b 100644
--- a/cmd/api/healthcheck.go
+++ b/cmd/api/healthcheck.go
@@ -14,8 +14,6 @@ func (app *application) healthcheckHandler(w http.ResponseWriter, r *http.Reques
 	}
 	err := app.writeJSON(w, http.StatusOK, env, nil)
 	if err != nil {
-		app.logger.Debug("server error", "err", err)
-		http.Error(w, "The server encountered a problem and could not process your request", http.StatusInternalServerError)
-		return
+		app.serverErrorResponse(w, r, err)
 	}
 }