1 files changed, 52 insertions, 0 deletions
diff --git a/cmd/web/helpers.go b/cmd/web/helpers.go
new file mode 100644
index 0000000..fc9b8f8
--- /dev/null
+++ b/cmd/web/helpers.go
@@ -0,0 +1,52 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+	"runtime/debug"
+)
+
+func (app *application) serverError(w http.ResponseWriter, r *http.Request, err error) {
+	var (
+		method = r.Method
+		uri    = r.URL.RequestURI()
+		trace  = string(debug.Stack())
+	)
+
+	app.logger.Error(err.Error(), "method", method, "uri", uri, "trace", trace)
+	log.Printf("Crash! %s %s %s", method, uri, trace)
+	http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
+}
+
+// The clientError helper sends a specific status code and corresponding description
+// to the user. We'll use this later in the book to send responses like 400 "Bad
+// Request" when there's a problem with the request that the user sent.
+func (app *application) clientError(w http.ResponseWriter, status int) {
+	http.Error(w, http.StatusText(status), status)
+}
+
+// notFound helper is a convenience wrapper around clientError which sends a 404 Not Found response
+func (app *application) notFound(w http.ResponseWriter) {
+	app.clientError(w, http.StatusNotFound)
+}
+
+func (app *application) render(w http.ResponseWriter, r *http.Request, status int, page string, data templateData) {
+	// retrieve the appropriate template set from the cache based on the page name.
+	// If no entry exists in the cache with the provided name, create a new error
+	// and call serverError() helper that we made earlier and return.
+	ts, ok := app.templateCache[page]
+	if !ok {
+		err := fmt.Errorf("the template %s does not exist", page)
+		app.serverError(w, r, err)
+		return
+	}
+
+	// Write out the provided HTTP status code('200 OK', '400 Bad Request', etc).
+	w.WriteHeader(status)
+
+	err := ts.ExecuteTemplate(w, "base", data)
+	if err != nil {
+		app.serverError(w, r, err)
+	}
+}