[core] Embedded and implement http.Pusher into http.ResponseWriter+gzip Writer (#47)

* added http Pusher interface to gzip response writer

* implement Pusher on gzipResponseWriter and pass encoding header to pusher options

* providing a generic error view fuction for code that calls a interface method which will have access to the response

* fix []byte -> string type for fmt string

* adding the res, req pattern for method arguments in interfaces and their method calls

* fix for spacing in generic error message

* remove default error views displayed in lifecycle hooks - will rely on custom views or redirects inside hook now that user has ResponseWriter. Otherwise, multiple WriteHeader calls would be warned

* removing WriteHeader calls before return in external handlers

* bump version 0.8.1

1 files changed, 20 insertions, 0 deletions

diff --git a/system/admin/admin.go b/system/admin/admin.go
index 3df6805..7761e71 100644
--- a/system/admin/admin.go
+++ b/system/admin/admin.go
@@ -5,6 +5,7 @@ package admin
 import (
 	"bytes"
 	"encoding/json"
+	"fmt"
 	"html/template"
 	"net/http"
 
@@ -607,3 +608,22 @@ var err500HTML = []byte(`
 func Error500() ([]byte, error) {
 	return Admin(err500HTML)
 }
+
+var errMessageHTML = `
+<div class="error-page eMsg col s6">
+<div class="card">
+<div class="card-content">
+    <div class="card-title"><b>Error:&nbsp;</b>%s</div>
+    <blockquote>%s</blockquote>
+</div>
+</div>
+</div>
+`
+
+// ErrorMessage is a generic error message container, similar to Error500() and
+// others in this package, ecxept it expects the caller to provide a title and
+// message to describe to a view why the error is being shown
+func ErrorMessage(title, message string) ([]byte, error) {
+	eHTML := fmt.Sprintf(errMessageHTML, title, message)
+	return Admin([]byte(eHTML))
+}