/
show_errors_middleware.go
188 lines (158 loc) · 4.46 KB
/
show_errors_middleware.go
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package web
import (
"bufio"
"html/template"
"net/http"
"os"
"runtime"
"strings"
)
// ShowErrorsMiddleware will catch panics and render an HTML page with the stack trace.
// This middleware should only be used in development.
func ShowErrorsMiddleware(rw ResponseWriter, req *Request, next NextMiddlewareFunc) {
defer func() {
if err := recover(); err != nil {
const size = 4096
stack := make([]byte, size)
stack = stack[:runtime.Stack(stack, false)]
renderPrettyError(rw, req, err, stack)
}
}()
next(rw, req)
}
func renderPrettyError(rw ResponseWriter, req *Request, err interface{}, stack []byte) {
_, filePath, line, _ := runtime.Caller(5)
data := map[string]interface{}{
"Error": err,
"Stack": string(stack),
"Params": req.URL.Query(),
"Method": req.Method,
"FilePath": filePath,
"Line": line,
"Lines": readErrorFileLines(filePath, line),
}
rw.Header().Set("Content-Type", "text/html")
rw.WriteHeader(http.StatusInternalServerError)
tpl := template.Must(template.New("ErrorPage").Parse(panicPageTpl))
tpl.Execute(rw, data)
}
func readErrorFileLines(filePath string, errorLine int) map[int]string {
lines := make(map[int]string)
file, err := os.Open(filePath)
if err != nil {
return lines
}
defer file.Close()
reader := bufio.NewReader(file)
currentLine := 0
for {
line, err := reader.ReadString('\n')
if err != nil || currentLine > errorLine+5 {
break
}
currentLine++
if currentLine >= errorLine-5 {
lines[currentLine] = strings.Replace(line, "\n", "", -1)
}
}
return lines
}
const panicPageTpl string = `
<html>
<head>
<title>Panic</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<style>
html, body{ padding: 0; margin: 0; }
header { background: #C52F24; color: white; border-bottom: 2px solid #9C0606; }
h1 { padding: 10px 0; margin: 0; }
.container { margin: 0 20px; }
.error { font-size: 18px; background: #FFCCCC; color: #9C0606; padding: 10px 0; }
.file-info .file-name { font-weight: bold; }
.stack { height: 300px; overflow-y: scroll; border: 1px solid #e5e5e5; padding: 10px; }
table.source {
width: 100%;
border-collapse: collapse;
border: 1px solid #e5e5e5;
}
table.source td {
padding: 0;
}
table.source .numbers {
font-size: 14px;
vertical-align: top;
width: 1%;
color: rgba(0,0,0,0.3);
text-align: right;
}
table.source .numbers .number {
display: block;
padding: 0 5px;
border-right: 1px solid #e5e5e5;
}
table.source .numbers .number.line-{{ .Line }} {
border-right: 1px solid #ffcccc;
}
table.source .numbers pre {
white-space: pre-wrap;
}
table.source .code {
font-size: 14px;
vertical-align: top;
}
table.source .code .line {
padding-left: 10px;
display: block;
}
table.source .numbers .number,
table.source .code .line {
padding-top: 1px;
padding-bottom: 1px;
}
table.source .code .line:hover {
background-color: #f6f6f6;
}
table.source .line-{{ .Line }},
table.source line-{{ .Line }},
table.source .code .line.line-{{ .Line }}:hover {
background: #ffcccc;
}
</style>
</head>
<body>
<header>
<div class="container">
<h1>Error</h1>
</div>
</header>
<div class="error">
<p class="container">{{ .Error }}</p>
</div>
<div class="container">
<p class="file-info">
In <span class="file-name">{{ .FilePath }}:{{ .Line }}</span></p>
</p>
<table class="source">
<tr>
<td class="numbers">
<pre>{{ range $lineNumber, $line := .Lines }}<span class="number line-{{ $lineNumber }}">{{ $lineNumber }}</span>{{ end }}</pre>
</td>
<td class="code">
<pre>{{ range $lineNumber, $line := .Lines }}<span class="line line-{{ $lineNumber }}">{{ $line }}<br /></span>{{ end }}</pre>
</td>
</tr>
</table>
<h2>Stack</h2>
<pre class="stack">{{ .Stack }}</pre>
<h2>Request</h2>
<p><strong>Method:</strong> {{ .Method }}</p>
<h3>Parameters:</h3>
<ul>
{{ range $key, $value := .Params }}
<li><strong>{{ $key }}:</strong> {{ $value }}</li>
{{ end }}
</ul>
</div>
</body>
</html>
`