510 lines
16 KiB
Markdown
Vendored
510 lines
16 KiB
Markdown
Vendored
# Render [](http://godoc.org/github.com/unrolled/render) [](https://github.com/unrolled/render/actions)
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Render is a package that provides functionality for easily rendering JSON, XML, text, binary data, and HTML templates. This package is based on the [Martini](https://github.com/go-martini/martini) [render](https://github.com/martini-contrib/render) work.
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## Block Deprecation Notice
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Go 1.6 introduces a new [block](https://github.com/golang/go/blob/release-branch.go1.6/src/html/template/example_test.go#L128) action. This conflicts with Render's included `block` template function. To provide an easy migration path, a new function was created called `partial`. It is a duplicate of the old `block` function. It is advised that all users of the `block` function update their code to avoid any issues in the future. Previous to Go 1.6, Render's `block` functionality will continue to work but a message will be logged urging you to migrate to the new `partial` function.
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## Usage
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Render can be used with pretty much any web framework providing you can access the `http.ResponseWriter` from your handler. The rendering functions simply wraps Go's existing functionality for marshaling and rendering data.
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- HTML: Uses the [html/template](http://golang.org/pkg/html/template/) package to render HTML templates.
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- JSON: Uses the [encoding/json](http://golang.org/pkg/encoding/json/) package to marshal data into a JSON-encoded response.
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- XML: Uses the [encoding/xml](http://golang.org/pkg/encoding/xml/) package to marshal data into an XML-encoded response.
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- Binary data: Passes the incoming data straight through to the `http.ResponseWriter`.
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- Text: Passes the incoming string straight through to the `http.ResponseWriter`.
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~~~ go
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// main.go
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package main
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import (
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"encoding/xml"
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"net/http"
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"github.com/unrolled/render" // or "gopkg.in/unrolled/render.v1"
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)
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type ExampleXml struct {
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XMLName xml.Name `xml:"example"`
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One string `xml:"one,attr"`
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Two string `xml:"two,attr"`
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}
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func main() {
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r := render.New()
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mux := http.NewServeMux()
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mux.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
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w.Write([]byte("Welcome, visit sub pages now."))
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})
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mux.HandleFunc("/data", func(w http.ResponseWriter, req *http.Request) {
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r.Data(w, http.StatusOK, []byte("Some binary data here."))
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})
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mux.HandleFunc("/text", func(w http.ResponseWriter, req *http.Request) {
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r.Text(w, http.StatusOK, "Plain text here")
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})
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mux.HandleFunc("/json", func(w http.ResponseWriter, req *http.Request) {
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r.JSON(w, http.StatusOK, map[string]string{"hello": "json"})
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})
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mux.HandleFunc("/jsonp", func(w http.ResponseWriter, req *http.Request) {
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r.JSONP(w, http.StatusOK, "callbackName", map[string]string{"hello": "jsonp"})
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})
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mux.HandleFunc("/xml", func(w http.ResponseWriter, req *http.Request) {
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r.XML(w, http.StatusOK, ExampleXml{One: "hello", Two: "xml"})
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})
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mux.HandleFunc("/html", func(w http.ResponseWriter, req *http.Request) {
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// Assumes you have a template in ./templates called "example.tmpl"
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// $ mkdir -p templates && echo "<h1>Hello {{.}}.</h1>" > templates/example.tmpl
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r.HTML(w, http.StatusOK, "example", "World")
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})
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http.ListenAndServe("127.0.0.1:3000", mux)
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}
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~~~
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~~~ html
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<!-- templates/example.tmpl -->
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<h1>Hello {{.}}.</h1>
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~~~
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### Available Options
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Render comes with a variety of configuration options _(Note: these are not the default option values. See the defaults below.)_:
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~~~ go
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// ...
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r := render.New(render.Options{
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Directory: "templates", // Specify what path to load the templates from.
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FileSystem: &LocalFileSystem{}, // Specify filesystem from where files are loaded.
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Asset: func(name string) ([]byte, error) { // Load from an Asset function instead of file.
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return []byte("template content"), nil
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},
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AssetNames: func() []string { // Return a list of asset names for the Asset function
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return []string{"filename.tmpl"}
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},
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Layout: "layout", // Specify a layout template. Layouts can call {{ yield }} to render the current template or {{ partial "css" }} to render a partial from the current template.
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Extensions: []string{".tmpl", ".html"}, // Specify extensions to load for templates.
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Funcs: []template.FuncMap{AppHelpers}, // Specify helper function maps for templates to access.
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Delims: render.Delims{"{[{", "}]}"}, // Sets delimiters to the specified strings.
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Charset: "UTF-8", // Sets encoding for content-types. Default is "UTF-8".
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DisableCharset: true, // Prevents the charset from being appended to the content type header.
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IndentJSON: true, // Output human readable JSON.
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IndentXML: true, // Output human readable XML.
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PrefixJSON: []byte(")]}',\n"), // Prefixes JSON responses with the given bytes.
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PrefixXML: []byte("<?xml version='1.0' encoding='UTF-8'?>"), // Prefixes XML responses with the given bytes.
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HTMLContentType: "application/xhtml+xml", // Output XHTML content type instead of default "text/html".
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IsDevelopment: true, // Render will now recompile the templates on every HTML response.
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UnEscapeHTML: true, // Replace ensure '&<>' are output correctly (JSON only).
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StreamingJSON: true, // Streams the JSON response via json.Encoder.
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RequirePartials: true, // Return an error if a template is missing a partial used in a layout.
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DisableHTTPErrorRendering: true, // Disables automatic rendering of http.StatusInternalServerError when an error occurs.
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})
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// ...
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~~~
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### Default Options
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These are the preset options for Render:
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~~~ go
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r := render.New()
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// Is the same as the default configuration options:
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r := render.New(render.Options{
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Directory: "templates",
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FileSystem: &LocalFileSystem{},
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Asset: nil,
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AssetNames: nil,
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Layout: "",
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Extensions: []string{".tmpl"},
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Funcs: []template.FuncMap{},
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Delims: render.Delims{"{{", "}}"},
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Charset: "UTF-8",
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DisableCharset: false,
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IndentJSON: false,
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IndentXML: false,
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PrefixJSON: []byte(""),
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PrefixXML: []byte(""),
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BinaryContentType: "application/octet-stream",
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HTMLContentType: "text/html",
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JSONContentType: "application/json",
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JSONPContentType: "application/javascript",
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TextContentType: "text/plain",
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XMLContentType: "application/xhtml+xml",
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IsDevelopment: false,
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UnEscapeHTML: false,
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StreamingJSON: false,
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RequirePartials: false,
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DisableHTTPErrorRendering: false,
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})
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~~~
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### JSON vs Streaming JSON
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By default, Render does **not** stream JSON to the `http.ResponseWriter`. It instead marshalls your object into a byte array, and if no errors occurred, writes that byte array to the `http.ResponseWriter`. If you would like to use the built it in streaming functionality (`json.Encoder`), you can set the `StreamingJSON` setting to `true`. This will stream the output directly to the `http.ResponseWriter`. Also note that streaming is only implemented in `render.JSON` and not `render.JSONP`, and the `UnEscapeHTML` and `Indent` options are ignored when streaming.
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### Loading Templates
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By default Render will attempt to load templates with a '.tmpl' extension from the "templates" directory. Templates are found by traversing the templates directory and are named by path and basename. For instance, the following directory structure:
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~~~
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templates/
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|__ admin/
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|__ home.tmpl
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~~~
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Will provide the following templates:
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~~~
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admin/index
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admin/edit
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home
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~~~
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You can also load templates from memory by providing the Asset and AssetNames options,
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e.g. when generating an asset file using [go-bindata](https://github.com/jteeuwen/go-bindata).
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### Layouts
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Render provides `yield` and `partial` functions for layouts to access:
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~~~ go
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// ...
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r := render.New(render.Options{
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Layout: "layout",
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})
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// ...
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~~~
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~~~ html
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<!-- templates/layout.tmpl -->
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<html>
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<head>
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<title>My Layout</title>
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<!-- Render the partial template called `css-$current_template` here -->
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{{ partial "css" }}
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</head>
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<body>
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<!-- render the partial template called `header-$current_template` here -->
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{{ partial "header" }}
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<!-- Render the current template here -->
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{{ yield }}
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<!-- render the partial template called `footer-$current_template` here -->
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{{ partial "footer" }}
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</body>
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</html>
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~~~
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`current` can also be called to get the current template being rendered.
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~~~ html
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<!-- templates/layout.tmpl -->
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<html>
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<head>
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<title>My Layout</title>
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</head>
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<body>
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This is the {{ current }} page.
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</body>
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</html>
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~~~
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Partials are defined by individual templates as seen below. The partial template's
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name needs to be defined as "{partial name}-{template name}".
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~~~ html
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<!-- templates/home.tmpl -->
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{{ define "header-home" }}
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<h1>Home</h1>
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{{ end }}
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{{ define "footer-home"}}
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<p>The End</p>
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{{ end }}
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~~~
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By default, the template is not required to define all partials referenced in the
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layout. If you want an error to be returned when a template does not define a
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partial, set `Options.RequirePartials = true`.
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### Character Encodings
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Render will automatically set the proper Content-Type header based on which function you call. See below for an example of what the default settings would output (note that UTF-8 is the default, and binary data does not output the charset):
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~~~ go
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// main.go
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package main
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import (
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"encoding/xml"
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"net/http"
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"github.com/unrolled/render" // or "gopkg.in/unrolled/render.v1"
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)
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type ExampleXml struct {
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XMLName xml.Name `xml:"example"`
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One string `xml:"one,attr"`
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Two string `xml:"two,attr"`
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}
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func main() {
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r := render.New(render.Options{})
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mux := http.NewServeMux()
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// This will set the Content-Type header to "application/octet-stream".
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// Note that this does not receive a charset value.
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mux.HandleFunc("/data", func(w http.ResponseWriter, req *http.Request) {
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r.Data(w, http.StatusOK, []byte("Some binary data here."))
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})
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// This will set the Content-Type header to "application/json; charset=UTF-8".
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mux.HandleFunc("/json", func(w http.ResponseWriter, req *http.Request) {
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r.JSON(w, http.StatusOK, map[string]string{"hello": "json"})
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})
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// This will set the Content-Type header to "text/xml; charset=UTF-8".
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mux.HandleFunc("/xml", func(w http.ResponseWriter, req *http.Request) {
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r.XML(w, http.StatusOK, ExampleXml{One: "hello", Two: "xml"})
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})
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// This will set the Content-Type header to "text/plain; charset=UTF-8".
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mux.HandleFunc("/text", func(w http.ResponseWriter, req *http.Request) {
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r.Text(w, http.StatusOK, "Plain text here")
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})
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// This will set the Content-Type header to "text/html; charset=UTF-8".
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mux.HandleFunc("/html", func(w http.ResponseWriter, req *http.Request) {
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// Assumes you have a template in ./templates called "example.tmpl"
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// $ mkdir -p templates && echo "<h1>Hello {{.}}.</h1>" > templates/example.tmpl
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r.HTML(w, http.StatusOK, "example", "World")
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})
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http.ListenAndServe("127.0.0.1:3000", mux)
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}
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~~~
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In order to change the charset, you can set the `Charset` within the `render.Options` to your encoding value:
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~~~ go
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// main.go
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package main
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import (
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"encoding/xml"
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"net/http"
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"github.com/unrolled/render" // or "gopkg.in/unrolled/render.v1"
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)
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type ExampleXml struct {
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XMLName xml.Name `xml:"example"`
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One string `xml:"one,attr"`
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Two string `xml:"two,attr"`
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}
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func main() {
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r := render.New(render.Options{
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Charset: "ISO-8859-1",
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})
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mux := http.NewServeMux()
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// This will set the Content-Type header to "application/octet-stream".
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// Note that this does not receive a charset value.
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mux.HandleFunc("/data", func(w http.ResponseWriter, req *http.Request) {
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r.Data(w, http.StatusOK, []byte("Some binary data here."))
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})
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// This will set the Content-Type header to "application/json; charset=ISO-8859-1".
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mux.HandleFunc("/json", func(w http.ResponseWriter, req *http.Request) {
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r.JSON(w, http.StatusOK, map[string]string{"hello": "json"})
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})
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// This will set the Content-Type header to "text/xml; charset=ISO-8859-1".
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mux.HandleFunc("/xml", func(w http.ResponseWriter, req *http.Request) {
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r.XML(w, http.StatusOK, ExampleXml{One: "hello", Two: "xml"})
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})
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// This will set the Content-Type header to "text/plain; charset=ISO-8859-1".
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mux.HandleFunc("/text", func(w http.ResponseWriter, req *http.Request) {
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r.Text(w, http.StatusOK, "Plain text here")
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})
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// This will set the Content-Type header to "text/html; charset=ISO-8859-1".
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mux.HandleFunc("/html", func(w http.ResponseWriter, req *http.Request) {
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// Assumes you have a template in ./templates called "example.tmpl"
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// $ mkdir -p templates && echo "<h1>Hello {{.}}.</h1>" > templates/example.tmpl
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r.HTML(w, http.StatusOK, "example", "World")
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})
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http.ListenAndServe("127.0.0.1:3000", mux)
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}
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~~~
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### Error Handling
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The rendering functions return any errors from the rendering engine.
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By default, they will also write the error to the HTTP response and set the status code to 500. You can disable
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this behavior so that you can handle errors yourself by setting
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`Options.DisableHTTPErrorRendering: true`.
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~~~go
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r := render.New(render.Options{
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DisableHTTPErrorRendering: true,
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})
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//...
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err := r.HTML(w, http.StatusOK, "example", "World")
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if err != nil{
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http.Redirect(w, r, "/my-custom-500", http.StatusFound)
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}
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~~~
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## Integration Examples
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### [Echo](https://github.com/labstack/echo)
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~~~ go
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// main.go
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package main
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import (
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"io"
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"net/http"
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"github.com/labstack/echo"
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"github.com/unrolled/render" // or "gopkg.in/unrolled/render.v1"
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)
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type RenderWrapper struct { // We need to wrap the renderer because we need a different signature for echo.
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rnd *render.Render
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}
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func (r *RenderWrapper) Render(w io.Writer, name string, data interface{},c echo.Context) error {
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return r.rnd.HTML(w, 0, name, data) // The zero status code is overwritten by echo.
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}
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func main() {
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r := &RenderWrapper{render.New()}
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e := echo.New()
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e.Renderer = r
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e.GET("/", func(c echo.Context) error {
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return c.Render(http.StatusOK, "TemplateName", "TemplateData")
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})
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e.Logger.Fatal(e.Start(":1323"))
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}
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~~~
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### [Gin](https://github.com/gin-gonic/gin)
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~~~ go
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// main.go
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package main
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import (
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"net/http"
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"github.com/gin-gonic/gin"
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"github.com/unrolled/render" // or "gopkg.in/unrolled/render.v1"
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)
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func main() {
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r := render.New(render.Options{
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IndentJSON: true,
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})
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router := gin.Default()
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router.GET("/", func(c *gin.Context) {
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r.JSON(c.Writer, http.StatusOK, map[string]string{"welcome": "This is rendered JSON!"})
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})
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router.Run(":3000")
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}
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~~~
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### [Goji](https://github.com/zenazn/goji)
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~~~ go
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// main.go
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package main
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import (
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"net/http"
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"github.com/zenazn/goji"
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"github.com/zenazn/goji/web"
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"github.com/unrolled/render" // or "gopkg.in/unrolled/render.v1"
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)
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func main() {
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r := render.New(render.Options{
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IndentJSON: true,
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})
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goji.Get("/", func(c web.C, w http.ResponseWriter, req *http.Request) {
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r.JSON(w, http.StatusOK, map[string]string{"welcome": "This is rendered JSON!"})
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})
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goji.Serve() // Defaults to ":8000".
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}
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~~~
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### [Negroni](https://github.com/codegangsta/negroni)
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~~~ go
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// main.go
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package main
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import (
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"net/http"
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"github.com/urfave/negroni"
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"github.com/unrolled/render" // or "gopkg.in/unrolled/render.v1"
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)
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func main() {
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r := render.New(render.Options{
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IndentJSON: true,
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})
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mux := http.NewServeMux()
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mux.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
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r.JSON(w, http.StatusOK, map[string]string{"welcome": "This is rendered JSON!"})
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})
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n := negroni.Classic()
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n.UseHandler(mux)
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n.Run(":3000")
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}
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~~~
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### [Traffic](https://github.com/pilu/traffic)
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~~~ go
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// main.go
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package main
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import (
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"net/http"
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"github.com/pilu/traffic"
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"github.com/unrolled/render" // or "gopkg.in/unrolled/render.v1"
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)
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func main() {
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r := render.New(render.Options{
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|
IndentJSON: true,
|
|
})
|
|
|
|
router := traffic.New()
|
|
router.Get("/", func(w traffic.ResponseWriter, req *traffic.Request) {
|
|
r.JSON(w, http.StatusOK, map[string]string{"welcome": "This is rendered JSON!"})
|
|
})
|
|
|
|
router.Run()
|
|
}
|
|
~~~
|