I need to create an html page that display all the "forums" present in the database in my .html file.
Example:
<body>
{{with index . 0}}
{{.Name}}<br>{{.Descr}}</td>
{{end}}
{{with index . 1}}
{{.Name}}<br>{{.Descr}}
{{end}}
</body>
func index(w http.ResponseWriter, r *http.Request) {
forums := GetForumsFromDB() // return a slice of type Forum from the db
tpl.ExecuteTemplate(w, "index.html", forums)
}
type Forum struct {
Id int
Name string
Descr string
}
But in this case I need to already know how many forums are there in the db when writing the .html file. How should I approach this? Should I pass the html into the template together with my slice? Should I use a method of Forum that return the html for every forum?
Use range:
{{range .}}
{{.Name}}<br>{{.Descr}}
{{end}}
Have gin-gonic web app.
There are 3 files:
1) base.html -- base layout file
<!DOCTYPE html>
<html lang="en">
<body>
header...
{{template "content" .}}
footer...
</body>
</html>
2) page1.html, for /page1
{{define "content"}}
<div>
<h1>Page1</h1>
</div>
{{end}}
{{template "base.html"}}
3) page2.html, for /page2
{{define "content"}}
<div>
<h1>Page2</h1>
</div>
{{end}}
{{template "base.html"}}
The problem is that /page1 and /page2 use one template - page2.html. I think that I have misunderstanding of such constructions: {{define "content"}}, {{template "base.html"}}.
Please, can you show an example how to use base layouts in golang?
You can use the base.html as long as you parse the template along with your "content", like so:
base.html
{{define "base"}}
<!DOCTYPE html>
<html lang="en">
<body>
header...
{{template "content" .}}
footer...
</body>
</html>
{{end}}
page1.html
{{define "content"}}
I'm page 1
{{end}}
page2.html
{{define "content"}}
I'm page 2
{{end}}
then ParseFiles with ("your-page.html", "base.html"), and ExecuteTemplate with your context.
tmpl, err := template.New("").ParseFiles("page1.html", "base.html")
// check your err
err = tmpl.ExecuteTemplate(w, "base", yourContext)
Go 1.16 introduces the embed package, which packages non-.go files into binaries, greatly facilitating the deployment of Go programs. The ParseFS function was also added to the standard library html/template, which compiles all the template files contained in embed.FS into a template tree.
// templates.go
package templates
import (
"embed"
"html/template"
)
//go:embed views/*.html
var tmplFS embed.FS
type Template struct {
templates *template.Template
}
func New() *Template {
funcMap := template.FuncMap{
"inc": inc,
}
templates := template.Must(template.New("").Funcs(funcMap).ParseFS(tmplFS, "views/*.html"))
return &Template{
templates: templates,
}
}
// main.go
t := templates.New()
t.templates is a global template that contains all matching views/*.html templates, all of which are related and can be referenced to each other, and the name of the template is the name of the file, e.g. article.html.
Further, we define a Render method for the *Template type, which implements the Renderer interface of the Echo web framework.
// templates.go
func (t *Template) Render(w io.Writer, name string, data interface{}, c echo.Context) error {
return t.templates.ExecuteTemplate(w, name, data)
}
You can then specify the renderer for Echo to facilitate generating HTML responses at each handler, simply by passing the name of the template to the c.Render function.
// main.go
func main() {
t := templates.New()
e := echo.New()
e.Renderer = t
}
// handler.go
func (h *Handler) articlePage(c echo.Context) error {
id := c.Param("id")
article, err := h.service.GetArticle(c.Request().Context(), id)
...
return c.Render(http.StatusOK, "article.html", article)
}
Since the t.templates template contains all the parsed templates, each template name can be used directly.
In order to assemble HTMLs, we need to use template inheritance. For example, define a layout.html for the basic HTML frame and the <head> element, and set {{block "title"}} and {{block "content"}}, other templates inherit layout.html, and populate or override the layout template's blocks of the same name with their own defined blocks.
The following is the content of the layout.html template.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>{{block "title" .}}{{end}}</title>
<script src="/static/main.js"></script>
</head>
<body>
<div class="main">{{block "content" .}}{{end}}</div>
</body>
</html>
For other templates, you can refer to (inherit from) layout.html and define the blocks in the layout.html template.
For example, login.html reads as follows.
{{template "layout.html" .}}
{{define "title"}}Login{{end}}
{{define "content"}}
<form class="account-form" method="post" action="/account/login" data-controller="login">
<div div="account-form-title">Login</div>
<input type="phone" name="phone" maxlength="13" class="account-form-input" placeholder="Phone" tabindex="1">
<div class="account-form-field-submit ">
<button type="submit" class="btn btn-phone">Login</button>
</div>
</form>
{{end}}
article.html also references layout.html:
{{template "layout.html" .}}
{{define "title"}}<h1>{{.Title}}</h1>{{end}}
{{define "content"}}
<p>{{.URL}}</p>
<article>{{.Content}}</article>
{{end}}
We would expect the blocks defined in the login.html template to override the blocks in layout.html when rendering it, and also when rendering the article.html template. But that's not the case, and it's down to the Go text/template implementation. In our implementation of ParseFS(tmplFS, "views/*.html"), suppose article.html is parsed first and its content block is parsed as a template name, then when the login.html template is parsed later and acontent block is also found in it, text/template will overwrite the template of the same name with the later parsed content, so when all the templates are parsed, there is actually only one template named content in our template tree, which is the content defined in the last parsed template file.
Therefore, when we execute the article.html template, it is possible that the content template is not the content defined in this template, but the content defined in other templates.
The community has proposed some solutions to this problem. For example, instead of using a global template, a new template is created each time it is rendered, containing only the contents of layout.html and the sub-template. But this is really tedious. In fact, when Go 1.6 introduced the block directive [1] for text/template, we were able to do what we wanted with the Clone method, with just a few changes to the code above.
// templates.go
package templates
import (
"embed"
"html/template"
"io"
"github.com/labstack/echo/v4"
)
//go:embed views/*.html
var tmplFS embed.FS
type Template struct {
templates *template.Template
}
func New() *Template {
funcMap := template.FuncMap{
"inc": inc,
}
templates := template.Must(template.New("").Funcs(funcMap).ParseFS(tmplFS, "views/*.html"))
return &Template{
templates: templates,
}
}
func (t *Template) Render(w io.Writer, name string, data interface{}, c echo.Context) error {
tmpl := template.Must(t.templates.Clone())
tmpl = template.Must(tmpl.ParseFS(tmplFS, "views/"+name))
return tmpl.ExecuteTemplate(w, name, data)
}
You can see that only the Render function has been modified here. Instead of executing the global template, we will clone it into a new template, and the content block in this new template may not be the one we want, so here we parse the content of a sub-template we will eventually render on top of this global template, so that the content of the newly added sub-template will overwrite the previous, possibly incorrect content. Our target sub-template references layout.html in the global template, which is not conflicted, and since the global template is never executed (we clone a new global template in the Render function each time it is executed), it is also clean. When a template is finally executed, we have a clean layout.html with the content content we want, which is equivalent to generating a new template each time we execute it, which contains only the layout template and sub-templates we need. The idea is the same, but instead of manually generating a new template when executing the template, it's done automatically in the Render function.
Of course, you can also use {{ template }} to refer to other layout templates in the sub-template, as long as these layout templates do not overwrite each other, you just need to specify the name of the target sub-template when executing, and the template engine will automatically use the {{ template }} tag defined in it to find the layout templates for us, which are all in the cloned global template.
[1] https://github.com/golang/go/commit/12dfc3bee482f16263ce4673a0cce399127e2a0d
As far as I understand, when you use ParseGlob(), Gin parses all the matching files and creates a single template object from them. For doing what you want, you'd need two different templates (one for page 1, another for page 2).
Gin documentation says this is a known limitation and points the way to overcome it:
Gin allow by default use only one html.Template. Check a multitemplate render for using features like go 1.6 block template.
Using the multitemplate library, you can write something like this:
render := multitemplate.NewRenderer()
render.AddFromFiles("page1", "templates/base.html", "templates/page1.html")
render.AddFromFiles("page2", "templates/base.html", "templates/page2.html")
router := gin.Default()
router.HTMLRender = render
// Later
ginContext.HTML(200, "page1", gin.H{
"title": "The Wonderful Page One",
})
This requires more manual setup than I'd hope for, but gets the job done.
The easiest way which avoids a map and works in a single template:
base.html
<!DOCTYPE html>
<html lang="en">
<body>
header...
{{block "content" .}}{{end}}
footer...
</body>
</html>
page1.html
{{template "base.html" .}}
{{define "content"}}This is page 1{{end}}
page2.html
{{template "base.html" .}}
{{define "content"}}This is page 2{{end}}
t := template.Must(template.ParseGlob("*.html"))
err := t.ExecuteTemplate(w, "page1.html", context)
err := t.ExecuteTemplate(w, "page2.html", context)
Is it possible to use template layouts in Revel. For example have a root.html which contains a {{define "main"}}{{end}} tag. Then call ExecuteTemplate(out, "main", nil) http://golang.org/pkg/html/template/#Template.ExecuteTemplate
Something like c.RenderLayout()
You can define the do you want into conf/routes file.
Then you can call you action with the name you want:
package controllers
import (
"github.com/revel/revel"
)
func (c Name) root() revel.Result {
c.Render()
}
views/Name/root.html
Other way can be this:
views/Controler/NameAction.html
{{template "root.html" .}}
views/root.html
<p>bla, bla</p>
I'm trying to generate a web page in Go lang. I'm currently using the Goji framework ( http://goji.io ) and I want to generate all of the heads and parts of the body of the web-page, but then I want some of the content to be written based on results from the code.
For example as in PHP, one can write HTML, js, or CSS and then in the PHP tags, write the code which is interpreted there.
How can I write my html, css, and js and then have Golang code within it that is complied and executed as the page is rendered?
As mentioned in issue 13, use Go html/template package.
i.e.
// Shorthand
type M map[string]interface{}
func viewHandler(c web.C, w http.ResponseWriter, r *http.Request) {
title := c.URLParams["title"]
p, err := loadPage(title)
if err != nil {
...
}
// do other things
template.ExecuteTemplate(w, "results.html", M{
"title": title,
"results": results,
"pagination": true,
}
}
results.html
{{range .Results }}
<h1>{{ Result.Name }}</h1>
<p>{{ Result.Body }}</p>
{{ end }}
Using a template is also recommended in zenazn/goji/example/main.go.
elithrar also references in the comments the "Writing Web Applications article, section The html/template package" for more.
Before I being a bit of background, I am very new to go programming language. I am running go on Win 7, latest go package installer for windows. I'm not good at coding but I do like some challenge of learning a new language. I wanted to start learn Erlang but found go very interesting based on the GO I/O videos in youtube.
I'm having problem with capturing POST form values in GO. I spend three hours yesterday to get go to print a POST form value in the browser and failed miserably. I don't know what I'm doing wrong, can anyone point me to the right direction? I can easily do this in another language like C#, PHP, VB, ASP, Rails etc. I have search the entire interweb and haven't found a working sample. Below is my sample code.
Here is Index.html page
{{ define "title" }}Homepage{{ end }}
{{ define "content" }}
<h1>My Homepage</h1>
<p>Hello, and welcome to my homepage!</p>
<form method="POST" action="/">
<p> Enter your name : <input type="text" name="username"> </P>
<p> <button>Go</button>
</form>
<br /><br />
{{ end }}
Here is the base page
<!DOCTYPE html>
<html lang="en">
<head>
<title>{{ template "title" . }}</title>
</head>
<body>
<section id="contents">
{{ template "content" . }}
</section>
<footer id="footer">
My homepage 2012 copy
</footer>
</body>
</html>
now some go code
package main
import (
"fmt"
"http"
"strings"
"html/template"
)
var index = template.Must(template.ParseFiles(
"templates/_base.html",
"templates/index.html",
))
func GeneralHandler(w http.ResponseWriter, r *http.Request) {
index.Execute(w, nil)
if r.Method == "POST" {
a := r.FormValue("username")
fmt.Fprintf(w, "hi %s!",a); //<-- this variable does not rendered in the browser!!!
}
}
func helloHandler(w http.ResponseWriter, r *http.Request) {
remPartOfURL := r.URL.Path[len("/hello/"):]
fmt.Fprintf(w, "Hello %s!", remPartOfURL)
}
func main() {
http.HandleFunc("/", GeneralHandler)
http.HandleFunc("/hello/", helloHandler)
http.ListenAndServe("localhost:81", nil)
}
Thanks!
PS: Very tedious to add four space before every line of code in stackoverflow especially when you are copy pasting. Didn't find it very user friendly or is there an easier way?
Writing to the ResponseWriter (by calling Execute) before reading the value from the request is clearing it out.
You can see this in action if you use this request handler:
func GeneralHandler(w http.ResponseWriter, r *http.Request) {
fmt.Println(r.Method)
fmt.Println(r.URL)
fmt.Println("before",r.FormValue("username"))
index.Execute(w, nil)
if r.Method == "POST" {
fmt.Println("after",r.FormValue("username"))
}
}
This will print out before and after. However, in this case:
func GeneralHandler(w http.ResponseWriter, r *http.Request) {
fmt.Println(r.Method)
fmt.Println(r.URL)
index.Execute(w, nil)
if r.Method == "POST" {
fmt.Println("after",r.FormValue("username"))
}
}
The after value will be blank.
According to the documentation for html/template the second argument to Execute should be the data you want to put in the template.
Add a {{.}} somewhere in your template and then pass the string you want printed in as the second argument. It should get rendered as part of the template.