Templator is alternative view on html templates for go - on my opinion, standard package "text/templates" offer awful syntax!
Why syntax in the templates must be different from the GO syntax?
- Coplex html templates become pretty hard to understand.
- Functions\pipeline calls are also very poor, we have to write functions such as eq, more, less, et.c.
Templator generate go code from simply templates(*.gtm).
HTML template - it function, with full syntax GO. Template functions returned []byte HTML code.
- manually execute
gotemplator /path/to/dir
OR use go generate:
- add to your project:
//go:generate gotemplator /path/to/dir/and executego generate
Template syntax is hybrid of html and go, have only 4 rules:
-
if the line begins with
||- then this is go code which is unchanged moved to go file -
if the line like
||=Header(somevariable)- then should call another section or any function returned[]byte, it's converted tow.Write(Header(somevariable)) -
code in
{{=var}}- is short print variable, converted tofmt.Fprintf(w, "%v", var) -
simple ternary operator -
{{?condition?then:else}}, ex:class='{{?len(val)>10?"long":"short"}}'
everything else is html - which moved to go file how w.Write([]byte(string))
example:
|| template Index(users []string)
<!DOCTYPE html>
<html>
<head>
<title></title>
</head>
<body>
<ul>
|| for i, val := range users {
<li>{{?i==0?"selected":i}} {{=val}}</li>
// {{=key}} - this is comment and will not be in the .go file
|| }
</ul>
</body>
</html>
|| endthis is transform to:
package templates
import (
"bytes"
"fmt"
)
func Index(users []string) []byte {
w := new(bytes.Buffer)
w.Write([]byte("\t<!DOCTYPE html>\n\t<html>\n\t\t<head>\n\t\t\t<title></title>\n\t\t</head>\n\t\t<body>\n\t\t\t<ul>"))
for i, val := range users {
w.Write([]byte("\t\t\t\t<li>"))
if i == 0 {
fmt.Fprintf(w, "%v", "selected")
} else {
fmt.Fprintf(w, "%v", i)
}
fmt.Fprintf(w, " %v</li>", val)
}
w.Write([]byte("\t\t\t</ul>\n\t\t</body>\n\t</html>"))
return w.Bytes()
}If in template arguments exist w io.Writer, then html code will be written to it:
|| template IndexWriter(w io.Writer, users []string)
<!DOCTYPE html>
<html>
<head>
<title></title>
</head>
<body>
<ul>
|| for i, val := range users {
<li>{{?i==0?"selected":i}} {{=val}}</li>
// {{=key}} - this is comment and will not be in the .go file
|| }
</ul>
</body>
</html>
|| end
func IndexWriter(w io.Writer, users []string) {
w.Write([]byte("\t<!DOCTYPE html>\n\t<html>\n\t\t<head>\n\t\t\t<title></title>\n\t\t</head>\n\t\t<body>\n\t\t\t<ul>"))
for i, val := range users {
w.Write([]byte("\t\t\t\t<li>"))
if i == 0 {
fmt.Fprintf(w, "%v", "selected")
} else {
fmt.Fprintf(w, "%v", i)
}
fmt.Fprintf(w, " %v</li>", val)
}
w.Write([]byte("\t\t\t</ul>\n\t\t</body>\n\t</html>"))
}Templator support ternary operator:
{{?if>10?"something"}} converted to:
if > 10 {
fmt.Fprintf(w, "%v", "something")
}and with else condition - {{?i>10?"something":"if condition false"}}:
if i > 10 {
fmt.Fprintf(w, "%v", "something")
} else {
fmt.Fprintf(w, "%v", "if condition false")
}GoTemplator slower than Hero as uses fmt.Fprintf() for write user varables and internal creation of bytes.Buffer.
BenchmarkTemplator-8 500000 4157 ns/op 928 B/op 7 allocs/op
BenchmarkTemplatorWriter-8 1000000 1000 ns/op 531 B/op 3 allocs/op
BenchmarkHero-8 2000000 553 ns/op 453 B/op 0 allocs/op