README
¶
templatereloader
A templatereloader is a jaws.TemplateLookuper that will reload templates from
disk as needed if running with -tags debug or -race. If not, it simply calls
template.New("").ParseFS(fsys, fpath) and returns the parsed *template.Template
directly, adding no per-lookup indirection.
For example usage, see jawsboot/README.md
Documentation
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Overview ¶
Package templatereloader provides a jaws.TemplateLookuper that reparses templates from disk while running in debug or race builds.
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func New ¶
New returns a jaws.TemplateLookuper for the templates matched by fpath.
In normal builds the templates are parsed once from fsys. When deadlock.Debug is set (race or debug builds) it instead returns a TemplateReloader that reparses from disk under relpath, so template edits take effect without a restart; fsys is then unused.
The debug-build concrete type is observable via a type assertion to *TemplateReloader, whose TemplateReloader.LastError and TemplateReloader.Path expose reload diagnostics; in normal builds the value is a plain *html/template.Template and there are no reload diagnostics to report.
Because the two builds resolve templates differently, fpath must be a valid pattern under both io/fs.Glob (used against fsys in normal builds) and path/filepath.Glob (used against the on-disk tree in debug builds), and relpath must point at the on-disk root that mirrors the embedded fsys layout so that path.Join(relpath, fpath) matches the same templates on disk.
Types ¶
type TemplateReloader ¶
type TemplateReloader struct {
// contains filtered or unexported fields
}
TemplateReloader reloads and reparses templates if more than one second has passed since the last reload.
func (*TemplateReloader) LastError ¶ added in v0.500.0
func (tr *TemplateReloader) LastError() (err error)
LastError returns the last reload parse error, or nil after a successful reload.
It is safe to call on a nil *TemplateReloader.
Example ¶
package main
import (
"fmt"
"html/template"
"github.com/linkdata/jaws/lib/templatereloader"
)
func main() {
tmpl := template.Must(template.New("index.html").Parse("ok"))
lookuper, ok := any(tmpl).(interface {
Lookup(string) *template.Template
})
if !ok {
panic("template does not implement Lookup")
}
fmt.Println(lookuper.Lookup("index.html") != nil)
var reloader *templatereloader.TemplateReloader
fmt.Println(reloader.LastError())
}
Output: true <nil>
func (*TemplateReloader) Lookup ¶
func (tr *TemplateReloader) Lookup(name string) *template.Template
Lookup returns the named template, reparsing the templates from disk first when more than one second has passed since the last reload.
If a reload fails to parse (for example while a template file is being edited), the last successfully parsed templates are retained and used, so a transient parse error does not take down a running server. Lookup never panics on a reload error.
A failed reload still advances the reload timestamp, so the next reparse is deferred until the interval elapses again; the last-good templates keep being served meanwhile, and a fix made within that window is not picked up until the window reopens.
func (*TemplateReloader) Path ¶
func (tr *TemplateReloader) Path() (s string)
Path returns the glob pattern templates are reparsed from.
It is safe to call on a nil *TemplateReloader, in which case it returns "".
Source Files