如何加载和缓存100页的模板页面，以及呈现正确的模板并返回处理程序

I have 100's of templates that I need to use in a web application.

Is there a way to parse them once and re-use them as oppose to loading them for each request?

Assume for now that the templates don't take in a model, they are simply static templates (to make it simpler).

The templates are stored in the below folder structure, so based on the theme variable I will know where to get the template from.

/views/{theme}/index.tmpl

So my hanlder so far is like this:

func RenderPage(w http.ResponseWriter, r *http.Request) {

   var theme := // set template theme based on some condition

}

How can I preload all the templates, and then somehow fetch the correct one and render it to the browser in this handler?

You could do something like the following, load a map who's index is the Template name declared in the template by {{ define "Name" }}, and who's value is an array of files to parse. Then loop through that map and use those values to create a *template.Template and store that in a global map whose index is the template name and the value is the *template.Template value.

Then figure out which template you need, grab it from the map and execute it.

package main

import (
    "html/template"
    "log"
    "net/http"
)

var templates map[string]*template.Template

func main() {
    templates = make(map[string]*template.Template)
    var template = make(map[string][]string)
    template["Home"] = []string{"home.html"}
    template["About"] = []string{"about.html"}
    template["404"] = []string{"404.html"}
    // Obviously you'd automate this ^
    loadAllTemplates(&template, templates)
    http.HandleFunc("/", renderCorrectTemplate)
    http.ListenAndServe(":8080", nil)
}

func loadAllTemplates(templateMap *map[string][]string, templates map[string]*template.Template) {
    for name, files := range *templateMap {
        t, err := template.New(name).ParseFiles(files...)
        if err != nil {
            log.Printf("Error Parsing Template: %s", err.Error())
            return
        }
        templates[name] = t
    }
}

func renderCorrectTemplate(w http.ResponseWriter, r *http.Request) {
    // This function would be different for you because you're not using GET, this is just an example.
    r.ParseForm()
    log.Println(r.URL.Query().Get("template"))
    switch r.URL.Query().Get("template") {
    case "Home":
        //Gather Needed Data
        err := templates["Home"].Execute(w, data)
        //Handle err
    case "About":
        //Gather Needed Data
        err := templates["About"].Execute(w, data)
        //Handle err
    default:
        err := templates["404"].Execute(w, data)
        //Handle err
    }
}