preparations for styling: refactor template rendering #1
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@ -3,6 +3,7 @@ package controllers
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import (
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"fmt"
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"html/template"
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"log"
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"net/http"
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"officeHours/models"
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"os"
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@ -14,33 +15,45 @@ var funcs = template.FuncMap{
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}
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var baseTemplate = template.Must(template.ParseFiles("templates/base.html")).New("base.html").Funcs(funcs)
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// Execute a rendered full HTML page.
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//
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// If you just want to fill a template snippet, use the RawTemplates object.
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//
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// Parameters:
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// - name is the name of the template file inside templates/, without .html suffix.
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// - data is passed through to the template
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func (b *BaseHandler) serveTemplate(w http.ResponseWriter, name string, data any) {
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full_name := "templates/" + name + ".html"
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// check that template exists
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info, err := os.Stat(full_name)
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if (err != nil && os.IsNotExist(err)) || info.IsDir() {
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errMsg := fmt.Sprintf("Template %s nicht gefunden", full_name)
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johannes marked this conversation as resolved
Outdated
Gonne
commented
This could be an actual error using This could be an actual error using `fmt.Errorf`.
Furthermore I began logging in English. We should make that consistent.
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log.Println(errMsg)
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w.WriteHeader(http.StatusNotFound)
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johannes marked this conversation as resolved
Outdated
Gonne
commented
I think, that StatusNotFound is for user supplied references (e.g. a course or a room id), but this should be an internal server error. I think, that StatusNotFound is for user supplied references (e.g. a course or a room id), but this should be an internal server error.
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w.Write([]byte("404: Template nicht gefunden."))
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w.Write([]byte(errMsg))
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return
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}
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tmpl, err := baseTemplate.ParseFiles(full_name)
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Gonne
commented
Using this construction each template is parsed again and again, while it would be sufficient to parse them all on startup and later just execute them. Using this construction each template is parsed again and again, while it would be sufficient to parse them all on startup and later just execute them.
johannes
commented
Fixed (and spent too much time implementing this ^^) Fixed (and spent too much time implementing this ^^)
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if err != nil {
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// TODO: log.Printf
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errMsg := fmt.Sprintf("Template %s konnte nicht geparst werden : %s", full_name, err.Error())
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Gonne
commented
This could be an actual error using Furthermore error wrapping is something cool I just learnt. This could be an actual error using `fmt.Errorf`.
Furthermore I began logging in English. We should make that consistent.
Furthermore [error wrapping](https://blog.boot.dev/golang/wrapping-errors-in-go-how-to-handle-nested-errors/) is something cool I just learnt.
johannes
commented
Error wrapping looks nice. I started doing that. In general it seems best to wrap errors which occur during runtime from the beginning of a http request handler, which then logs the error and returns an error page to the user. (I added an inline TODO about that) Errors on startup however can just abort the whole program, like I implemented in Error wrapping looks nice. I started doing that.
In general it seems best to wrap errors which occur during runtime from the beginning of a http request handler, which then logs the error and returns an error page to the user. (I added an inline TODO about that)
Errors on startup however can just abort the whole program, like I implemented in `main.go`
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log.Println(errMsg)
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w.WriteHeader(http.StatusInternalServerError)
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w.Write([]byte(fmt.Sprintf("500: Template "+full_name+" konnte nicht geparst werden : %s", err.Error())))
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w.Write([]byte(errMsg))
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return
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}
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// TODO: cache templates in parsed state, but not executed
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err = template.Must(tmpl.Clone()).Execute(w, data)
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if err != nil {
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// TODO: log.Printf
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errMsg := fmt.Sprintf("Template %s konnte nicht ausgeführt werden : %s", full_name, err.Error())
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johannes marked this conversation as resolved
Outdated
Gonne
commented
This could be an actual error using Furthermore error wrapping is something cool I just learnt. This could be an actual error using `fmt.Errorf`.
Furthermore I began logging in English. We should make that consistent.
Furthermore [error wrapping](https://blog.boot.dev/golang/wrapping-errors-in-go-how-to-handle-nested-errors/) is something cool I just learnt.
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log.Println(errMsg)
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w.WriteHeader(http.StatusInternalServerError)
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w.Write([]byte(fmt.Sprintf("500: Template "+full_name+" konnte nicht ausgeführt werden : %s", err.Error())))
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w.Write([]byte(errMsg))
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return
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}
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}
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// standalone templates that should not be wrapped into the base.html
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var RawTemplates = template.Must(template.New("").Funcs(funcs).ParseFiles(
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"templates/confirmationMail",
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"templates/td.html",
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Here we should consider checking whether the name is restricted to something like
[a-zA-Z0-9]to prevent directory traversal. Possibly it is sufficient to forbid/and/or.This is not longer relevant, since all available templates are listed in one place inside our code and we do not parse filenames from anywhere else.