Learning go: day 13

2024-05-14 13:03:13 +01:00 · 2024-05-14 13:03:13 +01:00 · d410995778
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+---
+title: "Learning Go: Day Thirteen"
+date: 2024-05-15T08:00:00.0Z
+tags:
+    - learning
+    - go
+excerpt: "Creating some basic HTML output, and bundling static files"
+---
+
+So now I want to start working on putting together a basic interface. This post won't be about creating the interface itself, but instead just the ground work that will allow me to build it over the next post or two.
+
+## Creating some HTML output
+
+Alright, this was actually really straightforward. There's a module called [html/template](https://pkg.go.dev/html/template) that can be used to parse HTML, and includes a templating language.
+
+So I've created a super-simple HTML template at `templates/index.html`, and then use the `template.ParseFiles` function to parse and display it:
+
+```html
+<!-- templates/index.html -->
+
+<!DOCTYPE html>
+<html lang="en">
+    <head>
+        <title>Oopsie</title>
+    </head>
+    <body>
+        <h1>Oopsie uptime monitoring</h1>
+    </body>
+</html>
+```
+
+```go
+// main.go
+
+http.HandleFunc("GET /", func(w http.ResponseWriter, r *http.Request) {
+    pings := ping.ListGroupedBySite(db)
+
+    if _, err := json.Marshal(pings); err != nil {
+        w.Write([]byte(err.Error()))
+        w.WriteHeader(http.StatusInternalServerError)
+        return
+    } else {
+        w.Header().Set("Content-Type", "text/html")
+
+        t, _ := template.ParseFiles("templates/index.html")
+        t.Execute(w, nil)
+    }
+})
+```
+
+This works! But I can't deploy it, because when I compile the binary and upload it to my server it can't find the template files. Luckily, there's a package that can help me do that.
+
+## Bundling static files
+
+This part is basically magic. I have no idea how it works, but there is a package called [embed](https://pkg.go.dev/embed). I can use it to create an instance of `FS` with some bundled static content, and that then gets bundled into my binary, and it takes about 3 lines of code to do it 🤯.
+
+```go
+// main.go
+
+import (
+    "embed"
+)
+
+//go:embed templates/*
+var content embed.FS
+
+http.HandleFunc("GET /", func(w http.ResponseWriter, r *http.Request) {
+    pings := ping.ListGroupedBySite(db)
+
+    if _, err := json.Marshal(pings); err != nil {
+        w.Write([]byte(err.Error()))
+        w.WriteHeader(http.StatusInternalServerError)
+        return
+    } else {
+        w.Header().Set("Content-Type", "text/html")
+
+        t, _ := template.ParseFS(content, "templates/index.html")
+        t.Execute(w, nil)
+    }
+})
+```
+
+And then when I run `go build`, the resulting binary file has the HTML bundled in it and I can run it on my server. This is a _really_ powerful thing to have built directly into the standard library.
+
+So that's it for today, like I mentioned earlier, my next one or two posts will mostly be focused on making a UI.