To build your backend with Golang, you can use the go-partial library.

Most of the functionality is tailored to work seamlessly with the partial.js library.

However, it also integrates well with various frontend libraries, including:

• HTMX
• Turbo
• Stimulus
• Unpoly

To get started, install the go-partial library by running the following command:

go get github.com/partial-coffee/go-partial

After installing the library, import it into your project:

import "github.com/partial-coffee/go-partial"

Here is an example of how to use the library to handle a 404 error, wrapped by a general layout:

func (a *App) Handle404(w http.ResponseWriter, r *http.Request) {
    ctx := r.Context()
    l := a.BaseLayout()

    // Get the partial template
    fourOFour := partial.New(path.Join("templates", "404.gohtml")).ID("content")

    // If targeting a specific element, use the target header to get the ID
    if r.Header.Get(l.Connector().GetTargetHeader()) != "" {
        fourOFour.ID(r.Header.Get(l.Connector().GetTargetHeader()))
    }

    // Set the partial to the main layout
    l.Set(fourOFour)

    // Write the response
    err := l.WriteWithRequest(ctx, w, r)
    if err != nil {
        a.Logger.Error("failed to write response", err.Error())
    }
}

That's it! You now have a working 404 page that can be used to show a 404 error in a specific target or when browsing to an invalid path.