My go app that uses embed with wildcard fails to build

[daisukixci]

Hi,

I started using Wails for an application, but I have an issue regarding embedding files (others than the static for the webapp) when there is a wildcard in the embed directive.

My tree looks like

❯ tree  backend/check
backend/check
├── checks
│   └── dummy
│       └── check.json
│       └── check.sh
├── fs.go
...

fs.go contains

package check

import (
	"embed"
...
)

//go:embed checks/*/check.json
var checksF embed.FS

//go:embed checks/*
var dataF embed.FS
...

When trying to run wails dev, I get

❯ wails dev
Wails CLI v2.5.1

Executing: go mod tidy
  • Generating bindings:

  ERROR
          backend/check/fs.go:15:12: pattern checks/*: cannot embed directory checks/*: invalid name *

          exit status 1
 ♥   If Wails is useful to you or your company, please consider sponsoring the project:
https://github.com/sponsors/leaanthony

And I see that backend/check/checks/*/ is created and contains:

tree backend/check/checks/\*
backend/check/checks/*
└── check.json
    └── gitkeep

1 directory, 1 file

Am I doing something wrong ? Could it be a bug ? I feel like it is related to the wildcard usage as when removed it does work

Thanks for time and help

[BillBuilt]

I encountered this problem awhile ago too. My Wails app had sat for several months and when I came back to it after updating all of my dependencies, including Wails, the wildcard stopped working. I was able to get around it but it is certainly undesired.

[daisukixci]

Building without Wails works though

[BillBuilt]

We use wildcard embeds at my employment: //go:embed mappings/*.json and it works fine with Go 1.20.7 (just Go, no Wails).

Plenty of references about using wildcards and other patterns in the Go docs: https://pkg.go.dev/embed

Many of their examples show using wildcards:

package main

import (
	"embed"
	"log"
	"net/http"
)

//go:embed internal/embedtest/testdata/*.txt
var content embed.FS

func main() {
	mutex := http.NewServeMux()
	mutex.Handle("/", http.FileServer(http.FS(content)))
	err := http.ListenAndServe(":8080", mutex)
	if err != nil {
		log.Fatal(err)
	}
}

[leaanthony]

Building without Wails works though

This is literally a Go only directive and has nothing to do with Wails.

[stffabi]

@leaanthony I suspect the problem is due to our code that makes sure the embed directories exist. So in this case //go:embed checks/* we create a directory structure like this checks/*/.gitkeep. And embedding a folder or file with name * is invalid. That's why the go build will then fail with: invalid name *

[leaanthony]

Ah that makes a ton more sense 😕