Avalonia-ls

Simple standalone Language Server for Avalonia XAML files suitable to lightweight editors like neovim and helix with support for completions and xaml formatting via xaml styler

Installation

To install from source, dotnet-sdk-9.0 and just must be installed. Clone recursively and run just install recipe( .local/bin must be in your path)

git clone https://www.github.com/eugenenoble2005/avalonia-ls.git --recursive
cd avalonia-ls
just install

You can also install from the AUR

yay -S avalonia-ls-git

After installing, you need only configure your editor of choice:

Helix

[[language]]
name="xml"
scope="source.axaml"
injection-regex="axaml"
file-types=["axaml"]
language-servers=["avalonials"]
grammar="xml"
auto-format=false
formatter={command="xaml-styler",args=["--write-to-stdout" ,"--take-pipe"]}

Neovim

vim.api.nvim_create_autocmd({ 'BufEnter', 'BufWinEnter' }, {
	pattern = { "*.axaml" },
	callback = function(event)
		vim.lsp.start {
			name = "avalonia",
			cmd = { "avalonia-ls" },
			root_dir = vim.fn.getcwd(),
		}
	end
})
vim.filetype.add({
	extension = {
		axaml = "xml",
	},
})

Instructions

For completions to work on an avalonia project, you must generate metadata and build. If you install with just, an avalonia-solution-parser executable will be installed

cd my-avalonia-project
# you should run the following generally in the directory with your .csproj or .fsproj files
avalonia-solution-parser .
dotnet build

You need to run avalonia-solution-parser to generate metadata just once. Completions should work afterwards

PREVIEWER

You can run a xaml previewer in a browser tab for any xaml file in your project:

avalonia-previewer --file path/to/axaml/file

On supported terminal emulators like kitty, ghostty or wezterm, you can run the previewer directly inside the terminal. This is experimental and does not yet capture input like mouse and keyboard.

avalonia-previewer --file path/to/axaml/file --target terminal