VSCode Extension: How to open a file if no workspace folders are available?

Question

I've been working on an extension that allows adding files with pre-defined content and modifying them using a custom web editor. The custom command "Add new XXX file" looks like the following:

    let disposable = vscode.commands.registerCommand('myextension.add-new-file', () => {
    if(vscode.workspace.workspaceFolders?.length){
        const rootPath = vscode.workspace.workspaceFolders[0].uri.fsPath ;
        let counter = 0;
        let filePath = '';
        do{
            counter++;
            filePath = path.join(rootPath, `NewFile${counter}.my-ext`);
        }while(fs.existsSync(filePath));
        fs.writeFileSync(filePath, JSON.stringify(newFileContent), 'utf8');
        const openPath = vscode.Uri.file(filePath); 
        vscode.commands.executeCommand('vscode.openWith', openPath, 'myextension.custom-designer');                 
    }
});

It works OK if a folder is opened in VS Code. However, if no folder is opened, the rootPath can't be resolved. What's the solution for such a scenario? Does the 'vscode.openWith' accept the file content instead of the path to open?

Answer 1

You can accomplish your goal using the untitled scheme:

vscode.commands.executeCommand(
  'vscode.openWith',
  vscode.Uri.parse("untitled:FooBar"),
  'myextension.custom-designer',
);

You can change your custom editor so that it detects when empty document gets passed to it and replaces the empty document with newFileContent.