VSCode create unsaved file and add content - visual-studio-code

Question

In VS Code I would like to create a new document in a new editor (same window), but it need to remain unsaved. I cannot find a way to programmatically set the content of this document while it is in a unsaved state.
I have used:
commands.executeCommand("workbench.action.files.newUntitledFile")
but there seems to be no way to then add content to the file.
When I create a new temporary file and open it with:
workspace.openTextDocument(path)
The file is already saved.
Any thoughts?

Answer 1

Try using openTextDocument with an untitled document to create a unsaved file at a given path, and then use WorkspaceEdit to add some text:
import * as vscode from 'vscode';
import * as path from 'path';
const newFile = vscode.Uri.parse('untitled:' + path.join(vscode.workspace.rootPath, 'safsa.txt'));
vscode.workspace.openTextDocument(newFile).then(document => {
const edit = new vscode.WorkspaceEdit();
edit.insert(newFile, new vscode.Position(0, 0), "Hello world!");
return vscode.workspace.applyEdit(edit).then(success => {
if (success) {
vscode.window.showTextDocument(document);
} else {
vscode.window.showInformationMessage('Error!');
}
});
});
The new file will be unsaved when first opened, but saved to the given path when a user saves it.
Hope that provides a good starting point.

Answer 2

I don't know how to open it in the editor, but you can create an unsaved file with content like the following:
vscode.workspace.openTextDocument({
content: "your content",
language: "text"
});

Answer 3

That should be supported in VSCode 1.54 (Feb. 2021), meaning the vscode.workspace.openTextDocument script from Matt is implemented by default:
Open Editors New Untitled File action
We have introduced a New Untitled File action in the Open Editors view title area.

Answer 4

I was having some issues when the document was eventually saved using this solution from Matt, but I was able to use it in combination with DarkTrick's response.
By using the default behavior of creating an empty document and making it active in the then clause.
vscode.workspace.openTextDocument({
content: newXmlContent,
language: "xml"
}).then(newDocument => {
vscode.window.showTextDocument(newDocument);
});
This allows me to create an untitled document with any content I want and show it in the editor. I was not able to give it a specific name though. This might be a limitation of creating an untitled document.