Make users open a folder if no folder is open (#135)

https://user-images.githubusercontent.com/88345179/197787241-31d82aea-fa1c-4621-a60b-6b6c9b7d2cfe.mov

Author: kartikgupta-db

packages/databricks-vscode/package.json

@@ -203,7 +203,13 @@
         "viewsWelcome": [
             {
                 "view": "configurationView",
-                "contents": "In order to connect to a cluster you first have to configure your Databricks workspace:\n[Configure Databricks](command:databricks.connection.configureProject)\nTo learn more about how to use Databricks with VS Code [read our docs](https://github.com/databricks/databricks-vscode)."
+                "contents": "In order to connect to a cluster you first have to configure your Databricks workspace:\n[Configure Databricks](command:databricks.connection.configureProject)\nTo learn more about how to use Databricks with VS Code [read our docs](https://github.com/databricks/databricks-vscode).",
+                "when": "workspaceFolderCount > 0"
+            },
+            {
+                "view": "configurationView",
+                "contents": "Please open a folder to start using Databricks on VSCode.\n[Open Folder](command:vscode.openFolder)",
+                "when": "workspaceFolderCount == 0"
             }
         ],
         "menus": {

packages/databricks-vscode/src/extension.ts

@@ -30,7 +30,22 @@ import {
 import {format, loggers, transports} from "winston";
 import {UtilsCommands} from "./utils/UtilsCommands";
 
-export function activate(context: ExtensionContext): PublicApi {
+export function activate(context: ExtensionContext): PublicApi | undefined {
+    const a = workspace.workspaceFolders;
+    if (
+        workspace.workspaceFolders === undefined ||
+        workspace.workspaceFolders?.length === 0
+    ) {
+        window.showErrorMessage("Open a folder to use Databricks extension");
+        /*
+            We force the user to open a folder from the databricks sidebar view. Returning
+            here blocks all other commands from running. 
+            Since the workspace is reloaded when a folder is opened, the activation function
+            is called again. Therefore this won't block the activation of the extension on a
+            valid workspace.
+        */
+        return undefined;
+    }
     NamedLogger.getOrCreate(
         ExposedLoggers.SDK,
         {