chore: playground will also autocomplete collection names for default…

… connected db

src/connectionController.ts

@@ -1122,4 +1122,17 @@ export default class ConnectionController {
       selectedQuickPickItem.data.connectionId
     );
   }
+
+  getActiveConnectionDefaultDB(): string | null {
+    try {
+      const connectionString = new ConnectionString(
+        this.getActiveConnectionString()
+      );
+      return connectionString.pathname !== '/'
+        ? connectionString.pathname.substring(1)
+        : null;
+    } catch {
+      return null;
+    }
+  }
 }

src/language/mongoDBService.ts

@@ -14,6 +14,7 @@ import type {
   MarkupContent,
   Diagnostic,
 } from 'vscode-languageserver/node';
+import ConnectionString from 'mongodb-connection-string-url';
 import { CliServiceProvider } from '@mongosh/service-provider-server';
 import type { Document } from '@mongosh/service-provider-core';
 import { getFilteredCompletions } from '@mongodb-js/mongodb-constants';
@@ -35,7 +36,7 @@ import type {
 } from '../types/playgroundType';
 import type { ClearCompletionsCache } from '../types/completionsCache';
 import { Visitor } from './visitor';
-import type { CompletionState } from './visitor';
+import type { CompletionState, NamespaceState } from './visitor';
 import LINKS from '../utils/links';
 
 import DIAGNOSTIC_CODES from './diagnosticCodes';
@@ -96,6 +97,16 @@ export default class MongoDBService {
     return this._currentConnectionOptions;
   }
 
+  get defaultConnectedDB(): string | null {
+    if (!this.connectionString) {
+      return null;
+    }
+    const connectionString = new ConnectionString(this.connectionString);
+    return connectionString.pathname !== '/'
+      ? connectionString.pathname.substring(1)
+      : null;
+  }
+
   initialize({
     extensionPath,
     connectionId,
@@ -445,6 +456,22 @@ export default class MongoDBService {
     return /^(?![0-9])[a-zA-Z0-9$_]+$/.test(str);
   }
 
+  /**
+   * @param state  The state returned from Visitor.
+   * @returns The state with the default connected database, if available, if
+   * and only if the state returned from visitor does not already mention a
+   * database
+   */
+  withDefaultDatabase<T extends NamespaceState | CompletionState>(state: T): T {
+    if (state.databaseName === null && this.defaultConnectedDB !== null) {
+      return {
+        ...state,
+        databaseName: this.defaultConnectedDB,
+      };
+    }
+    return state;
+  }
+
   /**
    * Parse code from a playground to identify
    * a context in which export to language action is being called.
@@ -473,7 +500,9 @@ export default class MongoDBService {
     params: PlaygroundTextAndSelection
   ): ExportToLanguageNamespace {
     try {
-      const state = this._visitor.parseASTForNamespace(params);
+      const state = this.withDefaultDatabase(
+        this._visitor.parseASTForNamespace(params)
+      );
       return {
         databaseName: state.databaseName,
         collectionName: state.collectionName,
@@ -917,9 +946,8 @@ export default class MongoDBService {
       `Provide completion items for a position: ${util.inspect(position)}`
     );
 
-    const state = this._visitor.parseASTForCompletion(
-      document?.getText(),
-      position
+    const state = this.withDefaultDatabase(
+      this._visitor.parseASTForCompletion(document?.getText(), position)
     );
     this._connection.console.log(
       `VISITOR completion state: ${util.inspect(state)}`

src/test/suite/connectionController.test.ts

@@ -30,6 +30,7 @@ import {
   TEST_DATABASE_URI_USER,
   TEST_USER_USERNAME,
   TEST_USER_PASSWORD,
+  TEST_DB_NAME,
 } from './dbTestHelper';
 import KeytarStub from './keytarStub';
 import { ext } from '../../extensionConstants';
@@ -1852,4 +1853,43 @@ suite('Connection Controller Test Suite', function () {
       ]);
     });
   });
+
+  suite('getActiveConnectionDefaultDB', () => {
+    suite('when connected to a connection and a default database', () => {
+      test('it should return the default connected database', async () => {
+        const succesfullyConnected =
+          await testConnectionController.addNewConnectionStringAndConnect(
+            `${TEST_DATABASE_URI}/${TEST_DB_NAME}`
+          );
+        assert.strictEqual(succesfullyConnected, true);
+        assert.strictEqual(
+          testConnectionController.getActiveConnectionDefaultDB(),
+          TEST_DB_NAME
+        );
+      });
+    });
+
+    suite('when connected to a connection without a default database', () => {
+      test('it should return the null', async () => {
+        const succesfullyConnected =
+          await testConnectionController.addNewConnectionStringAndConnect(
+            `${TEST_DATABASE_URI}`
+          );
+        assert.strictEqual(succesfullyConnected, true);
+        assert.strictEqual(
+          testConnectionController.getActiveConnectionDefaultDB(),
+          null
+        );
+      });
+    });
+
+    suite('when not connected to a connection', () => {
+      test('it should return the null', () => {
+        assert.strictEqual(
+          testConnectionController.getActiveConnectionDefaultDB(),
+          null
+        );
+      });
+    });
+  });
 });