[FLINK-10229][Sql Client] Support listing of views

docs/dev/table/sqlClient.md

@@ -504,6 +504,12 @@ Views created within a CLI session can also be removed again using the `DROP VIE
 DROP VIEW MyNewView;
 {% endhighlight %}
 
+Displays all of the views in the current session using the `SHOW VIEWS` statement:
+
+{% highlight text %}
+SHOW VIEWS
+{% endhighlight %}
+
 <span class="label label-danger">Attention</span> The definition of views in the CLI is limited to the mentioned syntax above. Defining a schema for views or escaping whitespaces in table names will be supported in future versions.
 
 {% top %}

flink-table/flink-sql-client/src/main/java/org/apache/flink/table/client/cli/CliClient.java

@@ -266,6 +266,9 @@ private void callCommand(SqlCommandCall cmdCall) {
 			case SHOW_TABLES:
 				callShowTables();
 				break;
+			case SHOW_VIEWS:
+				callShowViews();
+				break;
 			case SHOW_FUNCTIONS:
 				callShowFunctions();
 				break;
@@ -359,6 +362,23 @@ private void callShowTables() {
 		terminal.flush();
 	}
 
+	private void callShowViews() {
+		final List<String> views;
+		try {
+			views = executor.listViews(context);
+		} catch (SqlExecutionException e) {
+			printExecutionException(e);
+			return;
+		}
+
+		if (views.isEmpty()) {
+			terminal.writer().println(CliStrings.messageInfo(CliStrings.MESSAGE_EMPTY).toAnsi());
+		} else {
+			views.forEach((v) -> terminal.writer().println(v));
+		}
+		terminal.flush();
+	}
+
 	private void callShowFunctions() {
 		final List<String> functions;
 		try {

flink-table/flink-sql-client/src/main/java/org/apache/flink/table/client/cli/CliStrings.java

@@ -45,6 +45,7 @@ private CliStrings() {
 		.append(formatCommand(SqlCommand.CLEAR, "Clears the current terminal."))
 		.append(formatCommand(SqlCommand.HELP, "Prints the available commands."))
 		.append(formatCommand(SqlCommand.SHOW_TABLES, "Shows all registered tables."))
+		.append(formatCommand(SqlCommand.SHOW_VIEWS, "Shows all registered views."))
 		.append(formatCommand(SqlCommand.SHOW_FUNCTIONS, "Shows all registered user-defined functions."))
 		.append(formatCommand(SqlCommand.DESCRIBE, "Describes the schema of a table with the given name."))
 		.append(formatCommand(SqlCommand.EXPLAIN, "Describes the execution plan of a query or table with the given name."))

flink-table/flink-sql-client/src/main/java/org/apache/flink/table/client/cli/SqlCommandParser.java

@@ -87,6 +87,10 @@ enum SqlCommand {
 			"SHOW\\s+TABLES",
 			NO_OPERANDS),
 
+		SHOW_VIEWS(
+			"SHOW\\s+VIEWS",
+			NO_OPERANDS),
+
 		SHOW_FUNCTIONS(
 			"SHOW\\s+FUNCTIONS",
 			NO_OPERANDS),

flink-table/flink-sql-client/src/main/java/org/apache/flink/table/client/gateway/Executor.java

@@ -45,6 +45,11 @@ public interface Executor {
 	 */
 	List<String> listTables(SessionContext session) throws SqlExecutionException;
 
+	/**
+	 * Lists all views known to the executor.
+	 */
+	List<String> listViews(SessionContext session) throws SqlExecutionException;
+
 	/**
 	 * Lists all user-defined functions known to the executor.
 	 */

flink-table/flink-sql-client/src/main/java/org/apache/flink/table/client/gateway/local/LocalExecutor.java

@@ -199,6 +199,17 @@ public List<String> listTables(SessionContext session) throws SqlExecutionExcept
 		return Arrays.asList(tableEnv.listTables());
 	}
 
+	@Override
+	public List<String> listViews(SessionContext session) throws SqlExecutionException {
+		List<String> viewList = new ArrayList<>();
+		session.getViews().keySet().forEach((viewName) -> viewList.add(viewName));
+
+		//sort
+		Collections.sort(viewList);
+
+		return viewList;
+	}
+
 	@Override
 	public List<String> listUserDefinedFunctions(SessionContext session) throws SqlExecutionException {
 		final TableEnvironment tableEnv = getOrCreateExecutionContext(session)

flink-table/flink-sql-client/src/test/java/org/apache/flink/table/client/cli/CliClientTest.java

@@ -163,6 +163,11 @@ public List<String> listTables(SessionContext session) throws SqlExecutionExcept
 			return null;
 		}
 
+		@Override
+		public List<String> listViews(SessionContext session) throws SqlExecutionException {
+			return null;
+		}
+
 		@Override
 		public List<String> listUserDefinedFunctions(SessionContext session) throws SqlExecutionException {
 			return null;

flink-table/flink-sql-client/src/test/java/org/apache/flink/table/client/cli/CliResultViewTest.java

@@ -130,6 +130,11 @@ public List<String> listTables(SessionContext session) throws SqlExecutionExcept
 			return null;
 		}
 
+		@Override
+		public List<String> listViews(SessionContext session) throws SqlExecutionException {
+			return null;
+		}
+
 		@Override
 		public List<String> listUserDefinedFunctions(SessionContext session) throws SqlExecutionException {
 			return null;

flink-table/flink-sql-client/src/test/java/org/apache/flink/table/client/cli/SqlCommandParserTest.java

@@ -40,6 +40,8 @@ public void testCommands() {
 		testValidSqlCommand("CLEAR", new SqlCommandCall(SqlCommand.CLEAR));
 		testValidSqlCommand("SHOW TABLES", new SqlCommandCall(SqlCommand.SHOW_TABLES));
 		testValidSqlCommand("  SHOW   TABLES   ", new SqlCommandCall(SqlCommand.SHOW_TABLES));
+		testValidSqlCommand("SHOW VIEWS", new SqlCommandCall(SqlCommand.SHOW_VIEWS));
+		testValidSqlCommand("	SHOW   VIEWS", new SqlCommandCall(SqlCommand.SHOW_VIEWS));
 		testValidSqlCommand("SHOW FUNCTIONS", new SqlCommandCall(SqlCommand.SHOW_FUNCTIONS));
 		testValidSqlCommand("  SHOW    FUNCTIONS   ", new SqlCommandCall(SqlCommand.SHOW_FUNCTIONS));
 		testValidSqlCommand("DESCRIBE MyTable", new SqlCommandCall(SqlCommand.DESCRIBE, new String[]{"MyTable"}));

flink-table/flink-sql-client/src/test/java/org/apache/flink/table/client/gateway/local/LocalExecutorITCase.java

@@ -149,6 +149,26 @@ public void testValidateSession() throws Exception {
 		assertEquals(expectedTables, actualTables);
 	}
 
+	@Test
+	public void testListViews() throws Exception {
+		final Executor executor = createDefaultExecutor(clusterClient);
+		final SessionContext session = new SessionContext("test-session", new Environment());
+
+		session.addView(ViewEntry.create("TestView3", "SELECT 1"));
+		session.addView(ViewEntry.create("MyView1", "SELECT 1"));
+		session.addView(ViewEntry.create("aView1", "SELECT 1"));
+
+		final List<String> actualViews = executor.listViews(session);
+		final List<String> expectedViews = Arrays.asList(
+			"MyView1",
+			"TestView1",
+			"TestView2",
+			"TestView3",
+			"aView1");
+
+		assertEquals(expectedViews, actualViews);
+	}
+
 	@Test
 	public void testListTables() throws Exception {
 		final Executor executor = createDefaultExecutor(clusterClient);