Do not return null strings for DataGrip intro queries

build.gradle

@@ -2,7 +2,7 @@ plugins {
     id 'java'
 }
 
-version '1.3.2'
+version '1.3.3'
 
 sourceCompatibility = 1.8
 

driver/src/main/java/com/dbschema/CassandraBaseStatement.java

@@ -35,9 +35,9 @@ public boolean isClosed() {
         return isClosed;
     }
 
-    boolean executeInner(com.datastax.driver.core.ResultSet resultSet) throws SQLException {
+    boolean executeInner(com.datastax.driver.core.ResultSet resultSet, boolean returnNullStrings) throws SQLException {
         try {
-            result = new CassandraResultSet(this, resultSet);
+            result = new CassandraResultSet(this, resultSet, returnNullStrings);
             if (!result.isQuery()) {
                 result = null;
                 return false;

driver/src/main/java/com/dbschema/CassandraConnection.java

@@ -9,14 +9,29 @@
 import java.util.concurrent.Executor;
 
 public class CassandraConnection implements Connection {
+    /**
+     * This query retrieves Cassandra 2.x columns in DataGrip.
+     * <p>
+     * DataGrip before 2019.3 version assumes that index_name column does not contain null values.
+     * Driver since v1.3.2 version returns null value if a string is null (used to return "null")
+     * It means that DataGrip <2019.3 and driver v1.3.2 are incompatible.
+     * <p>
+     * To make driver and DG compatible driver will return "null" strings instead of null values
+     * for this particular query in PreparedStatement.
+     * See also https://youtrack.jetbrains.com/issue/DBE-9091
+     */
+    private static final String SELECT_COLUMNS_INTRO_QUERY = "SELECT column_name as name,\n       validator,\n       columnfamily_name as table_name,\n       type,\n       index_name,\n       index_options,\n       index_type,\n       component_index as position\nFROM system.schema_columns\nWHERE keyspace_name = ?";
+
     private final Session session;
     private CassandraJdbcDriver driver;
+    private boolean returnNullStringsFromIntroQuery;
     private boolean isClosed = false;
     private boolean isReadOnly = false;
 
-    CassandraConnection(Session session, CassandraJdbcDriver cassandraJdbcDriver) {
+    CassandraConnection(Session session, CassandraJdbcDriver cassandraJdbcDriver, boolean returnNullStringsFromIntroQuery) {
         this.session = session;
         driver = cassandraJdbcDriver;
+        this.returnNullStringsFromIntroQuery = returnNullStringsFromIntroQuery;
     }
 
     public String getCatalog() throws SQLException {
@@ -69,7 +84,7 @@ public Statement createStatement(int resultSetType, int resultSetConcurrency, in
     public PreparedStatement prepareStatement(String sql) throws SQLException {
         checkClosed();
         try {
-            return new CassandraPreparedStatement(session, session.prepare(sql));
+            return new CassandraPreparedStatement(session, session.prepare(sql), returnNullStringsFromIntroQuery || !SELECT_COLUMNS_INTRO_QUERY.equals(sql));
         } catch (Throwable t) {
             throw new SQLException(t.getMessage(), t);
         }

driver/src/main/java/com/dbschema/CassandraJdbcDriver.java

@@ -35,6 +35,8 @@
  */
 
 public class CassandraJdbcDriver implements Driver {
+    private static final String RETURN_NULL_STRINGS_FROM_INTRO_QUERY_KEY = "cassandra.jdbc.return.null.strings.from.intro.query";
+
     static {
         try {
             DriverManager.registerDriver(new CassandraJdbcDriver());
@@ -63,7 +65,8 @@ public Connection connect(String url, Properties info) throws SQLException {
                 } catch (NoHostAvailableException | AuthenticationException | IllegalStateException e) {
                     throw new SQLException(e.getMessage(), e);
                 }
-                return new CassandraConnection(session, this);
+                boolean returnNullStringsFromIntroQuery = Boolean.parseBoolean(info.getProperty(RETURN_NULL_STRINGS_FROM_INTRO_QUERY_KEY));
+                return new CassandraConnection(session, this, returnNullStringsFromIntroQuery);
             } catch (UnknownHostException e) {
                 throw new SQLException(e.getMessage(), e);
             }
@@ -116,7 +119,7 @@ public DriverPropertyInfo[] getPropertyInfo(String url, Properties info) {
     }
 
     String getVersion() {
-        return "1.3.2";
+        return "1.3.3";
     }
 
     @Override

driver/src/main/java/com/dbschema/CassandraPreparedStatement.java

@@ -10,6 +10,7 @@
 import java.math.BigDecimal;
 import java.net.URL;
 import java.sql.*;
+import java.util.Arrays;
 import java.util.Calendar;
 
 import static com.dbschema.DateUtil.Direction;
@@ -18,11 +19,13 @@
 public class CassandraPreparedStatement extends CassandraBaseStatement implements PreparedStatement {
 
     private final com.datastax.driver.core.PreparedStatement preparedStatement;
+    private final boolean returnNullStrings;
     private Object[] params;
 
-    CassandraPreparedStatement(Session session, final com.datastax.driver.core.PreparedStatement preparedStatement) {
+    CassandraPreparedStatement(Session session, final com.datastax.driver.core.PreparedStatement preparedStatement, boolean returnNullStrings) {
         super(session);
         this.preparedStatement = preparedStatement;
+        this.returnNullStrings = returnNullStrings;
     }
 
     @Override
@@ -64,7 +67,7 @@ public void clearBatch() throws SQLException {
     public int executeUpdate() throws SQLException {
         checkClosed();
         try {
-            result = new CassandraResultSet(this, session.execute(bindParameters()));
+            result = new CassandraResultSet(this, session.execute(bindParameters()), returnNullStrings);
             if (result.isQuery()) {
                 throw new SQLException("Not an update statement");
             }
@@ -241,7 +244,7 @@ public void setObject(int parameterIndex, Object x, int targetSqlType) throws SQ
     public boolean execute() throws SQLException {
         checkClosed();
         try {
-            return executeInner(session.execute(bindParameters()));
+            return executeInner(session.execute(bindParameters()), returnNullStrings);
         } catch (Throwable t) {
             throw new SQLException(t.getMessage(), t);
         }
@@ -257,9 +260,7 @@ private BoundStatement bindParameters() {
 
     private void clearParams() {
         if (params == null) return;
-        for (int i = 0; i < params.length; i++) {
-            params[i] = null;
-        }
+        Arrays.fill(params, null);
     }
 
     @Override

driver/src/main/java/com/dbschema/CassandraResultSet.java

@@ -14,10 +14,10 @@
 import java.nio.ByteBuffer;
 import java.sql.Date;
 import java.sql.*;
-import java.text.ParseException;
 import java.util.*;
 
-import static com.dbschema.DateUtil.*;
+import static com.dbschema.DateUtil.Direction;
+import static com.dbschema.DateUtil.considerTimeZone;
 
 public class CassandraResultSet implements ResultSet {
 
@@ -26,12 +26,18 @@ public class CassandraResultSet implements ResultSet {
     private final Statement statement;
     private final com.datastax.driver.core.ResultSet dsResultSet;
     private final Iterator<Row> iterator;
+    private final boolean returnNullStrings;
     private Row currentRow;
 
-    public CassandraResultSet(Statement statement, com.datastax.driver.core.ResultSet dsResultSet) {
+    CassandraResultSet(Statement statement, com.datastax.driver.core.ResultSet dsResultSet, boolean returnNullStrings) {
         this.statement = statement;
         this.dsResultSet = dsResultSet;
         this.iterator = dsResultSet.iterator();
+        this.returnNullStrings = returnNullStrings;
+    }
+
+    CassandraResultSet(Statement statement, com.datastax.driver.core.ResultSet dsResultSet) {
+        this(statement, dsResultSet, true);
     }
 
     @Override
@@ -70,11 +76,11 @@ public boolean wasNull() {
     @Override
     public String getString(int columnIndex) throws SQLException {
         checkClosed();
-        if (currentRow != null) {
-            Object object = currentRow.getObject(columnIndex - 1);
-            return object == null ? null : String.valueOf(object);
-        }
-        throw new SQLException("Exhausted ResultSet.");
+        if (currentRow == null) throw new SQLException("Exhausted ResultSet.");
+        Object o = currentRow.getObject(columnIndex - 1);
+        return o == null ?
+                returnNullStrings ? null : "" :
+                String.valueOf(o);
     }
 
     @Override

driver/src/main/java/com/dbschema/CassandraStatement.java

@@ -50,7 +50,7 @@ public int executeUpdate(String sql) throws SQLException {
     public boolean execute(String sql) throws SQLException {
         checkClosed();
         try {
-            return executeInner(session.execute(sql));
+            return executeInner(session.execute(sql), true);
         } catch (Throwable t) {
             throw new SQLException(t.getMessage(), t);
         }