Implement transactions (#30)

* Implement transactions

* Add executeStatement with param setter

---------

Co-authored-by: kaklakariada <[email protected]>

CHANGELOG.md

@@ -6,11 +6,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [0.9.0] - unreleased
 
-## [0.8.0] - 2024-10-20
+## [0.8.0] - 2024-11-03
 
 - [PR #27](https://github.com/itsallcode/simple-jdbc/pull/27): Update dependencies
 - [PR #28](https://github.com/itsallcode/simple-jdbc/pull/28): Refactored batch inserts (**Breaking change**)
 - [PR #29](https://github.com/itsallcode/simple-jdbc/pull/29): Setting values for a `PreparedStatement` (**Breaking change**)
+- [PR #30](https://github.com/itsallcode/simple-jdbc/pull/30): Add transaction support
 
 ## [0.7.1] - 2024-09-01
 

src/main/java/org/itsallcode/jdbc/DbOperations.java

@@ -0,0 +1,86 @@
+package org.itsallcode.jdbc;
+
+import static java.util.function.Predicate.not;
+
+import java.util.Arrays;
+
+import org.itsallcode.jdbc.resultset.RowMapper;
+import org.itsallcode.jdbc.resultset.SimpleResultSet;
+import org.itsallcode.jdbc.resultset.generic.Row;
+
+/**
+ * Interface for various DB operations.
+ */
+public interface DbOperations extends AutoCloseable {
+    /**
+     * Execute all commands in a SQL script, separated with {@code ;}.
+     * 
+     * @param sqlScript the script to execute.
+     */
+    default void executeScript(final String sqlScript) {
+        Arrays.stream(sqlScript.split(";"))
+                .map(String::trim)
+                .filter(not(String::isEmpty))
+                .forEach(this::executeStatement);
+    }
+
+    /**
+     * Execute a single SQL statement.
+     * 
+     * @param sql                     the statement
+     * @param preparedStatementSetter prepared statement setter
+     */
+    void executeStatement(final String sql, PreparedStatementSetter preparedStatementSetter);
+
+    /**
+     * Execute a single SQL statement.
+     * 
+     * @param sql the statement
+     */
+    void executeStatement(final String sql);
+
+    /**
+     * Execute a SQL query and return a {@link SimpleResultSet result set} with
+     * generic {@link Row}s.
+     * 
+     * @param sql the query
+     * @return the result set
+     */
+    SimpleResultSet<Row> query(final String sql);
+
+    /**
+     * Execute a SQL query and return a {@link SimpleResultSet result set} with rows
+     * converted to a custom type {@link T}.
+     * 
+     * @param <T>       generic row type
+     * @param sql       SQL query
+     * @param rowMapper row mapper
+     * @return the result set
+     */
+    <T> SimpleResultSet<T> query(final String sql, final RowMapper<T> rowMapper);
+
+    /**
+     * Execute a SQL query, set parameters and return a {@link SimpleResultSet
+     * result set} with rows converted to a custom type {@link T}.
+     * 
+     * @param <T>                     generic row type
+     * @param sql                     SQL query
+     * @param preparedStatementSetter the prepared statement setter
+     * @param rowMapper               row mapper
+     * @return the result set
+     */
+    <T> SimpleResultSet<T> query(final String sql, final PreparedStatementSetter preparedStatementSetter,
+            final RowMapper<T> rowMapper);
+
+    /**
+     * Create a batch insert builder
+     * 
+     * @param rowType row type
+     * @param <T>     row type
+     * @return batch insert builder
+     */
+    <T> BatchInsertBuilder<T> batchInsert(final Class<T> rowType);
+
+    @Override
+    void close();
+}

src/main/java/org/itsallcode/jdbc/SimpleConnection.java

@@ -1,9 +1,6 @@
 package org.itsallcode.jdbc;
 
-import static java.util.function.Predicate.not;
-
 import java.sql.*;
-import java.util.Arrays;
 import java.util.Objects;
 import java.util.logging.Logger;
 
@@ -17,7 +14,7 @@
  * A simplified version of a JDBC {@link Connection}. Create new connections
  * with {@link ConnectionFactory#create(String, String, String)}.
  */
-public class SimpleConnection implements AutoCloseable {
+public class SimpleConnection implements DbOperations {
     private static final Logger LOG = Logger.getLogger(SimpleConnection.class.getName());
 
     private final Connection connection;
@@ -33,65 +30,40 @@ public class SimpleConnection implements AutoCloseable {
     }
 
     /**
-     * Execute all commands in a SQL script, separated with {@code ;}.
+     * Start a new transaction by disabling auto commit.
      * 
-     * @param sqlScript the script to execute.
+     * @return a new, running transaction.
      */
-    public void executeScript(final String sqlScript) {
-        Arrays.stream(sqlScript.split(";"))
-                .map(String::trim)
-                .filter(not(String::isEmpty))
-                .forEach(this::executeStatement);
+    public Transaction startTransaction() {
+        return Transaction.start(this);
     }
 
-    /**
-     * Execute a single SQL statement.
-     * 
-     * @param sql the statement
-     */
+    @Override
     public void executeStatement(final String sql) {
-        try (Statement statement = connection.createStatement()) {
-            statement.execute(sql);
-        } catch (final SQLException e) {
-            throw new UncheckedSQLException("Error executing '" + sql + "'", e);
+        this.executeStatement(sql, stmt -> {
+        });
+    }
+
+    @Override
+    public void executeStatement(final String sql, final PreparedStatementSetter preparedStatementSetter) {
+        try (SimplePreparedStatement statement = prepareStatement(sql)) {
+            statement.setValues(preparedStatementSetter);
+            statement.execute();
         }
     }
 
-    /**
-     * Execute a SQL query and return a {@link SimpleResultSet result set} with
-     * generic {@link Row}s.
-     * 
-     * @param sql the query
-     * @return the result set
-     */
+    @Override
     public SimpleResultSet<Row> query(final String sql) {
         return query(sql, ContextRowMapper.generic(dialect));
     }
 
-    /**
-     * Execute a SQL query and return a {@link SimpleResultSet result set} with rows
-     * converted to a custom type {@link T}.
-     * 
-     * @param <T>       generic row type
-     * @param sql       SQL query
-     * @param rowMapper row mapper
-     * @return the result set
-     */
+    @Override
     public <T> SimpleResultSet<T> query(final String sql, final RowMapper<T> rowMapper) {
         return query(sql, ps -> {
         }, rowMapper);
     }
 
-    /**
-     * Execute a SQL query, set parameters and return a {@link SimpleResultSet
-     * result set} with rows converted to a custom type {@link T}.
-     * 
-     * @param <T>                     generic row type
-     * @param sql                     SQL query
-     * @param preparedStatementSetter the prepared statement setter
-     * @param rowMapper               row mapper
-     * @return the result set
-     */
+    @Override
     public <T> SimpleResultSet<T> query(final String sql, final PreparedStatementSetter preparedStatementSetter,
             final RowMapper<T> rowMapper) {
         LOG.finest(() -> "Executing query '" + sql + "'...");
@@ -108,13 +80,7 @@ private PreparedStatement wrap(final PreparedStatement preparedStatement) {
         return new ConvertingPreparedStatement(preparedStatement, paramSetterProvider);
     }
 
-    /**
-     * Create a batch insert builder
-     * 
-     * @param rowType row type
-     * @param <T>     row type
-     * @return batch insert builder
-     */
+    @Override
     public <T> BatchInsertBuilder<T> batchInsert(final Class<T> rowType) {
         return new BatchInsertBuilder<>(this::prepareStatement);
     }
@@ -127,13 +93,28 @@ private PreparedStatement prepare(final String sql) {
         }
     }
 
-    /**
-     * Database dialect of this connection.
-     * 
-     * @return dialect
-     */
-    public DbDialect getDialect() {
-        return dialect;
+    void setAutoCommit(final boolean autoCommit) {
+        try {
+            this.connection.setAutoCommit(autoCommit);
+        } catch (final SQLException e) {
+            throw new UncheckedSQLException("Failed to set autoCommit to " + autoCommit, e);
+        }
+    }
+
+    void rollback() {
+        try {
+            this.connection.rollback();
+        } catch (final SQLException e) {
+            throw new UncheckedSQLException("Failed to rollback transaction", e);
+        }
+    }
+
+    void commit() {
+        try {
+            this.connection.commit();
+        } catch (final SQLException e) {
+            throw new UncheckedSQLException("Failed to commit transaction", e);
+        }
     }
 
     @Override

src/main/java/org/itsallcode/jdbc/SimplePreparedStatement.java

@@ -20,19 +20,27 @@ class SimplePreparedStatement implements AutoCloseable {
     }
 
     <T> SimpleResultSet<T> executeQuery(final ContextRowMapper<T> rowMapper) {
-        final ResultSet resultSet = doExecute();
+        final ResultSet resultSet = doExecuteQuery();
         final ResultSet convertingResultSet = ConvertingResultSet.create(dialect, resultSet);
         return new SimpleResultSet<>(context, convertingResultSet, rowMapper);
     }
 
-    private ResultSet doExecute() {
+    private ResultSet doExecuteQuery() {
         try {
             return statement.executeQuery();
         } catch (final SQLException e) {
             throw new UncheckedSQLException("Error executing query '" + sql + "'", e);
         }
     }
 
+    boolean execute() {
+        try {
+            return statement.execute();
+        } catch (final SQLException e) {
+            throw new UncheckedSQLException("Error executing statement '" + sql + "'", e);
+        }
+    }
+
     @Override
     public void close() {
         try {

src/main/java/org/itsallcode/jdbc/Transaction.java

@@ -0,0 +1,84 @@
+package org.itsallcode.jdbc;
+
+import org.itsallcode.jdbc.resultset.RowMapper;
+import org.itsallcode.jdbc.resultset.SimpleResultSet;
+import org.itsallcode.jdbc.resultset.generic.Row;
+
+/**
+ * A running database transaction. The transaction will be rolled back
+ * automatically in {@link #close()}.
+ */
+public final class Transaction implements DbOperations {
+
+    private final SimpleConnection connection;
+
+    private Transaction(final SimpleConnection connection) {
+        this.connection = connection;
+    }
+
+    static Transaction start(final SimpleConnection connection) {
+        connection.setAutoCommit(false);
+        return new Transaction(connection);
+    }
+
+    /**
+     * Commit the transaction.
+     */
+    public void commit() {
+        connection.commit();
+    }
+
+    /**
+     * Rollback the transaction.
+     */
+    public void rollback() {
+        connection.rollback();
+    }
+
+    @Override
+    public void executeStatement(final String sql) {
+        connection.executeStatement(sql);
+    }
+
+    @Override
+    public void executeStatement(final String sql, final PreparedStatementSetter preparedStatementSetter) {
+        connection.executeStatement(sql, preparedStatementSetter);
+    }
+
+    @Override
+    public SimpleResultSet<Row> query(final String sql) {
+        return connection.query(sql);
+    }
+
+    @Override
+    public void executeScript(final String sqlScript) {
+        connection.executeScript(sqlScript);
+    }
+
+    @Override
+    public <T> SimpleResultSet<T> query(final String sql, final RowMapper<T> rowMapper) {
+        return connection.query(sql, rowMapper);
+    }
+
+    @Override
+    public <T> SimpleResultSet<T> query(final String sql, final PreparedStatementSetter preparedStatementSetter,
+            final RowMapper<T> rowMapper) {
+        return connection.query(sql, preparedStatementSetter, rowMapper);
+    }
+
+    @Override
+    public <T> BatchInsertBuilder<T> batchInsert(final Class<T> rowType) {
+        return connection.batchInsert(rowType);
+    }
+
+    /**
+     * Rollback transaction and enable auto commit.
+     * <p>
+     * Explicitly run {@link #commit()} before to commit your transaction.
+     */
+    @Override
+    public void close() {
+        this.rollback();
+        connection.setAutoCommit(true);
+    }
+}

src/main/java/org/itsallcode/jdbc/resultset/SimpleResultSet.java

@@ -54,7 +54,9 @@ public Iterator<T> iterator() {
      * @return a list with all rows.
      */
     public List<T> toList() {
-        return stream().toList();
+        try (Stream<T> stream = stream()) {
+            return stream.toList();
+        }
     }
 
     /**
@@ -106,7 +108,7 @@ private ResultSetIterator(final Context context, final SimpleResultSet<T> simple
             this.hasNext = hasNext;
         }
 
-        public static <T> Iterator<T> create(final Context context, final SimpleResultSet<T> simpleResultSet,
+        private static <T> Iterator<T> create(final Context context, final SimpleResultSet<T> simpleResultSet,
                 final ContextRowMapper<T> rowMapper) {
             final boolean firstRowExists = simpleResultSet.next();
             return new ResultSetIterator<>(context, simpleResultSet, rowMapper, firstRowExists);