feat: Add possibility to specify translator factories directly. (#568)

docs/src/main/asciidoc/modules/ROOT/pages/sql2cypher.adoc

@@ -14,13 +14,18 @@ The former is provided for two reasons: It allows us to distribute the driver wi
 
 Translators can be chained, and you can have as many translators on the classpath as you want.
 They will be ordered by a configurable precedence with our default implementation having the lowest precedence.
-Thus you can have for example a custom translator that takes care of a fixed set of queries, and if it cannot translate another, it will just be passed down to our implementation.
+Thus, you can have for example a custom translator that takes care of a fixed set of queries, and if it cannot translate another, it will just be passed down to our implementation.
 
 Translating arbitrary SQL queries to Cypher is an opinionated task as there is no right way to map table names to objects in the graph: A table name can be used as is as a label, you might want to transform it to a singular form etc. And then we haven't even started how to map relationships: Do you want to have relationship types derived from a join table, a join column (in that case, which one?) or the name of a foreign key?
 
 We made some assumptions that we find to match various use cases and instead of providing configuration and more code to cater for all scenarios, we offer the possibility to write your own translation layer.
 The driver will use the standard Java service loader mechanism to find an implementation of the SPI on the module- or classpath.
 
+NOTE: Some tools like Tableau use a class-loader that won't let the driver use the standard Java service loader mechanism.
+For these scenarios we provide an additional configuration property named `translatorFactory`.
+Set this to `DEFAULT` for directly loading our default implementation or to a fully-qualified classname for any other factory.
+Be aware that either our default implementation or your custom one needs to be on the classpath nevertheless.
+
 == Translating SQL to Cypher
 
 There's only one requirement to enable SQL to Cypher translation:

neo4j-jdbc-it/neo4j-jdbc-it-cp/src/test/java/org/neo4j/jdbc/it/cp/TranslationIT.java

@@ -18,7 +18,9 @@
  */
 package org.neo4j.jdbc.it.cp;
 
+import java.sql.DriverManager;
 import java.sql.SQLException;
+import java.util.Properties;
 
 import org.jooq.impl.ParserException;
 import org.junit.jupiter.api.Test;
@@ -29,6 +31,42 @@
 
 class TranslationIT extends IntegrationTestBase {
 
+	@Test
+	void shouldLoadTranslatorDirectly() throws SQLException {
+
+		var url = "jdbc:neo4j://%s:%d".formatted(this.neo4j.getHost(), this.neo4j.getMappedPort(7687));
+		var driver = DriverManager.getDriver(url);
+		var properties = new Properties();
+		properties.put("user", "neo4j");
+		properties.put("password", this.neo4j.getAdminPassword());
+		properties.put("translatorFactory", "default");
+		properties.put("enableSQLTranslation", "true");
+
+		try (var con = driver.connect(url, properties);
+				var stmt = con.createStatement();
+				var rs = stmt.executeQuery("SELECT 1")) {
+			assertThat(rs.next()).isTrue();
+			assertThat(rs.getInt(1)).isOne();
+		}
+
+	}
+
+	@Test
+	void shouldFailWhenLoadingInvalidClassDirectly() throws SQLException {
+
+		var url = "jdbc:neo4j://%s:%d".formatted(this.neo4j.getHost(), this.neo4j.getMappedPort(7687));
+		var driver = DriverManager.getDriver(url);
+		var properties = new Properties();
+		properties.put("user", "neo4j");
+		properties.put("password", this.neo4j.getAdminPassword());
+		properties.put("translatorFactory", "asd");
+		properties.put("enableSQLTranslation", "true");
+
+		assertThatExceptionOfType(SQLException.class).isThrownBy(() -> driver.connect(url, properties))
+			.withMessage("No translators available");
+
+	}
+
 	@Test
 	void shouldTranslateAsterisk() throws SQLException {
 

neo4j-jdbc-translator/impl/src/test/java/org/neo4j/jdbc/translator/impl/SqlToCypherTests.java

@@ -84,6 +84,11 @@ private static ResultSet makeColumns(String firstName, String... names) throws S
 		return personColumns;
 	}
 
+	@Test
+	void selectNShouldWork() {
+		assertThat(NON_PRETTY_PRINTING_TRANSLATOR.translate("SELECT 1")).isEqualTo("RETURN 1");
+	}
+
 	@Test
 	void parsingExceptionMustBeWrapped() {
 		assertThatIllegalArgumentException().isThrownBy(() -> NON_PRETTY_PRINTING_TRANSLATOR.translate("whatever"))

neo4j-jdbc/src/main/java/org/neo4j/jdbc/Neo4jDriver.java

@@ -19,6 +19,7 @@
 package org.neo4j.jdbc;
 
 import java.io.IOException;
+import java.lang.reflect.InvocationTargetException;
 import java.nio.file.Path;
 import java.security.GeneralSecurityException;
 import java.sql.Connection;
@@ -37,6 +38,7 @@
 import java.util.Properties;
 import java.util.ServiceLoader;
 import java.util.function.Supplier;
+import java.util.logging.Level;
 import java.util.logging.Logger;
 import java.util.regex.Pattern;
 
@@ -126,6 +128,14 @@ public final class Neo4jDriver implements Neo4jDriverExtensions {
 	 */
 	public static final String PROPERTY_SQL_TRANSLATION_CACHING_ENABLED = "cacheSQLTranslations";
 
+	/**
+	 * This is an alternative to the automatic configuration of translator factories and
+	 * can be applied to load a single translator. This is helpful in scenarios in which
+	 * an isolated class-loader is used, that prohibits access to the ServiceLoader
+	 * machinery.
+	 */
+	public static final String PROPERTY_TRANSLATOR_FACTORY = "translatorFactory";
+
 	private static final String PROPERTY_S2C_ALWAYS_ESCAPE_NAMES = "s2c.alwaysEscapeNames";
 
 	private static final String PROPERTY_S2C_PRETTY_PRINT_CYPHER = "s2c.prettyPrint";
@@ -278,10 +288,14 @@ public Connection connect(String url, Properties info) throws SQLException {
 		var enableTranslationCaching = driverConfig.enableTranslationCaching;
 		var rewriteBatchedStatements = driverConfig.rewriteBatchedStatements;
 		var rewritePlaceholders = driverConfig.rewritePlaceholders;
+		var translatorFactory = driverConfig.misc.get(PROPERTY_TRANSLATOR_FACTORY);
 
+		Supplier<List<TranslatorFactory>> translatorFactoriesSupplier = this::getSqlTranslatorFactories;
+		if (translatorFactory != null && !translatorFactory.isBlank()) {
+			translatorFactoriesSupplier = () -> getSqlTranslatorFactory(translatorFactory);
+		}
 		return new ConnectionImpl(boltConnection,
-				getSqlTranslatorSupplier(enableSqlTranslation, driverConfig.rawConfig(),
-						this::getSqlTranslatorFactories),
+				getSqlTranslatorSupplier(enableSqlTranslation, driverConfig.rawConfig(), translatorFactoriesSupplier),
 				enableSqlTranslation, enableTranslationCaching, rewriteBatchedStatements, rewritePlaceholders);
 	}
 
@@ -635,6 +649,24 @@ else if (ssl != null && sslMode == null && ssl) {
 		return new SSLProperties(sslMode, ssl);
 	}
 
+	private List<TranslatorFactory> getSqlTranslatorFactory(String translatorFactory) {
+
+		var fqn = "DEFAULT".equalsIgnoreCase(translatorFactory)
+				? "org.neo4j.jdbc.translator.impl.SqlToCypherTranslatorFactory" : translatorFactory;
+		try {
+			@SuppressWarnings("unchecked")
+			Class<TranslatorFactory> cls = (Class<TranslatorFactory>) Class.forName(fqn);
+			return List.of(cls.getDeclaredConstructor().newInstance());
+		}
+		catch (ClassNotFoundException ex) {
+			getParentLogger().log(Level.WARNING, "Translator factory {0} not found", new Object[] { fqn });
+		}
+		catch (NoSuchMethodException | InstantiationException | IllegalAccessException | InvocationTargetException ex) {
+			getParentLogger().log(Level.WARNING, ex, () -> "Could not load translator factory");
+		}
+		return List.of();
+	}
+
 	/**
 	 * Tries to load all available {@link TranslatorFactory SqlTranslator factories} via
 	 * the {@link ServiceLoader} machinery. Throws an exception if there is no

pom.xml

@@ -1070,6 +1070,7 @@
 				<pmd.skip>true</pmd.skip>
 				<skipTests>true</skipTests>
 				<sort.skip>true</sort.skip>
+				<spring-javaformat.skip>true</spring-javaformat.skip>
 			</properties>
 		</profile>
 	</profiles>