Implement Dao proxy generation with annotated sql statement execution

This functionality is inspired by JDBI but is not based on it's implementation.

3 files changed, 968 insertions, 4 deletions

diff --git a/src/main/java/com/iciql/Dao.java b/src/main/java/com/iciql/Dao.java
new file mode 100644
index 0000000..29b42f0
--- /dev/null
+++ b/src/main/java/com/iciql/Dao.java
@@ -0,0 +1,162 @@
+/*
+ * Copyright 2014 James Moger.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.iciql;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+import java.util.List;
+
+/**
+ * The Dao interface defines all CRUD methods for handling SQL object operations.
+ *
+ * @author James Moger
+ *
+ */
+public interface Dao extends AutoCloseable {
+
+	/**
+	 * Insert an object into the database.
+	 *
+	 * @param t
+	 * @return true if successful
+	 */
+	<T> boolean insert(T t);
+
+	/**
+	 * Insert an object into the database and return it's primary key.
+	 *
+	 * @param t
+	 * @return
+	 */
+	<T> long insertAndGetKey(T t);
+
+	/**
+	 * Insert all objects into the database.
+	 *
+	 * @param list
+	 */
+	<T> void insertAll(List<T> list);
+
+	/**
+	 * Insert all objects into the database and return the list of primary keys.
+	 *
+	 * @param t
+	 * @return a list of primary keys
+	 */
+	<T> List<Long> insertAllAndGetKeys(List<T> t);
+
+	/**
+	 * Updates an object in the database.
+	 *
+	 * @param t
+	 * @return true if successful
+	 */
+	<T> boolean update(T t);
+
+	/**
+	 * Updates all objects in the database.
+	 *
+	 * @param list
+	 */
+	<T> void updateAll(List<T> list);
+
+	/**
+	 * Inserts or updates an object in the database.
+	 *
+	 * @param t
+	 */
+	<T> void merge(T t);
+
+	/**
+	 * Deletes an object from the database.
+	 *
+	 * @param t
+	 * @return true if successful
+	 */
+	<T> boolean delete(T t);
+
+	/**
+	 * Deletes all objects from the database.
+	 *
+	 * @param list
+	 */
+	<T> void deleteAll(List<T> list);
+
+	/**
+	 * Returns the underlying Db instance for lower-level access to database methods
+	 * or direct JDBC access.
+	 *
+	 * @return the db instance
+	 */
+	Db db();
+
+	/**
+	 * Close the underlying Db instance.
+	 */
+	@Override
+	void close();
+
+	/**
+	 * Used to specify custom names for method parameters to be used
+	 * for the SqlQuery or SqlUpdate annotations.
+	 *
+	 * You don't need to explicitly bind the parameters as each parameter
+	 * is accessible by the standard "argN" syntax (0-indexed).
+	 *
+	 * Additionally, if you are compiling with Java 8 AND specifying the
+	 * -parameters flag for javac, then you may use the parameter's name.
+	 */
+	@Retention(RetentionPolicy.RUNTIME)
+	@Target({ ElementType.PARAMETER })
+	public @interface Bind {
+		String value();
+	}
+
+	/**
+	 *
+	 */
+	@Retention(RetentionPolicy.RUNTIME)
+	@Target({ ElementType.PARAMETER })
+	public @interface BindBean {
+		String value() default "";
+	}
+
+	/**
+	 * Used to indicate that a method should execute a query.
+	 */
+	@Retention(RetentionPolicy.RUNTIME)
+	@Target({ ElementType.METHOD })
+	public @interface SqlQuery {
+		String value();
+	}
+
+	/**
+	 * Used to indicate that a method should execute a statement.
+	 */
+	@Retention(RetentionPolicy.RUNTIME)
+	@Target({ ElementType.METHOD })
+	public @interface SqlStatement {
+		String value();
+	}
+
+	public class BeanBinder {
+		public void bind(BindBean bind, Object obj) {
+
+		}
+	}
+}
diff --git a/src/main/java/com/iciql/DaoProxy.java b/src/main/java/com/iciql/DaoProxy.java
new file mode 100644
index 0000000..db5f911
--- /dev/null
+++ b/src/main/java/com/iciql/DaoProxy.java
@@ -0,0 +1,792 @@
+/*
+ * Copyright 2014 James Moger.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.iciql;
+
+import java.lang.annotation.Annotation;
+import java.lang.reflect.Array;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.lang.reflect.Proxy;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import com.iciql.Iciql.DataTypeAdapter;
+import com.iciql.Iciql.TypeAdapter;
+import com.iciql.util.JdbcUtils;
+import com.iciql.util.StringUtils;
+import com.iciql.util.Utils;
+
+/**
+ * DaoProxy creates a dynamic instance of the provided Dao interface.
+ *
+ * @author James Moger
+ *
+ * @param <X>
+ */
+final class DaoProxy<X extends Dao> implements InvocationHandler, Dao {
+
+	private final Db db;
+
+	private final Class<X> daoInterface;
+
+	private final char bindingDelimiter = ':';
+
+	private final Map<Method, IndexedSql> indexedSqlCache;
+
+	DaoProxy(Db db, Class<X> daoInterface) {
+		this.db = db;
+		this.daoInterface = daoInterface;
+		this.indexedSqlCache = new ConcurrentHashMap<Method, IndexedSql>();
+	}
+
+	/**
+	 * Builds a proxy object for the DAO interface.
+	 *
+	 * @return a proxy object
+	 */
+	@SuppressWarnings("unchecked")
+	X buildProxy() {
+
+		if (!daoInterface.isInterface()) {
+			throw new IciqlException("Dao {0} must be an interface!", daoInterface.getName());
+		}
+
+		ClassLoader classLoader = db.getClass().getClassLoader();
+
+		Set<Class<?>> interfaces = new HashSet<Class<?>>();
+		interfaces.add(Dao.class);
+		interfaces.add(daoInterface);
+		for (Class<?> clazz : daoInterface.getInterfaces()) {
+			interfaces.add(clazz);
+		}
+
+		Class<?>[] constructorParams = { InvocationHandler.class };
+		Class<?>[] allInterfaces = interfaces.toArray(new Class<?>[interfaces.size()]);
+
+		try {
+
+			Class<?> proxyClass = Proxy.getProxyClass(classLoader, allInterfaces);
+			Constructor<?> proxyConstructor = proxyClass.getConstructor(constructorParams);
+			return (X) proxyConstructor.newInstance(new Object[] { this });
+
+		} catch (Exception e) {
+			throw new IciqlException(e);
+		}
+	}
+
+	/**
+	 * Invoke intercepts method calls and delegates execution to the appropriate object.
+	 */
+	@Override
+	public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+		try {
+
+			if (method.getDeclaringClass() == Dao.class) {
+
+				return method.invoke(this, args);
+
+			} else if (method.isAnnotationPresent(SqlQuery.class)) {
+
+				String sql = method.getAnnotation(SqlQuery.class).value();
+				return executeQuery(method, args, sql);
+
+			} else if (method.isAnnotationPresent(SqlStatement.class)) {
+
+				String sql = method.getAnnotation(SqlStatement.class).value();
+				return executeStatement(method, args, sql);
+
+			} else {
+
+				throw new IciqlException("Can not invoke non-dao method {0}.{1}",
+						method.getDeclaringClass().getSimpleName(), method.getName());
+
+			}
+
+		} catch (InvocationTargetException te) {
+			throw te.getCause();
+		}
+	}
+
+	/**
+	 * Execute a query.
+	 *
+	 * @param method
+	 * @param methodArgs
+	 * @param sql
+	 * @return the result
+	 */
+	private Object executeQuery(Method method, Object[] methodArgs, String sql) {
+
+		/*
+		 * Determine and validate the return type
+		 */
+		Class<?> returnType = method.getReturnType();
+
+		if (void.class == returnType) {
+			throw new IciqlException("You must specify a return type for @{0} {1}.{2}!",
+					SqlQuery.class.getSimpleName(), method.getDeclaringClass().getSimpleName(), method.getName());
+		}
+
+		if (Collection.class.isAssignableFrom(returnType)) {
+			throw new IciqlException("You may not return a collection for an @{0} method, please change the return type of {1}.{2} to YourClass[]!",
+					SqlQuery.class.getSimpleName(), method.getDeclaringClass().getSimpleName(), method.getName());
+		}
+
+		boolean isArray = false;
+		if (returnType.isArray()) {
+			isArray = true;
+			returnType = returnType.getComponentType();
+		}
+
+		boolean isJavaType = returnType.isEnum()
+				|| returnType.isPrimitive()
+				|| java.lang.Boolean.class.isAssignableFrom(returnType)
+				|| java.lang.Number.class.isAssignableFrom(returnType)
+				|| java.lang.String.class.isAssignableFrom(returnType)
+				|| java.util.Date.class.isAssignableFrom(returnType)
+				|| byte[].class.isAssignableFrom(returnType);
+
+		// determine the return type adapter, if any
+		DataTypeAdapter<?> adapter = null;
+		for (Annotation annotation : method.getAnnotations()) {
+			if (annotation.annotationType() == TypeAdapter.class) {
+				TypeAdapter typeAdapter = (TypeAdapter) annotation;
+				adapter = db.getDialect().getAdapter(typeAdapter.value());
+				break;
+			} else if (annotation.annotationType().isAnnotationPresent(TypeAdapter.class)) {
+				TypeAdapter typeAdapter = annotation.annotationType().getAnnotation(TypeAdapter.class);
+				adapter = db.getDialect().getAdapter(typeAdapter.value());
+				break;
+			}
+		}
+
+		/*
+		 * Prepare & execute sql
+		 */
+		PreparedSql preparedSql = prepareSql(method, methodArgs, sql);
+
+		List<Object> objects;
+		if (!isJavaType && adapter == null) {
+
+			// query of an Iciql model
+			objects = db.executeQuery(returnType, preparedSql.sql, preparedSql.parameters);
+
+		} else {
+
+			// query of (array of) standard Java type or a DataTypeAdapter type
+			objects = Utils.newArrayList();
+			ResultSet rs = db.executeQuery(preparedSql.sql, preparedSql.parameters);
+			try {
+
+				while (rs.next()) {
+
+					Object o = rs.getObject(1);
+					Object value;
+
+					if (adapter == null) {
+						// use internal Iciql type conversion
+						value = Utils.convert(o, returnType);
+					} else {
+						// use the type adapter to convert the JDBC object to a domain type
+						value = adapter.deserialize(o);
+					}
+
+					objects.add(value);
+
+				}
+
+			} catch (SQLException e) {
+				throw new IciqlException(e);
+			} finally {
+				JdbcUtils.closeSilently(rs);
+			}
+
+		}
+
+		/*
+		 * Return the results
+		 */
+		if (objects == null || objects.isEmpty()) {
+
+			// no results
+			if (isArray) {
+				// return an empty array
+				return Array.newInstance(returnType, 0);
+			}
+
+			// nothing to return!
+			return null;
+
+		} else if (isArray) {
+
+			// return an array of object results
+			Object array = Array.newInstance(returnType, objects.size());
+			for (int i = 0; i < objects.size(); i++) {
+				Array.set(array, i, objects.get(i));
+			}
+			return array;
+
+		}
+
+		// return first element
+		return objects.get(0);
+	}
+
+
+	/**
+	 * Execute a statement.
+	 *
+	 * @param method
+	 * @param methodArgs
+	 * @param sql
+	 * @return the result
+	 */
+	private Object executeStatement(Method method, Object[] methodArgs, String sql) {
+
+		/*
+		 * Determine and validate the return type
+		 */
+		Class<?> returnType = method.getReturnType();
+
+		if (void.class != returnType && boolean.class != returnType && int.class != returnType) {
+
+			throw new IciqlException("Invalid return type '{0}' for @{1} {2}.{3}!",
+					returnType.getSimpleName(), SqlQuery.class.getSimpleName(),
+					method.getDeclaringClass().getSimpleName(), method.getName());
+		}
+
+		/*
+		 * Prepare & execute sql
+		 */
+		PreparedSql preparedSql = prepareSql(method, methodArgs, sql);
+		int rows = db.executeUpdate(preparedSql.sql, preparedSql.parameters);
+
+		/*
+		 * Return the results
+		 */
+		if (void.class == returnType) {
+
+			// return nothing
+			return null;
+
+		} else if (boolean.class == returnType) {
+
+			// return true if any rows were affected
+			return rows > 0;
+
+		} else {
+
+			// return number of rows
+			return rows;
+
+		}
+	}
+
+	/**
+	 * Prepares an sql statement and execution parameters based on the supplied
+	 * method and it's arguments.
+	 *
+	 * @param method
+	 * @param methodArgs
+	 * @param sql
+	 * @return a prepared sql statement and arguments
+	 */
+	private PreparedSql prepareSql(Method method, Object[] methodArgs, String sql) {
+
+		if (methodArgs == null || methodArgs.length == 0) {
+			// no method arguments
+			return new PreparedSql(sql, null);
+		}
+
+		IndexedSql indexedSql = indexedSqlCache.get(method);
+
+		if (indexedSql == null) {
+
+			// index the sql and method args
+			indexedSql = indexSql(method, sql);
+
+			// cache the indexed sql for re-use
+			indexedSqlCache.put(method, indexedSql);
+		}
+
+		final PreparedSql preparedSql = indexedSql.prepareSql(db, methodArgs);
+		return preparedSql;
+	}
+
+	/**
+	 * Indexes an sql statement and method args based on the supplied
+	 * method and it's arguments.
+	 *
+	 * @param method
+	 * @param sql
+	 * @return an indexed sql statement and arguments
+	 */
+	private IndexedSql indexSql(Method method, String sql) {
+
+		Map<String, IndexedArgument> parameterIndex = buildParameterIndex(method);
+
+		// build a regex to extract parameter names from the sql statement
+		StringBuilder sb = new StringBuilder();
+		sb.append(bindingDelimiter);
+		sb.append("{1}(\\?");
+		for (String name : parameterIndex.keySet()) {
+			sb.append("|");
+			// strip binding delimeter from name
+			sb.append(name);
+		}
+		sb.append(')');
+
+		// identify parameters, replace with the '?' PreparedStatement
+		// delimiter and build the PreparedStatement parameters array
+		final String regex = sb.toString();
+		final Pattern p = Pattern.compile(regex);
+		final Matcher m = p.matcher(sql);
+		final StringBuffer buffer = new StringBuffer();
+
+		List<IndexedArgument> indexedArgs = Utils.newArrayList();
+		int count = 0;
+		while (m.find()) {
+			String binding = m.group(1);
+			m.appendReplacement(buffer, "?");
+
+			IndexedArgument indexedArg;
+			if ("?".equals(binding)) {
+				// standard ? JDBC placeholder
+				indexedArg = parameterIndex.get("arg" + count);
+			} else {
+				// named placeholder
+				indexedArg = parameterIndex.get(binding);
+			}
+
+			if (indexedArg == null) {
+				throw new IciqlException("Unbound SQL parameter '{0}' in {1}.{2}",
+						binding, method.getDeclaringClass().getSimpleName(), method.getName());
+			}
+			indexedArgs.add(indexedArg);
+
+			count++;
+		}
+		m.appendTail(buffer);
+
+		final String statement = buffer.toString();
+
+		// create an IndexedSql container for the statement and indexes
+		return new IndexedSql(statement, Collections.unmodifiableList(indexedArgs));
+
+	}
+
+	/**
+	 * Builds an index of parameter name->(position,typeAdapter) from the method arguments
+	 * array. This index is calculated once per method.
+	 *
+	 * @param method
+	 * @return a bindings map of ("name", IndexedArgument) pairs
+	 */
+	private Map<String, IndexedArgument> buildParameterIndex(Method method) {
+
+		Map<String, IndexedArgument> index = new TreeMap<String, IndexedArgument>();
+
+		Annotation [][] annotationsMatrix = method.getParameterAnnotations();
+		for (int i = 0; i < annotationsMatrix.length; i++) {
+
+			Annotation [] annotations = annotationsMatrix[i];
+
+			/*
+			 * Conditionally map the bean properties of the method argument
+			 * class to Method and Field instances.
+			 */
+			BindBean bean = getAnnotation(BindBean.class, annotations);
+			if (bean != null) {
+				final String prefix = bean.value();
+				final Class<?> argumentClass = method.getParameterTypes()[i];
+				Map<String, IndexedArgument> beanIndex = buildBeanIndex(i, prefix, argumentClass);
+				index.putAll(beanIndex);
+			}
+
+			Class<? extends DataTypeAdapter<?>> typeAdapter = Utils.getDataTypeAdapter(annotations);
+			final IndexedArgument indexedArgument = new IndexedArgument(i, typeAdapter);
+
+			// :N - 1-indexed, like JDBC ResultSet
+			index.put("" + (i + 1), indexedArgument);
+
+			// argN - 0-indexed, like Reflection
+			index.put("arg" + i, indexedArgument);
+
+			// Bound name
+			Bind binding = getAnnotation(Bind.class, annotations);
+			if (binding!= null && !binding.value().isEmpty()) {
+				index.put(binding.value(), indexedArgument);
+			}
+
+			// try mapping Java 8 argument names, may overwrite argN
+			try {
+				Class<?> nullArgs = null;
+				Method getParameters = method.getClass().getMethod("getParameters", nullArgs);
+				if (getParameters != null) {
+					Object [] parameters = (Object []) getParameters.invoke(method, nullArgs);
+					if (parameters != null) {
+						Object o = parameters[i];
+						Method getName = o.getClass().getMethod("getName", nullArgs);
+						String j8name = getName.invoke(o, nullArgs).toString();
+						if (!j8name.isEmpty()) {
+							index.put(j8name, indexedArgument);
+						}
+					}
+				}
+			} catch (Throwable t) {
+			}
+		}
+
+		return index;
+	}
+
+	/**
+	 * Builds an index of parameter name->(position,method) from the method arguments
+	 * array. This index is calculated once per method.
+	 *
+	 * @param argumentIndex
+	 * @param prefix
+	 * @param beanClass
+	 * @return a bindings map of ("prefix.property", IndexedArgument) pairs
+	 */
+	private Map<String, IndexedArgument> buildBeanIndex(int argumentIndex, String prefix, Class<?> beanClass) {
+
+		final String beanPrefix = StringUtils.isNullOrEmpty(prefix) ? "" : (prefix + ".");
+		final Map<String, IndexedArgument> index = new TreeMap<String, IndexedArgument>();
+
+		// map JavaBean property getters
+		for (Method method : beanClass.getMethods()) {
+
+			if (Modifier.isStatic(method.getModifiers())
+				|| method.getReturnType() == void.class
+				|| method.getParameterTypes().length > 0
+				|| method.getDeclaringClass() == Object.class) {
+
+				// not a JavaBean property
+				continue;
+			}
+
+			final String propertyName;
+			final String name = method.getName();
+			if (name.startsWith("get")) {
+				propertyName = method.getName().substring(3);
+			} else if (name.startsWith("is")) {
+				propertyName = method.getName().substring(2);
+			} else {
+				propertyName = null;
+			}
+
+			if (propertyName == null) {
+				// not a conventional JavaBean property
+				continue;
+			}
+
+			final String binding = beanPrefix + preparePropertyName(propertyName);
+			final IndexedArgument indexedArg = new IndexedArgument(argumentIndex, method);
+
+			index.put(binding, indexedArg);
+		}
+
+		// map public instance fields
+		for (Field field : beanClass.getFields()) {
+
+			if (Modifier.isStatic(field.getModifiers())) {
+				// not a JavaBean property
+				continue;
+			}
+
+			final String binding = beanPrefix + preparePropertyName(field.getName());
+			final IndexedArgument indexedArg = new IndexedArgument(argumentIndex, field);
+
+			index.put(binding, indexedArg);
+
+		}
+
+		return index;
+	}
+
+	@SuppressWarnings("unchecked")
+	private <T> T getAnnotation(Class<T> annotationClass, Annotation [] annotations) {
+		if (annotations != null) {
+			for (Annotation annotation : annotations) {
+				if (annotation.annotationType() == annotationClass) {
+					return (T) annotation;
+				}
+			}
+		}
+		return null;
+	}
+
+	private String preparePropertyName(String value) {
+		return Character.toLowerCase(value.charAt(0)) + value.substring(1);
+	}
+
+	/*
+	 *
+	 * Standard Dao method implementations delegate to the underlying Db
+	 *
+	 */
+
+	@Override
+	public final Db db() {
+		return db;
+	}
+
+	@Override
+	public final <T> boolean insert(T t) {
+		return db.insert(t);
+	}
+
+	@Override
+	public final <T> void insertAll(List<T> t) {
+		db.insertAll(t);
+	}
+
+	@Override
+	public final <T> long insertAndGetKey(T t) {
+		return db.insertAndGetKey(t);
+	}
+
+	@Override
+	public final <T> List<Long> insertAllAndGetKeys(List<T> t) {
+		return db.insertAllAndGetKeys(t);
+	}
+
+	@Override
+	public final <T> boolean update(T t) {
+		return db.update(t);
+	}
+
+	@Override
+	public final <T> void updateAll(List<T> t) {
+		db.updateAll(t);
+	}
+
+	@Override
+	public final <T> void merge(T t) {
+		db.merge(t);
+	}
+
+	@Override
+	public final <T> boolean delete(T t) {
+		return db.delete(t);
+	}
+
+	@Override
+	public final <T> void deleteAll(List<T> t) {
+		db.deleteAll(t);
+	}
+
+	@Override
+	public final void close() {
+		db.close();
+	}
+
+	/**
+	 * Container class to hold the prepared JDBC SQL statement and execution
+	 * parameters.
+	 */
+	private class PreparedSql {
+		final String sql;
+		final Object [] parameters;
+
+		PreparedSql(String sql, Object [] parameters) {
+			this.sql = sql;
+			this.parameters = parameters;
+		}
+
+		@Override
+		public String toString() {
+			return sql;
+		}
+
+	}
+
+	/**
+	 * Container class to hold a parsed JDBC SQL statement and
+	 * IndexedParameters.
+	 * <p>
+	 * Instances of this class are cached because they are functional processing
+	 * containers as they contain Method and Field references for binding beans
+	 * and matching to method arguments.
+	 * </p>
+	 */
+	private class IndexedSql {
+		final String sql;
+		final List<IndexedArgument> indexedArgs;
+
+		IndexedSql(String sql, List<IndexedArgument> indexedArgs) {
+			this.sql = sql;
+			this.indexedArgs = indexedArgs;
+		}
+
+		/**
+		 * Prepares the method arguments for statement execution.
+		 *
+		 * @param db
+		 * @param methodArgs
+		 * @return the prepared sql statement and parameters
+		 */
+		PreparedSql prepareSql(Db db, Object [] methodArgs) {
+
+			Object [] parameters = new Object[indexedArgs.size()];
+
+			for (int i = 0; i < indexedArgs.size(); i++) {
+
+				IndexedArgument indexedArg = indexedArgs.get(i);
+				Object methodArg = methodArgs[indexedArg.index];
+
+				Object value = methodArg;
+				Class<? extends DataTypeAdapter<?>> typeAdapter = indexedArg.typeAdapter;
+
+				if (indexedArg.method != null) {
+
+					// execute the bean method
+					try {
+
+						value = indexedArg.method.invoke(methodArg);
+						typeAdapter = Utils.getDataTypeAdapter(indexedArg.method.getAnnotations());
+
+					} catch (Exception e) {
+						throw new IciqlException(e);
+					}
+
+				} else if (indexedArg.field != null) {
+
+					// extract the field value
+					try {
+
+						value = indexedArg.field.get(methodArg);
+						typeAdapter = Utils.getDataTypeAdapter(indexedArg.field.getAnnotations());
+
+					} catch (Exception e) {
+						throw new IciqlException(e);
+					}
+
+				} else if (typeAdapter == null) {
+
+					// identify the type adapter for the argument class
+					typeAdapter = Utils.getDataTypeAdapter(methodArg.getClass().getAnnotations());
+				}
+
+				// prepare the parameter
+				parameters[i] = prepareParameter(db, value, typeAdapter);
+
+			}
+
+			return new PreparedSql(sql, parameters);
+
+		}
+
+		/**
+		 * Prepares a method argument to an sql parameter for transmission to a
+		 * database.
+		 *
+		 * @param db
+		 * @param arg
+		 * @param typeAdapter
+		 * @return a prepared parameter
+		 */
+		private Object prepareParameter(Db db, Object arg, Class<? extends DataTypeAdapter<?>> typeAdapter) {
+
+			if (typeAdapter != null) {
+
+				// use a type adapter to serialize the method argument
+				Object o = db.getDialect().serialize(arg, typeAdapter);
+				return o;
+
+			} else {
+
+				// use the method argument
+				return arg;
+
+			}
+
+		}
+
+		@Override
+		public String toString() {
+			return sql;
+		}
+	}
+
+	/**
+	 * IndexedArgument holds cached information about how to process an method
+	 * argument by it's index in the method arguments array.
+	 * <p>
+	 * An argument may be passed-through, might be bound to a bean property,
+	 * might be transformed with a type adapter, or a combination of these.
+	 * </p>
+	 */
+	private class IndexedArgument {
+		final int index;
+		final Class<? extends DataTypeAdapter<?>> typeAdapter;
+		final Method method;
+		final Field field;
+
+		IndexedArgument(int index, Class<? extends DataTypeAdapter<?>> typeAdapter) {
+			this.index = index;
+			this.typeAdapter = typeAdapter;
+			this.method = null;
+			this.field = null;
+		}
+
+		IndexedArgument(int methodArgIndex, Method method) {
+			this.index = methodArgIndex;
+			this.typeAdapter = null;
+			this.method = method;
+			this.field = null;
+		}
+
+		IndexedArgument(int methodArgIndex, Field field) {
+			this.index = methodArgIndex;
+			this.typeAdapter = null;
+			this.method = null;
+			this.field = field;
+		}
+
+		@Override
+		public String toString() {
+
+			String accessor;
+			if (method != null) {
+				accessor = "M:" + method.getDeclaringClass().getSimpleName() + "." + method.getName();
+			} else if (field != null) {
+				accessor = "F:" + field.getDeclaringClass().getSimpleName() + "." + field.getName();
+			} else {
+				accessor = "A:arg";
+			}
+
+			return index + ":" + accessor + (typeAdapter == null ? "" : (":" + typeAdapter.getSimpleName()));
+		}
+
+	}
+
+}
diff --git a/src/main/java/com/iciql/Db.java b/src/main/java/com/iciql/Db.java
index ca43e63..13c9260 100644
--- a/src/main/java/com/iciql/Db.java
+++ b/src/main/java/com/iciql/Db.java
@@ -194,7 +194,17 @@ public class Db implements AutoCloseable {
 		return new Db(conn);
 	}
 
-
+	/**
+	 * Returns a new DAO instance for the specified class.
+	 *
+	 * @param daoClass
+	 * @return
+	 * @throws Exception
+	 */
+	@SuppressWarnings("resource")
+	public <X extends Dao> X open(Class<X> daoClass) {
+		return new DaoProxy<X>(this, daoClass).buildProxy();
+	}
 
 	/**
 	 * Convenience function to avoid import statements in application code.
@@ -675,7 +685,7 @@ public class Db implements AutoCloseable {
 	 */
 	public ResultSet executeQuery(String sql, Object... args) {
 		try {
-			if (args.length == 0) {
+			if (args == null || args.length == 0) {
 				return conn.createStatement().executeQuery(sql);
 			} else {
 				PreparedStatement stat = conn.prepareStatement(sql);
@@ -717,7 +727,7 @@ public class Db implements AutoCloseable {
 	public <T> List<T> executeQuery(Class<? extends T> modelClass, String sql, Object... args) {
 		ResultSet rs = null;
 		try {
-			if (args.length == 0) {
+			if (args == null || args.length == 0) {
 				rs = conn.createStatement().executeQuery(sql);
 			} else {
 				PreparedStatement stat = conn.prepareStatement(sql);
@@ -748,7 +758,7 @@ public class Db implements AutoCloseable {
 		Statement stat = null;
 		try {
 			int updateCount;
-			if (args.length == 0) {
+			if (args == null || args.length == 0) {
 				stat = conn.createStatement();
 				updateCount = stat.executeUpdate(sql);
 			} else {