Code Fix for issue #1 (Add support for adding attributes to the Velocity context)

src/main/java/org/mybatis/scripting/velocity/VelocityFacade.java

@@ -17,8 +17,11 @@
 
 import java.io.StringReader;
 import java.io.StringWriter;
+import java.util.Collections;
+import java.util.HashMap;
 import java.util.Map;
 import java.util.Properties;
+
 import org.apache.ibatis.builder.BuilderException;
 import org.apache.velocity.Template;
 import org.apache.velocity.VelocityContext;
@@ -27,15 +30,18 @@
 
 public class VelocityFacade {
 
+  private static final String ADDITIONAL_CTX_ATTRIBUTES_KEY = "additional.context.attributes";
+  private static final String EXTERNAL_PROPERTIES = "mybatis-velocity.properties";
+
   private static final RuntimeInstance engine;
+
+  /** Contains thread safe objects to be set in the velocity context.*/
+  private static final Map<String, Object> additionalCtxAttributes;
+  private static final Properties settings;
 
   static {
-    final Properties settings = new Properties();
-    settings.setProperty("userdirective",
-        TrimDirective.class.getName()  + "," +
-        WhereDirective.class.getName() + "," +
-        SetDirective.class.getName()   + "," +
-        RepeatDirective.class.getName());
+    settings = loadPropeties();
+    additionalCtxAttributes = Collections.unmodifiableMap(loadAdditionalCtxAttributes());
     engine = new RuntimeInstance();
     engine.init(settings);
   }
@@ -56,8 +62,50 @@ public static Object compile(String script, String name) {
 
   public static String apply(Object template, Map<String, Object> context) {
     final StringWriter out = new StringWriter();
-    ((Template)template).merge(new VelocityContext(context), out);
+    context.putAll(additionalCtxAttributes);
+    ((Template) template).merge(new VelocityContext(context), out);
     return out.toString();
   }
 
+  private static Properties loadPropeties() {
+    final Properties props = new Properties();
+    // Defaults
+    props.setProperty("resource.loader", "class");
+    props.setProperty("class.resource.loader.class", "org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader");
+
+
+    try {
+      // External properties
+      ClassLoader cl = Thread.currentThread().getContextClassLoader();
+      props.load(cl.getResourceAsStream(EXTERNAL_PROPERTIES));
+    } catch (Exception ex) {
+      // No custom properties
+    }
+
+    props.setProperty("userdirective",
+            TrimDirective.class.getName() + ","
+            + WhereDirective.class.getName() + ","
+            + SetDirective.class.getName() + ","
+            + RepeatDirective.class.getName());
+    return props;
+  }
+
+  private static Map<String, Object> loadAdditionalCtxAttributes() {
+    Map<String, Object> attributes = new HashMap<String, Object>();
+    String additionalContextAttributes = settings.getProperty(ADDITIONAL_CTX_ATTRIBUTES_KEY);
+    if (additionalContextAttributes == null) {
+      return attributes;
+    }
+
+    try {
+      String[] entries = additionalContextAttributes.split(",");
+      for (String str : entries) {
+        String[] entry = str.trim().split(":");
+        attributes.put(entry[0].trim(), Class.forName(entry[1].trim()).newInstance());
+      }
+    } catch (Exception ex) {
+       throw new BuilderException("Error parsing velocity property '" + ADDITIONAL_CTX_ATTRIBUTES_KEY + "'", ex);
+    }
+    return attributes;
+  }
 }

src/test/java/mybatis-velocity.properties

@@ -0,0 +1 @@
+additional.context.attributes=trailingWildCardFormatter:org.mybatis.scripting.velocity.use.TrailingWildCardFormatter

src/test/java/org/mybatis/scripting/velocity/use/TrailingWildCardFormatter.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2012 MyBatis.org.
+ *
+ * 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 org.mybatis.scripting.velocity.use;
+
+public class TrailingWildCardFormatter {
+
+  public String formatLiteral(Object val) {
+    if (val == null) {
+      return "''";
+    }
+    String param = val.toString().replaceAll("\'", "\''");
+    return "'" + param + "%'";
+  }
+
+  public String format(Object val) {
+    if (val == null) {
+      return "";
+    }
+    return val + "%";
+  }
+
+}

src/test/java/org/mybatis/scripting/velocity/use/VelocityLanguageTest.java

@@ -129,6 +129,40 @@ public void testDynamicSelectWithExpressionParams() {
     }
   }
 
+  @Test
+  public void testSelectNamesWithFormattedParam() {
+    SqlSession sqlSession = sqlSessionFactory.openSession();
+    try {
+
+      Parameter p = new Parameter(true, "Fli");
+      List<Name> answer = sqlSession.selectList("org.mybatis.scripting.velocity.use.selectNamesWithFormattedParam", p);
+      assertEquals(3, answer.size());
+      for (Name n : answer) {
+        assertEquals("Flintstone", n.getLastName());
+      }
+
+    } finally {
+      sqlSession.close();
+    }
+  }
+
+  @Test
+  public void testSelectNamesWithFormattedParamSafe() {
+    SqlSession sqlSession = sqlSessionFactory.openSession();
+    try {
+
+      Parameter p = new Parameter(true, "Fli");
+      List<Name> answer = sqlSession.selectList("org.mybatis.scripting.velocity.use.selectNamesWithFormattedParamSafe", p);
+      assertEquals(3, answer.size());
+      for (Name n : answer) {
+        assertEquals("Flintstone", n.getLastName());
+      }
+
+    } finally {
+      sqlSession.close();
+    }
+  }
+
   @Test
   @SuppressWarnings("unchecked")
   public void testDynamicSelectWithIteration() {

src/test/java/org/mybatis/scripting/velocity/use/mapper.xml

@@ -42,6 +42,19 @@
     WHERE lastName LIKE @{pattern, javaType=string}
   </select>
 
+  <select id="selectNamesWithFormattedParam" resultType="org.mybatis.scripting.velocity.use.Name">
+    SELECT <include refid="columns" />
+    FROM names
+    WHERE lastName LIKE $trailingWildCardFormatter.formatLiteral($_parameter.name)
+  </select>
+
+  <select id="selectNamesWithFormattedParamSafe" resultType="org.mybatis.scripting.velocity.use.Name">
+    #set( $pattern = $trailingWildCardFormatter.format($_parameter.name) )
+    SELECT <include refid="columns" />
+    FROM names
+    WHERE lastName LIKE @{pattern, javaType=string}
+  </select>
+
   <select id="selectNamesWithIteration" resultType="org.mybatis.scripting.velocity.use.Name">
     SELECT *
     FROM names