SOLR-7915: Provide pluggable context tool support for VelocityResponseWriter

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1700691 13f79535-47bb-0310-9956-ffa450edef68

solr/CHANGES.txt

@@ -144,6 +144,8 @@ New Features
 
 * SOLR-4316: Add a collections dropdown to angular admin UI (Upayavira, Shalin Shekhar Mangar)
 
+* SOLR-7915: Provide pluggable context tool support for VelocityResponseWriter (Erik Hatcher)
+
 Bug Fixes
 ----------------------
 

solr/contrib/velocity/src/java/org/apache/solr/response/VelocityResponseWriter.java

@@ -25,7 +25,9 @@ import java.io.StringWriter;
 import java.io.Writer;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.Locale;
+import java.util.Map;
 import java.util.Properties;
 import java.util.ResourceBundle;
 
@@ -45,7 +47,6 @@ import org.apache.velocity.runtime.RuntimeConstants;
 import org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader;
 import org.apache.velocity.tools.ConversionUtils;
 import org.apache.velocity.tools.generic.ComparisonDateTool;
-import org.apache.velocity.tools.generic.ContextTool;
 import org.apache.velocity.tools.generic.DisplayTool;
 import org.apache.velocity.tools.generic.EscapeTool;
 import org.apache.velocity.tools.generic.ListTool;
@@ -84,6 +85,7 @@ public class VelocityResponseWriter implements QueryResponseWriter, SolrCoreAwar
   private static final Logger log = LoggerFactory.getLogger(VelocityResponseWriter.class);
   private static final SolrVelocityLogger velocityLogger = new SolrVelocityLogger(log);
   private Properties velocityInitProps = new Properties();
+  private Map<String,String> customTools = new HashMap<String,String>();
 
   @Override
   public void init(NamedList args) {
@@ -112,6 +114,14 @@ public class VelocityResponseWriter implements QueryResponseWriter, SolrCoreAwar
     solrResourceLoaderEnabled = (null == srle ? true : srle);
 
     initPropertiesFileName = (String) args.get(PROPERTIES_FILE);
+
+    NamedList tools = (NamedList)args.get("tools");
+    if (tools != null) {
+      for(Object t : tools) {
+        Map.Entry tool = (Map.Entry)t;
+        customTools.put(tool.getKey().toString(), tool.getValue().toString());
+      }
+    }
   }
 
   @Override
@@ -183,10 +193,8 @@ public class VelocityResponseWriter implements QueryResponseWriter, SolrCoreAwar
   private VelocityContext createContext(SolrQueryRequest request, SolrQueryResponse response) {
     VelocityContext context = new VelocityContext();
 
-    context.put("request", request);
-
     // Register useful Velocity "tools"
-    context.put("log", log);   // TODO: add test
+    context.put("log", log);   // TODO: add test; TODO: should this be overridable with a custom "log" named tool?
     context.put("esc", new EscapeTool());
     context.put("date", new ComparisonDateTool());
     context.put("list", new ListTool());
@@ -198,6 +206,25 @@ public class VelocityResponseWriter implements QueryResponseWriter, SolrCoreAwar
         request.getCore().getSolrConfig().getResourceLoader().getClassLoader(),
         request.getParams().get(LOCALE)));
 
+/*
+    // Custom tools, specified in config as:
+        <queryResponseWriter name="velocityWithCustomTools" class="solr.VelocityResponseWriter">
+          <lst name="tools">
+            <str name="mytool">com.example.solr.velocity.MyTool</str>
+          </lst>
+        </queryResponseWriter>
+
+
+*/
+    // Custom tools can override any of the built-in tools provided above, by registering one with the same name
+    for(String name : customTools.keySet()) {
+      context.put(name, SolrCore.createInstance(customTools.get(name), Object.class, "VrW custom tool", request.getCore(), request.getCore().getResourceLoader()));
+    }
+
+    // custom tools _cannot_ override context objects added below, like $request and $response
+    // TODO: at least log a warning when one of the *fixed* tools classes in name with a custom one, currently silently ignored
+
+
     // Turn the SolrQueryResponse into a SolrResponse.
     // QueryResponse has lots of conveniences suitable for a view
     // Problem is, which SolrResponse class to use?
@@ -221,6 +248,8 @@ public class VelocityResponseWriter implements QueryResponseWriter, SolrCoreAwar
       rsp = new SolrResponseBase();
       rsp.setResponse(parsedResponse);
     }
+
+    context.put("request", request);
     context.put("response", rsp);
 
     return context;

solr/contrib/velocity/src/test-files/velocity/solr/collection1/conf/solrconfig.xml

@@ -35,4 +35,20 @@
   <queryResponseWriter name="velocityWithInitProps" class="solr.VelocityResponseWriter">
     <str name="init.properties.file">velocity-init.properties</str>
   </queryResponseWriter>
+
+  <queryResponseWriter name="velocityWithCustomTools" class="solr.VelocityResponseWriter">
+    <!-- Enable params resource loader to make tests leaner, no external template needed -->
+    <bool name="params.resource.loader.enabled">true</bool>
+
+    <lst name="tools">
+      <!-- how someone would typically add a custom tool, with a custom, non-clashing name -->
+      <str name="mytool">org.apache.solr.velocity.MockTool</str>
+
+      <!-- override the $log context object -->
+      <str name="log">org.apache.solr.velocity.MockTool</str>
+
+      <!-- Try to override response, but ignored -->
+      <str name="response">org.apache.solr.velocity.MockTool</str>
+    </lst>
+  </queryResponseWriter>
 </config>

solr/contrib/velocity/src/test-files/velocity/solr/collection1/conf/velocity/custom_tool.vm

@@ -0,0 +1 @@
+$!mytool.star("foo")

solr/contrib/velocity/src/test/org/apache/solr/velocity/MockTool.java

@@ -0,0 +1,34 @@
+package org.apache.solr.velocity;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.
+ */
+
+import org.apache.solr.core.SolrCore;
+
+public class MockTool {
+  private final SolrCore core;
+
+  public MockTool(SolrCore core) {
+    this.core = core;
+  }
+
+  public String star(String str) {
+    return "** " + str + " **";
+  }
+
+  public SolrCore getCore() { return core; }
+}

solr/contrib/velocity/src/test/org/apache/solr/velocity/VelocityResponseWriterTest.java

@@ -119,6 +119,29 @@ public class VelocityResponseWriterTest extends SolrTestCaseJ4 {
     assertEquals("", h.query(req("q","*:*", "wt","velocityWithInitProps",VelocityResponseWriter.TEMPLATE,"foreach")));
   }
 
+  @Test
+  public void testCustomTools() throws Exception {
+    assertEquals("", h.query(req("q","*:*", "wt","velocity",VelocityResponseWriter.TEMPLATE,"custom_tool")));
+    assertEquals("** LATERALUS **", h.query(req("q","*:*", "wt","velocityWithCustomTools",VelocityResponseWriter.TEMPLATE,"t",
+            SolrParamResourceLoader.TEMPLATE_PARAM_PREFIX+"t", "$mytool.star(\"LATERALUS\")")));
+
+    // Does $log get overridden?
+    assertEquals("** log overridden **", h.query(req("q","*:*", "wt","velocityWithCustomTools",VelocityResponseWriter.TEMPLATE,"t",
+            SolrParamResourceLoader.TEMPLATE_PARAM_PREFIX+"t", "$log.star(\"log overridden\")")));
+
+    // Does $response get overridden?  actual blank response because of the bang on $! reference that silences bogus $-references
+    assertEquals("", h.query(req("q","*:*", "wt","velocityWithCustomTools",VelocityResponseWriter.TEMPLATE,"t",
+        SolrParamResourceLoader.TEMPLATE_PARAM_PREFIX+"t", "$!response.star(\"response overridden??\")")));
+
+    // Custom tools can also have a SolrCore-arg constructor because they are instantiated with SolrCore.createInstance
+    // TODO: do we really need to support this?  no great loss, as a custom tool could take a SolrCore object as a parameter to
+    // TODO: any method, so one could do $mytool.my_method($request.core)
+    // I'm currently inclined to make this feature undocumented/unsupported, as we may want to instantiate classes
+    // in a different manner that only supports no-arg constructors, commented (passing) test case out
+//    assertEquals("collection1", h.query(req("q","*:*", "wt","velocityWithCustomTools",VelocityResponseWriter.TEMPLATE,"t",
+//        SolrParamResourceLoader.TEMPLATE_PARAM_PREFIX+"t", "$mytool.core.name")));
+  }
+
   @Test
   public void testLocaleFeature() throws Exception {
     assertEquals("Color", h.query(req("q", "*:*", "wt", "velocity", VelocityResponseWriter.TEMPLATE, "locale",