| |
| /* |
| * 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. |
| */ |
| |
| package org.apache.sling.scripting.handlebars; |
| |
| import java.io.IOException; |
| import java.io.PrintWriter; |
| import java.io.Reader; |
| import java.util.Map; |
| |
| import javax.script.AbstractScriptEngine; |
| import javax.script.Bindings; |
| import javax.script.ScriptContext; |
| import javax.script.ScriptEngineFactory; |
| import javax.script.ScriptException; |
| |
| import com.cedarsoftware.util.io.JsonReader; |
| import com.github.jknack.handlebars.Handlebars; |
| import com.github.jknack.handlebars.Template; |
| import com.github.jknack.handlebars.helper.StringHelpers; |
| |
| import org.apache.commons.io.IOUtils; |
| import org.apache.sling.api.resource.Resource; |
| import org.apache.sling.api.scripting.SlingBindings; |
| import org.apache.sling.servlethelpers.internalrequests.ServletInternalRequest; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** Minimal script engine for server-side rendering |
| * using Handlebars templates. Might need some changes if |
| * we want to make it general-purpose, for now it's a quick |
| * implementation just for this demo. |
| * |
| * The JSON representation of the current Resource is retrieved |
| * using an internal request with the Resource path + ".json", and |
| * the result converted to a Handlebars-friendly Map of Maps. |
| * |
| * See https://github.com/jknack/handlebars.java for Handlebars docs |
| */ |
| public class HandlebarsScriptEngine extends AbstractScriptEngine { |
| |
| private final Logger log = LoggerFactory.getLogger(getClass()); |
| private final HandlebarsScriptEngineFactory factory; |
| |
| public HandlebarsScriptEngine(HandlebarsScriptEngineFactory factory) { |
| this.factory = factory; |
| } |
| |
| @Override |
| public Object eval(String script, ScriptContext context) throws ScriptException { |
| final Resource resource = (Resource) context.getBindings(ScriptContext.ENGINE_SCOPE).get(SlingBindings.RESOURCE); |
| final PrintWriter out = (PrintWriter) context.getBindings(ScriptContext.ENGINE_SCOPE).get(SlingBindings.OUT); |
| |
| try { |
| final Handlebars handlebars = setupHandlebars(); |
| final Template template = handlebars.compileInline(script); |
| out.println(template.apply(getData(resource))); |
| } catch(IOException ioe) { |
| final ScriptException up = new ScriptException("IOException in eval"); |
| up.initCause(ioe); |
| throw up; |
| } |
| return null; |
| } |
| |
| private Handlebars setupHandlebars() { |
| final Handlebars result = new Handlebars(); |
| result.registerHelpers(StringHelpers.class); |
| return result; |
| } |
| |
| /** We might do this with a BindingsValuesProvider? */ |
| private Map<?, ?> getData(Resource r) throws ScriptException { |
| // Request resource.json and convert the result to Maps |
| String jsonString = null; |
| try { |
| jsonString = |
| new ServletInternalRequest(factory.getServletResolver(), r) |
| .withExtension("json") |
| .execute() |
| .getResponseAsString() |
| ; |
| } catch(Exception e) { |
| final ScriptException up = new ScriptException("Internal request failed"); |
| up.initCause(e); |
| log.info("getData() failed", up); |
| throw up; |
| } |
| final Map<?, ?> result = JsonReader.jsonToMaps(jsonString); |
| log.debug("getData() returns a Map with {} keys", result.keySet().size()); |
| return result; |
| } |
| |
| @Override |
| public Object eval(Reader reader, ScriptContext context) throws ScriptException { |
| try { |
| return eval(IOUtils.toString(reader), context); |
| } catch(IOException ioe) { |
| final ScriptException up = new ScriptException("IOException in eval"); |
| up.initCause(ioe); |
| throw up; |
| } |
| } |
| |
| @Override |
| public Bindings createBindings() { |
| return null; |
| } |
| |
| @Override |
| public ScriptEngineFactory getFactory() { |
| return factory; |
| } |
| } |