Java tutorial
/* * Copyright (c) 2008 - 2013 10gen, Inc. <http://10gen.com> * * 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.andiandy.m101j.week3.hw2_3; import com.mongodb.*; import java.util.ArrayList; import java.util.Date; import java.util.List; public class BlogPostDAO { DBCollection postsCollection; public BlogPostDAO(final DB blogDatabase) { postsCollection = blogDatabase.getCollection("posts"); } // Return a single post corresponding to a permalink public DBObject findByPermalink(String permalink) { DBObject post = null; // XXX HW 3.2, Work Here DBObject query = QueryBuilder.start("permalink").is(permalink).get(); post = postsCollection.find(query).next(); return post; } // Return a list of posts in descending order. Limit determines // how many posts are returned. public List<DBObject> findByDateDescending(int limit) { DBCursor cursor = postsCollection.find().sort(new BasicDBObject("date", -1)).limit(limit); List<DBObject> posts = cursor.toArray(); // XXX HW 3.2, Work Here // Return a list of DBObjects, each one a post from the posts collection return posts; } public String addPost(String title, String body, List<String> tags, String username) { System.out.println("inserting blog entry " + title + " " + body); String permalink = title.replaceAll("\\s", "_"); // whitespace becomes _ permalink = permalink.replaceAll("\\W", ""); // get rid of non alphanumeric permalink = permalink.toLowerCase(); BasicDBObject post = new BasicDBObject(); post.append("title", title); post.append("author", username); post.append("body", body); post.append("permalink", permalink); post.append("tags", tags); post.append("comments", new ArrayList<String>()); post.append("date", new Date()); postsCollection.insert(post); // XXX HW 3.2, Work Here // Remember that a valid post has the following keys: // author, body, permalink, tags, comments, date // // A few hints: // - Don't forget to create an empty list of comments // - for the value of the date key, today's datetime is fine. // - tags are already in list form that implements suitable interface. // - we created the permalink for you above. // Build the post object and insert it return permalink; } // White space to protect the innocent // Append a comment to a blog post public void addPostComment(final String name, final String email, final String body, final String permalink) { // XXX HW 3.3, Work Here // Hints: // - email is optional and may come in NULL. Check for that. // - best solution uses an update command to the database and a suitable // operator to append the comment on to any existing list of comments DBObject query = QueryBuilder.start("permalink").is(permalink).get(); DBObject post = postsCollection.find(query).next(); BasicDBObject comment = new BasicDBObject(); comment.append("author", name); if (email != null) { comment.append("email", email); } comment.append("body", body); post.put("comments", comment); postsCollection.update(query, new BasicDBObject("$push", new BasicDBObject("comments", comment))); } }