homework.week3.course.BlogPostDAO.java Source code

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Here is the source code for homework.week3.course.BlogPostDAO.java

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/*
 * 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 homework.week3.course;

import com.mongodb.BasicDBList;
import com.mongodb.BasicDBObject;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;
import com.mongodb.QueryBuilder;
import com.mongodb.WriteResult;
import com.sun.org.apache.bcel.internal.generic.ACONST_NULL;

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
        QueryBuilder findQuery = QueryBuilder.start("permalink").is(permalink);
        DBCursor cur = postsCollection.find(findQuery.get());
        post = cur.hasNext() ? cur.next() : null;
        return post;
    }

    // Return a list of posts in descending order. Limit determines
    // how many posts are returned.
    public List<DBObject> findByDateDescending(int limit) {

        List<DBObject> posts = null;
        // XXX HW 3.2, Work Here
        // Return a list of DBObjects, each one a post from the posts collection
        QueryBuilder sortQuery = QueryBuilder.start("date").is(-1);
        DBCursor cursor = postsCollection.find().sort(sortQuery.get()).limit(limit);
        posts = cursor.toArray();
        return posts;
    }

    public String addPost(String title, String body, List 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();
        // 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
        post = post.append("title", title).append("author", username).append("tags", tags).append("body", body)
                .append("permalink", permalink).append("date", new Date()).append("comments", new BasicDBList());

        postsCollection.save(post);

        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 post = findByPermalink(permalink);

        BasicDBObject comment = new BasicDBObject();
        comment = comment.append("author", name).append("body", body);
        if (email != null) {
            comment = comment.append("email", email);
        }

        BasicDBList comments = (BasicDBList) post.get("comments");
        comments.add(comment);

        postsCollection.save(post);
    }

}