course.BlogPostDAO.java Source code

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Here is the source code for 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 course;

import com.mongodb.*;
import com.sun.org.apache.bcel.internal.generic.ACONST_NULL;
import freemarker.template.SimpleHash;
import org.bson.types.ObjectId;
import org.joda.time.DateTime;

import java.util.*;

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  ~> Done
        //post = QueryBuilder.start("permalink").is(permalink).get();
        BasicDBObject thePost = new BasicDBObject();
        thePost.put("permalink", permalink);
        post = postsCollection.findOne(thePost);
        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
        posts = new ArrayList<DBObject>();
        DBCursor cursor = postsCollection.find().sort(new BasicDBObject("_id", -1)).limit(limit);
        while (cursor.hasNext()) {
            posts.add(cursor.next());
        }
        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();

        // 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
        BasicDBObject post = new BasicDBObject();
        post.put("title", title);
        post.put("body", body);
        post.put("tags", tags);
        post.put("author", username);
        post.put("permalink", permalink);
        post.put("comments", new ArrayList<String>());
        DateTime dt = new DateTime();
        post.put("date", dt.toString("MMM d, yyyy h:mm:ss a"));
        postsCollection.insert(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
        BasicDBObject comment = new BasicDBObject();
        comment.put("author", name);
        if (!(email == null))
            comment.put("email", email);
        comment.put("body", body);
        DBObject post = findByPermalink(permalink);
        // $push operator appends a specified value to an array.
        BasicDBObject updateCommand = new BasicDBObject("$push", new BasicDBObject("comments", comment));
        postsCollection.update(post, updateCommand);

    }

}