course.week3.BlogPostDAO.java Source code

Introduction

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

Source

/*
 * 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.week3;

import com.mongodb.*;
import com.sun.org.apache.bcel.internal.generic.ACONST_NULL;

import java.util.ArrayList;
import java.util.Arrays;
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;
        DBObject query = QueryBuilder.start("permalink").is(permalink).get();
        // XXX HW 3.2,  Work Here
        post = postsCollection.findOne(query);

        return post;
    }

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

        DBCursor objects = postsCollection.find().sort(new BasicDBObject("date", 1)).limit(limit);
        List<DBObject> posts = objects.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 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().append("title", title).append("body", body).append("tags", tags)
                .append("author", username).append("date", new Date()).append("comments", new ArrayList())
                .append("permalink", permalink);
        // 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

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

        DBObject query = QueryBuilder.start("permalink").is(permalink).get();
        DBObject update = new BasicDBObject("$push", new BasicDBObject("comments", object));

        postsCollection.update(query, update);

    }

}