.NET中使用Redis (二)

jopen 10年前發布 | 39K 次閱讀 Redis NoSQL數據庫
很久以前寫了一篇文章 .NET中使用Redis 介紹了如何安裝Redis服務端，以及如何在.NET中調用Redis讀取數據。本文簡單介紹如何設計NoSQL數據庫，以及如何使用Redis來存儲對象。
和傳統的關系型數據庫不同，NoSQL大部分都是以鍵值對存儲在內存中的，我們不能直接把RDBMS里面的一些做法直接移植到NoSQL中來，一個最主要的原因是，在NoSQL中缺少RDBMS中的一些諸如join ,union以及一些在關系型數據庫中效率很高的執行語句，這些在NoSQL不能很好的支持，或者說效率低。
下文首先通過例子介紹在SQLServer中設計一個DB系統以及與NoSQL環境中設計一個DB的區別，最后演示如何在Redis中對數據進行讀寫操作。
一個簡單的博客系統

假設我們要設計一個簡單的博客系統，用戶可以注冊一個博客(Blog)，然后可以在上面寫文章(Post)，文章可以分類(Category)以及添加標簽(Tag)，用戶可以對文章進行評論(Comment)。
在該系統中，我們需要實現，如下基本功能：
首頁：顯示所有人的博客
首頁：顯示最近的所有發表的文章
首頁：顯示所有的最近的評論
首頁：顯示博客的標簽云
首頁：顯示所有的分類
文章頁面：顯示文章以及所有的評論
文章頁面：添加評論
標簽頁面：顯示所有標簽以及標簽對應的文章
分類頁面：顯示所有分類以及分類對應的文章
如果在SQLServer中，相信很簡單就可以設計出這樣一個DB了。
在NoSQL環境中，我們不能直接將上面的結構搬進來，所以需要根據需求重新設計我們的模型。
定義實體

在NoSQL環境下，所有的數據其實都是以key和value的形式存儲在內存中的，value通常是序列化為字符串保存的。我們使用redis客戶端的時候，可以直接將對象存儲，這些客戶端在內部實現上幫助我們進行了序列化。所以第一步就是需要定義實體模型：
首先來看User實體：
public class User{
    public User()
    {
        this.BlogIds = new List<long>();
    }

</span><span style="color:blue;">public long </span><span style="color:black;">Id { </span><span style="color:blue;">get</span><span style="color:black;">; </span><span style="color:blue;">set</span><span style="color:black;">; }
</span><span style="color:blue;">public string </span><span style="color:black;">Name { </span><span style="color:blue;">get</span><span style="color:black;">; </span><span style="color:blue;">set</span><span style="color:black;">; }
</span><span style="color:blue;">public </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:blue;">long</span><span style="color:black;">> BlogIds { </span><span style="color:blue;">get</span><span style="color:black;">; </span><span style="color:blue;">set</span><span style="color:black;">; }

}</span></pre> 
User實體中，包含了用戶的Id，Name以及博客的Id。

然后Blog實體:

public class Blog{
    public Blog()
    {
        this.Tags = new List<string>();
        this.BlogPostIds = new List<long>();
    }

</span><span style="color:blue;">public long </span><span style="color:black;">Id { </span><span style="color:blue;">get</span><span style="color:black;">; </span><span style="color:blue;">set</span><span style="color:black;">; }
</span><span style="color:blue;">public long </span><span style="color:black;">UserId { </span><span style="color:blue;">get</span><span style="color:black;">; </span><span style="color:blue;">set</span><span style="color:black;">; }
</span><span style="color:blue;">public string </span><span style="color:black;">UserName { </span><span style="color:blue;">get</span><span style="color:black;">; </span><span style="color:blue;">set</span><span style="color:black;">; }
</span><span style="color:blue;">public </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:blue;">string</span><span style="color:black;">> Tags { </span><span style="color:blue;">get</span><span style="color:black;">; </span><span style="color:blue;">set</span><span style="color:black;">; }
</span><span style="color:blue;">public </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:blue;">long</span><span style="color:black;">> BlogPostIds { </span><span style="color:blue;">get</span><span style="color:black;">; </span><span style="color:blue;">set</span><span style="color:black;">; }

}</span></pre> 
包含了標簽Tag，以及文章Id列表。

文章BolgPost實體：

public class BlogPost{
    public BlogPost()
    {
        this.Categories = new List<string>();
        this.Tags = new List<string>();
        this.Comments = new List<BlogPostComment>();
    }

</span><span style="color:blue;">public long </span><span style="color:black;">Id { </span><span style="color:blue;">get</span><span style="color:black;">; </span><span style="color:blue;">set</span><span style="color:black;">; }
</span><span style="color:blue;">public long </span><span style="color:black;">BlogId { </span><span style="color:blue;">get</span><span style="color:black;">; </span><span style="color:blue;">set</span><span style="color:black;">; }
</span><span style="color:blue;">public string </span><span style="color:black;">Title { </span><span style="color:blue;">get</span><span style="color:black;">; </span><span style="color:blue;">set</span><span style="color:black;">; }
</span><span style="color:blue;">public string </span><span style="color:black;">Content { </span><span style="color:blue;">get</span><span style="color:black;">; </span><span style="color:blue;">set</span><span style="color:black;">; }
</span><span style="color:blue;">public </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:blue;">string</span><span style="color:black;">> Categories { </span><span style="color:blue;">get</span><span style="color:black;">; </span><span style="color:blue;">set</span><span style="color:black;">; }
</span><span style="color:blue;">public </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:blue;">string</span><span style="color:black;">> Tags { </span><span style="color:blue;">get</span><span style="color:black;">; </span><span style="color:blue;">set</span><span style="color:black;">; }
</span><span style="color:blue;">public </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:#2b91af;">BlogPostComment</span><span style="color:black;">> Comments { </span><span style="color:blue;">get</span><span style="color:black;">; </span><span style="color:blue;">set</span><span style="color:black;">; }

}</span></pre> 
包含了一篇文章的基本信息，如文章分類，文章標簽，文章的評論。

最后看評論BlogPostComment實體：

public class BlogPostComment{
    public string Content { get; set; }
    public DateTime CreatedDate { get; set; }
}
  

具體實現

實體定義好了之后，我們就可以開始具體實現了。為了演示，這里通過單元測試的方式實現具體功能：

首先要把Redis的服務端啟動起來，然后在工程中新建一個Redis客戶端，之后的所有操作都通過這個客戶端進行。

[TestFixture, Explicit, Category("Integration")]public class BlogPostExample{
    readonly RedisClient redis = new RedisClient("localhost");

[</span><span style="color:#2b91af;">SetUp</span><span style="color:black;">]
</span><span style="color:blue;">public void </span><span style="color:black;">OnBeforeEachTest()
{
    redis.FlushAll();
    InsertTestData();
}

}</span></pre> 
在單元測試的SetUp中，我們插入一些模擬數據，插入數據的方法為InsetTestData方法：

public void InsertTestData()
{
    var redisUsers = redis.As<User>();
    var redisBlogs = redis.As<Blog>();
    var redisBlogPosts = redis.As<BlogPost>();

</span><span style="color:blue;">var </span><span style="color:black;">yangUser = </span><span style="color:blue;">new </span><span style="color:#2b91af;">User </span><span style="color:black;">{ Id = redisUsers.GetNextSequence(), Name = </span><span style="color:#a31515;">"Eric Yang" </span><span style="color:black;">};
</span><span style="color:blue;">var </span><span style="color:black;">zhangUser = </span><span style="color:blue;">new </span><span style="color:#2b91af;">User </span><span style="color:black;">{ Id = redisUsers.GetNextSequence(), Name = </span><span style="color:#a31515;">"Fish Zhang" </span><span style="color:black;">};

</span><span style="color:blue;">var </span><span style="color:black;">yangBlog = </span><span style="color:blue;">new </span><span style="color:#2b91af;">Blog
</span><span style="color:black;">{
    Id = redisBlogs.GetNextSequence(),
    UserId = yangUser.Id,
    UserName = yangUser.Name,
    Tags = </span><span style="color:blue;">new </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:blue;">string</span><span style="color:black;">> { </span><span style="color:#a31515;">"Architecture"</span><span style="color:black;">, </span><span style="color:#a31515;">".NET"</span><span style="color:black;">, </span><span style="color:#a31515;">"Databases" </span><span style="color:black;">},
};

</span><span style="color:blue;">var </span><span style="color:black;">zhangBlog = </span><span style="color:blue;">new </span><span style="color:#2b91af;">Blog
</span><span style="color:black;">{
    Id = redisBlogs.GetNextSequence(),
    UserId = zhangUser.Id,
    UserName = zhangUser.Name,
    Tags = </span><span style="color:blue;">new </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:blue;">string</span><span style="color:black;">> { </span><span style="color:#a31515;">"Architecture"</span><span style="color:black;">, </span><span style="color:#a31515;">".NET"</span><span style="color:black;">, </span><span style="color:#a31515;">"Databases" </span><span style="color:black;">},
};

</span><span style="color:blue;">var </span><span style="color:black;">blogPosts = </span><span style="color:blue;">new </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:#2b91af;">BlogPost</span><span style="color:black;">>
{
    </span><span style="color:blue;">new </span><span style="color:#2b91af;">BlogPost
    </span><span style="color:black;">{
        Id = redisBlogPosts.GetNextSequence(),
        BlogId = yangBlog.Id,
        Title = </span><span style="color:#a31515;">"Memcache"</span><span style="color:black;">,
        Categories = </span><span style="color:blue;">new </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:blue;">string</span><span style="color:black;">> { </span><span style="color:#a31515;">"NoSQL"</span><span style="color:black;">, </span><span style="color:#a31515;">"DocumentDB" </span><span style="color:black;">},
        Tags = </span><span style="color:blue;">new </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:blue;">string</span><span style="color:black;">> {</span><span style="color:#a31515;">"Memcache"</span><span style="color:black;">, </span><span style="color:#a31515;">"NoSQL"</span><span style="color:black;">, </span><span style="color:#a31515;">"JSON"</span><span style="color:black;">, </span><span style="color:#a31515;">".NET"</span><span style="color:black;">} ,
        Comments = </span><span style="color:blue;">new </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:#2b91af;">BlogPostComment</span><span style="color:black;">>
        {
            </span><span style="color:blue;">new </span><span style="color:#2b91af;">BlogPostComment </span><span style="color:black;">{ Content = </span><span style="color:#a31515;">"First Comment!"</span><span style="color:black;">, CreatedDate = </span><span style="color:#2b91af;">DateTime</span><span style="color:black;">.UtcNow,},
            </span><span style="color:blue;">new </span><span style="color:#2b91af;">BlogPostComment </span><span style="color:black;">{ Content = </span><span style="color:#a31515;">"Second Comment!"</span><span style="color:black;">, CreatedDate = </span><span style="color:#2b91af;">DateTime</span><span style="color:black;">.UtcNow,},
        }
    },
    </span><span style="color:blue;">new </span><span style="color:#2b91af;">BlogPost
    </span><span style="color:black;">{
        Id = redisBlogPosts.GetNextSequence(),
        BlogId = zhangBlog.Id,
        Title = </span><span style="color:#a31515;">"Redis"</span><span style="color:black;">,
        Categories = </span><span style="color:blue;">new </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:blue;">string</span><span style="color:black;">> { </span><span style="color:#a31515;">"NoSQL"</span><span style="color:black;">, </span><span style="color:#a31515;">"Cache" </span><span style="color:black;">},
        Tags = </span><span style="color:blue;">new </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:blue;">string</span><span style="color:black;">> {</span><span style="color:#a31515;">"Redis"</span><span style="color:black;">, </span><span style="color:#a31515;">"NoSQL"</span><span style="color:black;">, </span><span style="color:#a31515;">"Scalability"</span><span style="color:black;">, </span><span style="color:#a31515;">"Performance"</span><span style="color:black;">},
        Comments = </span><span style="color:blue;">new </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:#2b91af;">BlogPostComment</span><span style="color:black;">>
        {
            </span><span style="color:blue;">new </span><span style="color:#2b91af;">BlogPostComment </span><span style="color:black;">{ Content = </span><span style="color:#a31515;">"First Comment!"</span><span style="color:black;">, CreatedDate = </span><span style="color:#2b91af;">DateTime</span><span style="color:black;">.UtcNow,}
        }
    },
    </span><span style="color:blue;">new </span><span style="color:#2b91af;">BlogPost
    </span><span style="color:black;">{
        Id = redisBlogPosts.GetNextSequence(),
        BlogId = yangBlog.Id,
        Title = </span><span style="color:#a31515;">"Cassandra"</span><span style="color:black;">,
        Categories = </span><span style="color:blue;">new </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:blue;">string</span><span style="color:black;">> { </span><span style="color:#a31515;">"NoSQL"</span><span style="color:black;">, </span><span style="color:#a31515;">"Cluster" </span><span style="color:black;">},
        Tags = </span><span style="color:blue;">new </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:blue;">string</span><span style="color:black;">> {</span><span style="color:#a31515;">"Cassandra"</span><span style="color:black;">, </span><span style="color:#a31515;">"NoSQL"</span><span style="color:black;">, </span><span style="color:#a31515;">"Scalability"</span><span style="color:black;">, </span><span style="color:#a31515;">"Hashing"</span><span style="color:black;">},
        Comments = </span><span style="color:blue;">new </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:#2b91af;">BlogPostComment</span><span style="color:black;">>
        {
            </span><span style="color:blue;">new </span><span style="color:#2b91af;">BlogPostComment </span><span style="color:black;">{ Content = </span><span style="color:#a31515;">"First Comment!"</span><span style="color:black;">, CreatedDate = </span><span style="color:#2b91af;">DateTime</span><span style="color:black;">.UtcNow,}
        }
    },
    </span><span style="color:blue;">new </span><span style="color:#2b91af;">BlogPost
    </span><span style="color:black;">{
        Id = redisBlogPosts.GetNextSequence(),
        BlogId = zhangBlog.Id,
        Title = </span><span style="color:#a31515;">"Couch Db"</span><span style="color:black;">,
        Categories = </span><span style="color:blue;">new </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:blue;">string</span><span style="color:black;">> { </span><span style="color:#a31515;">"NoSQL"</span><span style="color:black;">, </span><span style="color:#a31515;">"DocumentDB" </span><span style="color:black;">},
        Tags = </span><span style="color:blue;">new </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:blue;">string</span><span style="color:black;">> {</span><span style="color:#a31515;">"CouchDb"</span><span style="color:black;">, </span><span style="color:#a31515;">"NoSQL"</span><span style="color:black;">, </span><span style="color:#a31515;">"JSON"</span><span style="color:black;">},
        Comments = </span><span style="color:blue;">new </span><span style="color:#2b91af;">List</span><span style="color:black;"><</span><span style="color:#2b91af;">BlogPostComment</span><span style="color:black;">>
        {
            </span><span style="color:blue;">new </span><span style="color:#2b91af;">BlogPostComment </span><span style="color:black;">{Content = </span><span style="color:#a31515;">"First Comment!"</span><span style="color:black;">, CreatedDate = </span><span style="color:#2b91af;">DateTime</span><span style="color:black;">.UtcNow,}
        }
    },
};

yangUser.BlogIds.Add(yangBlog.Id);
yangBlog.BlogPostIds.AddRange(blogPosts.Where(x => x.BlogId == yangBlog.Id).Map(x => x.Id));

zhangUser.BlogIds.Add(zhangBlog.Id);
zhangBlog.BlogPostIds.AddRange(blogPosts.Where(x => x.BlogId == zhangBlog.Id).Map(x => x.Id));

redisUsers.Store(yangUser);
redisUsers.Store(zhangUser);
redisBlogs.StoreAll(</span><span style="color:blue;">new</span><span style="color:black;">[] { yangBlog, zhangBlog });
redisBlogPosts.StoreAll(blogPosts);

}</span></pre> 
在方法中，首先在Redis中創建了三個強類型的IRedisTypedClient類型的對象redisUsers,redisBlogs,redisBlogPosts來保存用戶信息，博客信息，和文字信息。

var yangUser = new User { Id = redisUsers.GetNextSequence(), Name = "Eric Yang" };
 在新建用戶的時候，因為Id是自增字段，所以直接調用redisUsers這個client的GetNextSequence()方法就可以獲得一個自增的Id。

創建完用戶之后，接著創建博客信息:

var yangBlog = new Blog{
    Id = redisBlogs.GetNextSequence(),
    UserId = yangUser.Id,
    UserName = yangUser.Name,
    Tags = new List<string> { "Architecture", ".NET", "Databases" },
};
 該博客有幾個標簽。

在接著創建該博客上發表的若干篇文章：

var blogPosts = new List<BlogPost>
{
    new BlogPost
    {
        Id = redisBlogPosts.GetNextSequence(),
        BlogId = yangBlog.Id,
        Title = "Memcache",
        Categories = new List<string> { "NoSQL", "DocumentDB" },
        Tags = new List<string> {"Memcache", "NoSQL", "JSON", ".NET"} ,
        Comments = new List<BlogPostComment>
        {
            new BlogPostComment { Content = "First Comment!", CreatedDate = DateTime.UtcNow,},
            new BlogPostComment { Content = "Second Comment!", CreatedDate = DateTime.UtcNow,},
        }
    }
}
 每一篇文章都有分類和標簽，以及評論。

然后需要給user的BlogsIds和blog的BlogPostIds賦值

yangUser.BlogIds.Add(yangBlog.Id);
yangBlog.BlogPostIds.AddRange(blogPosts.Where(x => x.BlogId == yangBlog.Id).Map(x => x.Id));
 最后需要把這些信息保存到redis中。

//保存用戶信息 redisUsers.Store(yangUser);
redisUsers.Store(zhangUser);//保存博客信息redisBlogs.StoreAll(new[] { yangBlog, zhangBlog });//保存所有的文章信息redisBlogPosts.StoreAll(blogPosts);
 現在，利用Redis Desktop Manager，可以查看Reidis中存儲的數據：


數據準備好了之后，可以實現前面列出的一系列方法了：

顯示所有博客

該方法在GetAllBlogs中，實現如下：

[Test]public void Show_a_list_of_blogs()
{
    var redisBlogs = redis.As<Blog>();
    var blogs = redisBlogs.GetAll();
    blogs.PrintDump();
}
 只需要調用GetAll方法即可獲取內存中的所有指定類型的對象。

輸出結果為：

[
    {

    Id: 1,
    UserId: 1,
    UserName: Eric Yang,
    Tags: 
    [
        Architecture,
        .NET,
        Databases
    ],
    BlogPostIds: 
    [
        1,
        3
    ]
},
{
    Id: 2,
    UserId: 2,
    UserName: Fish Zhang,
    Tags: 
    [
        Architecture,
        .NET,
        Databases
    ],
    BlogPostIds: 
    [
        2,
        4
    ]
}

]</span></pre> 
顯示最近發表的文章和評論

實現如下:

[Test]public void Show_a_list_of_recent_posts_and_comments()
{
    //Get strongly-typed clients
    var redisBlogPosts = redis.As<BlogPost>();
    var redisComments = redis.As<BlogPostComment>();
    {
        //To keep this example let's pretend this is a new list of blog posts
        var newIncomingBlogPosts = redisBlogPosts.GetAll();

    </span><span style="color:green;">//Let's get back an IList<BlogPost> wrapper around a Redis server-side List.
    </span><span style="color:blue;">var </span><span style="color:black;">recentPosts = redisBlogPosts.Lists[</span><span style="color:#a31515;">"urn:BlogPost:RecentPosts"</span><span style="color:black;">];
    </span><span style="color:blue;">var </span><span style="color:black;">recentComments = redisComments.Lists[</span><span style="color:#a31515;">"urn:BlogPostComment:RecentComments"</span><span style="color:black;">];

    </span><span style="color:blue;">foreach </span><span style="color:black;">(</span><span style="color:blue;">var </span><span style="color:black;">newBlogPost </span><span style="color:blue;">in </span><span style="color:black;">newIncomingBlogPosts)
    {
        </span><span style="color:green;">//Prepend the new blog posts to the start of the 'RecentPosts' list
        </span><span style="color:black;">recentPosts.Prepend(newBlogPost);

        </span><span style="color:green;">//Prepend all the new blog post comments to the start of the 'RecentComments' list
        </span><span style="color:black;">newBlogPost.Comments.ForEach(recentComments.Prepend);
    }

    </span><span style="color:green;">//Make this a Rolling list by only keep the latest 3 posts and comments
    </span><span style="color:black;">recentPosts.Trim(0, 2);
    recentComments.Trim(0, 2);

    </span><span style="color:green;">//Print out the last 3 posts:
    </span><span style="color:black;">recentPosts.GetAll().PrintDump();
  </span><span style="color:black;">recentComments.GetAll().PrintDump();
 </span><span style="color:black;">}

}</span></pre> 
方法中定義了兩個key為urn:BlogPost:RecentPosts 和 urn:BlogPostComment:RecentComments的 List對象來保存最近發表的文章和評論：recentPosts.Prepend(newBlogPost)方法表示將新創建的文章插到 recentPosts列表的最前面。

Trim方法表示僅保留n個在集合中。

顯示博客的標簽云

顯示博客的標簽云方法如下：

[Test]public void Show_a_TagCloud()
{
    //Get strongly-typed clients
    var redisBlogPosts = redis.As<BlogPost>();
    var newIncomingBlogPosts = redisBlogPosts.GetAll();

</span><span style="color:blue;">foreach </span><span style="color:black;">(</span><span style="color:blue;">var </span><span style="color:black;">newBlogPost </span><span style="color:blue;">in </span><span style="color:black;">newIncomingBlogPosts)
{
    </span><span style="color:green;">//For every tag in each new blog post, increment the number of times each Tag has occurred 
    </span><span style="color:black;">newBlogPost.Tags.ForEach(x =>
        redis.IncrementItemInSortedSet(</span><span style="color:#a31515;">"urn:TagCloud"</span><span style="color:black;">, x, 1));
}

</span><span style="color:green;">//Show top 5 most popular tags with their scores
</span><span style="color:blue;">var </span><span style="color:black;">tagCloud = redis.GetRangeWithScoresFromSortedSetDesc(</span><span style="color:#a31515;">"urn:TagCloud"</span><span style="color:black;">, 0, 4);
tagCloud.PrintDump();

}</span></pre> 
顯示標簽云的實現，用到了redis中的SortedSet，IncrementItemInSortedSet表示如果有相同的話，值加一，GetRangeWithScoresFromSortedSetDesc方法，獲取某一key的前5個對象。

顯示所有的分類

顯示所有的分類用到了Set對象。

[Test]public void Show_all_Categories()
{
    var redisBlogPosts = redis.As<BlogPost>();
    var blogPosts = redisBlogPosts.GetAll();

</span><span style="color:blue;">foreach </span><span style="color:black;">(</span><span style="color:blue;">var </span><span style="color:black;">blogPost </span><span style="color:blue;">in </span><span style="color:black;">blogPosts)
{
    blogPost.Categories.ForEach(x =>
            redis.AddItemToSet(</span><span style="color:#a31515;">"urn:Categories"</span><span style="color:black;">, x));
}

</span><span style="color:blue;">var </span><span style="color:black;">uniqueCategories = redis.GetAllItemsFromSet(</span><span style="color:#a31515;">"urn:Categories"</span><span style="color:black;">);
uniqueCategories.PrintDump();

}</span></pre> 
顯示文章以及其評論

實現如下:

[Test]public void Show_post_and_all_comments()
{
    //There is nothing special required here as since comments are Key Value Objects 
    //they are stored and retrieved with the post
    var postId = 1;
    var redisBlogPosts = redis.As<BlogPost>();
    var selectedBlogPost = redisBlogPosts.GetById(postId.ToString());

selectedBlogPost.PrintDump();

}</span></pre> 
只需要把postId傳進去就可以通過GetById的方法獲取內存中的對象.

添加評論

首先根據PostId獲取BlogPost，然后在Comment屬性中添加一個BlogPostComment對象，然后在保存改BlogPost.

[Test]public void Add_comment_to_existing_post()
{
    var postId = 1;
    var redisBlogPosts = redis.As<BlogPost>();
    var blogPost = redisBlogPosts.GetById(postId.ToString());
    blogPost.Comments.Add(
        new BlogPostComment { Content = "Third Post!", CreatedDate = DateTime.UtcNow });
    redisBlogPosts.Store(blogPost);

</span><span style="color:blue;">var </span><span style="color:black;">refreshBlogPost = redisBlogPosts.GetById(postId.ToString());
refreshBlogPost.PrintDump();

}</span></pre> 
顯示分類以及分類對應的文章

[Test]public void Show_all_Posts_for_the_DocumentDB_Category()
{
    var redisBlogPosts = redis.As<BlogPost>();
    var newIncomingBlogPosts = redisBlogPosts.GetAll();

</span><span style="color:blue;">foreach </span><span style="color:black;">(</span><span style="color:blue;">var </span><span style="color:black;">newBlogPost </span><span style="color:blue;">in </span><span style="color:black;">newIncomingBlogPosts)
{
    </span><span style="color:green;">//For each post add it's Id into each of it's 'Cateogry > Posts' index
    </span><span style="color:black;">newBlogPost.Categories.ForEach(x =>
            redis.AddItemToSet(</span><span style="color:#a31515;">"urn:Category:" </span><span style="color:black;">+ x, newBlogPost.Id.ToString()));
}

</span><span style="color:green;">//Retrieve all the post ids for the category you want to view
</span><span style="color:blue;">var </span><span style="color:black;">documentDbPostIds = redis.GetAllItemsFromSet(</span><span style="color:#a31515;">"urn:Category:DocumentDB"</span><span style="color:black;">);

</span><span style="color:green;">//Make a batch call to retrieve all the posts containing the matching ids 
//(i.e. the DocumentDB Category posts)
</span><span style="color:blue;">var </span><span style="color:black;">documentDbPosts = redisBlogPosts.GetByIds(documentDbPostIds);

documentDbPosts.PrintDump();

}</span></pre> 
這里首先把所有的文章按照標簽新建Set，把相同的分類的文章放到一個Set中，最后根據key即可查找到相應的集合。

總結

本文利用一個簡單的博客系統，簡要介紹了如何利用Redis存儲和獲取復雜的數據。由于本文主要為了演示如何與Redis進行交互，所以實體設計的很簡陋，沒有按照DDD的思想進行設計，在某些設計方面沒有遵循前文淺談依賴注入中使用的原理和方法，后面會寫文章對該系統進行重構以使之更加完善。

希望本文對您了解如何利用Redis存儲復雜對象有所幫助。

 

參考資料


Designing NoSql Database

Migrations Using Schemaless NoSql

That No SQL Thing: The relational modeling anti pattern in document databases
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</div>
作者： yangecnu（ yangecnu's Blog on 博客園） 

出處： http://www.cnblogs.com/yangecnu/
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Redis NoSQL數據庫
.NET中使用Redis (二)

一個簡單的博客系統

定義實體

具體實現

顯示所有博客

顯示最近發表的文章和評論

顯示博客的標簽云

顯示所有的分類

顯示文章以及其評論

添加評論

顯示分類以及分類對應的文章

總結

相關經驗

相關資訊

相關文檔

目錄
