很久以前写了一篇文章 .NET中使用Redis 介绍了如何安装Redis服务端，以及如何在.NET中调用Redis读取数据。本文简单介绍如何设计NoSQL数据库，以及如何使用Redis来存储对象。

和传统的关系型数据库不同，NoSQL大部分都是以键值对存储在内存中的，我们不能直接把RDBMS里面的一些做法直接移植到NoSQL中来，一个最主要的原因是，在NoSQL中缺少RDBMS中的一些诸如join ,union以及一些在关系型数据库中效率很高的执行语句，这些在NoSQL不能很好的支持，或者说效率低。

下文首先通过例子介绍在SQLServer中设计一个DB系统以及与NoSQL环境中设计一个DB的区别，最后演示如何在Redis中对数据进行读写操作。

一个简单的博客系统

假设我们要设计一个简单的博客系统，用户可以注册一个博客(Blog)，然后可以在上面写文章(Post)，文章可以分类(Category)以及添加标签(Tag)，用户可以对文章进行评论(Comment)。

在该系统中，我们需要实现，如下基本功能：

  • 首页：显示所有人的博客
  • 首页：显示最近的所有发表的文章
  • 首页：显示所有的最近的评论
  • 首页：显示博客的标签云
  • 首页：显示所有的分类
  • 文章页面：显示文章以及所有的评论
  • 文章页面：添加评论
  • 标签页面：显示所有标签以及标签对应的文章
  • 分类页面：显示所有分类以及分类对应的文章

如果在SQLServer中，相信很简单就可以设计出这样一个DB了。

在NoSQL环境中，我们不能直接将上面的结构搬进来，所以需要根据需求重新设计我们的模型。

定义实体

在NoSQL环境下，所有的数据其实都是以key和value的形式存储在内存中的，value通常是序列化为字符串保存的。我们使用redis客户端的时候，可以直接将对象存储，这些客户端在内部实现上帮助我们进行了序列化。所以第一步就是需要定义实体模型：

首先来看User实体：

 
 
 
 
 
 

C#

 
public class User
{
public User()
{
this.BlogIds = new List<long>();
}

public long Id { get; set; }
public string Name { get; set; }
public List<long> BlogIds { get; set; }
}

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public class User
{
    public User()
    {
        this.BlogIds = new List<long>();
    }
 
    public long Id { get; set; }
    public string Name { get; set; }
    public List<long> BlogIds { get; set; }
}

User实体中，包含了用户的Id，Name以及博客的Id。

然后Blog实体:

 
 
 
 
 
 

C#

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

public long Id { get; set; }
public long UserId { get; set; }
public string UserName { get; set; }
public List<string> Tags { get; set; }
public List<long> BlogPostIds { get; set; }
}

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public class Blog
{
    public Blog()
    {
        this.Tags = new List<string>();
        this.BlogPostIds = new List<long>();
    }
 
    public long Id { get; set; }
    public long UserId { get; set; }
    public string UserName { get; set; }
    public List<string> Tags { get; set; }
    public List<long> BlogPostIds { get; set; }
}

包含了标签Tag，以及文章Id列表。

文章BolgPost实体：

 
 
 
 
 
 

C#

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

public long Id { get; set; }
public long BlogId { get; set; }
public string Title { get; set; }
public string Content { get; set; }
public List<string> Categories { get; set; }
public List<string> Tags { get; set; }
public List<BlogPostComment> Comments { get; set; }
}

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public class BlogPost
{
    public BlogPost()
    {
        this.Categories = new List<string>();
        this.Tags = new List<string>();
        this.Comments = new List<BlogPostComment>();
    }
 
    public long Id { get; set; }
    public long BlogId { get; set; }
    public string Title { get; set; }
    public string Content { get; set; }
    public List<string> Categories { get; set; }
    public List<string> Tags { get; set; }
    public List<BlogPostComment> Comments { get; set; }
}

包含了一篇文章的基本信息，如文章分类，文章标签，文章的评论。

最后看评论BlogPostComment实体：

 
 
 
 
 
 

C#

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

具体实现

实体定义好了之后，我们就可以开始具体实现了。为了演示，这里通过单元测试的方式实现具体功能：

首先要把Redis的服务端启动起来，然后在工程中新建一个Redis客户端，之后的所有操作都通过这个客户端进行。

 
 
 
 
 
 

C#

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

[SetUp]
public void OnBeforeEachTest()
{
redis.FlushAll();
InsertTestData();
}
}

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[TestFixture, Explicit, Category("Integration")]
public class BlogPostExample
{
    readonly RedisClient redis = new RedisClient("localhost");
 
    [SetUp]
    public void OnBeforeEachTest()
    {
        redis.FlushAll();
        InsertTestData();
    }
}

在单元测试的SetUp中，我们插入一些模拟数据，插入数据的方法为InsetTestData方法：

 
 
 
 
 
 

C#

使用 CTRL+C 复制，使用 CTRL+V 粘贴。
public void InsertTestData()
{
var redisUsers = redis.As<User>();
var redisBlogs = redis.As<Blog>();
var redisBlogPosts = redis.As<BlogPost>();

var yangUser = new User { Id = redisUsers.GetNextSequence(), Name = "Eric Yang" };
var zhangUser = new User { Id = redisUsers.GetNextSequence(), Name = "Fish Zhang" };

var yangBlog = new Blog
{
Id = redisBlogs.GetNextSequence(),
UserId = yangUser.Id,
UserName = yangUser.Name,
Tags = new List<string> { "Architecture", ".NET", "Databases" },
};

var zhangBlog = new Blog
{
Id = redisBlogs.GetNextSequence(),
UserId = zhangUser.Id,
UserName = zhangUser.Name,
Tags = new List<string> { "Architecture", ".NET", "Databases" },
};

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,},
}
},
new BlogPost
{
Id = redisBlogPosts.GetNextSequence(),
BlogId = zhangBlog.Id,
Title = "Redis",
Categories = new List<string> { "NoSQL", "Cache" },
Tags = new List<string> {"Redis", "NoSQL", "Scalability", "Performance"},
Comments = new List<BlogPostComment>
{
new BlogPostComment { Content = "First Comment!", CreatedDate = DateTime.UtcNow,}
}
},
new BlogPost
{
Id = redisBlogPosts.GetNextSequence(),
BlogId = yangBlog.Id,
Title = "Cassandra",
Categories = new List<string> { "NoSQL", "Cluster" },
Tags = new List<string> {"Cassandra", "NoSQL", "Scalability", "Hashing"},
Comments = new List<BlogPostComment>
{
new BlogPostComment { Content = "First Comment!", CreatedDate = DateTime.UtcNow,}
}
},
new BlogPost
{
Id = redisBlogPosts.GetNextSequence(),
BlogId = zhangBlog.Id,
Title = "Couch Db",
Categories = new List<string> { "NoSQL", "DocumentDB" },
Tags = new List<string> {"CouchDb", "NoSQL", "JSON"},
Comments = new List<BlogPostComment>
{
new BlogPostComment {Content = "First Comment!", CreatedDate = DateTime.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(new[] { yangBlog, zhangBlog });
redisBlogPosts.StoreAll(blogPosts);
}

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public void InsertTestData()
{
    var redisUsers = redis.As<User>();
    var redisBlogs = redis.As<Blog>();
    var redisBlogPosts = redis.As<BlogPost>();
 
    var yangUser = new User { Id = redisUsers.GetNextSequence(), Name = "Eric Yang" };
    var zhangUser = new User { Id = redisUsers.GetNextSequence(), Name = "Fish Zhang" };
 
    var yangBlog = new Blog
    {
        Id = redisBlogs.GetNextSequence(),
        UserId = yangUser.Id,
        UserName = yangUser.Name,
        Tags = new List<string> { "Architecture", ".NET", "Databases" },
    };
 
    var zhangBlog = new Blog
    {
        Id = redisBlogs.GetNextSequence(),
        UserId = zhangUser.Id,
        UserName = zhangUser.Name,
        Tags = new List<string> { "Architecture", ".NET", "Databases" },
    };
 
    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,},
            }
        },
        new BlogPost
        {
            Id = redisBlogPosts.GetNextSequence(),
            BlogId = zhangBlog.Id,
            Title = "Redis",
            Categories = new List<string> { "NoSQL", "Cache" },
            Tags = new List<string> {"Redis", "NoSQL", "Scalability", "Performance"},
            Comments = new List<BlogPostComment>
            {
                new BlogPostComment { Content = "First Comment!", CreatedDate = DateTime.UtcNow,}
            }
        },
        new BlogPost
        {
            Id = redisBlogPosts.GetNextSequence(),
            BlogId = yangBlog.Id,
            Title = "Cassandra",
            Categories = new List<string> { "NoSQL", "Cluster" },
            Tags = new List<string> {"Cassandra", "NoSQL", "Scalability", "Hashing"},
            Comments = new List<BlogPostComment>
            {
                new BlogPostComment { Content = "First Comment!", CreatedDate = DateTime.UtcNow,}
            }
        },
        new BlogPost
        {
            Id = redisBlogPosts.GetNextSequence(),
            BlogId = zhangBlog.Id,
            Title = "Couch Db",
            Categories = new List<string> { "NoSQL", "DocumentDB" },
            Tags = new List<string> {"CouchDb", "NoSQL", "JSON"},
            Comments = new List<BlogPostComment>
            {
                new BlogPostComment {Content = "First Comment!", CreatedDate = DateTime.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(new[] { yangBlog, zhangBlog });
    redisBlogPosts.StoreAll(blogPosts);
}

在方法中，首先在Redis中创建了三个强类型的IRedisTypedClient类型的对象redisUsers,redisBlogs,redisBlogPosts来保存用户信息，博客信息，和文字信息。

 
 
 
 
 
 

C#

 
var yangUser = new User { Id = redisUsers.GetNextSequence(), Name = "Eric Yang" };
1
var yangUser = new User { Id = redisUsers.GetNextSequence(), Name = "Eric Yang" };

在新建用户的时候，因为Id是自增字段，所以直接调用redisUsers这个client的GetNextSequence()方法就可以获得一个自增的Id。

创建完用户之后，接着创建博客信息:

 
 
 
 
 
 

C#

 
var yangBlog = new Blog
{
Id = redisBlogs.GetNextSequence(),
UserId = yangUser.Id,
UserName = yangUser.Name,
Tags = new List<string> { "Architecture", ".NET", "Databases" },
};
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var yangBlog = new Blog
{
    Id = redisBlogs.GetNextSequence(),
    UserId = yangUser.Id,
    UserName = yangUser.Name,
    Tags = new List<string> { "Architecture", ".NET", "Databases" },
};

该博客有几个标签。

在接着创建该博客上发表的若干篇文章：

 
 
 
 
 
 

C#

 
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,},
}
}
}
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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,},
        }
    }
}

每一篇文章都有分类和标签，以及评论。

然后需要给user的BlogsIds和blog的BlogPostIds赋值

 
 
 
 
 
 

C#

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

最后需要把这些信息保存到redis中。

 
 
 
 
 
 

C#

 
//保存用户信息
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);
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//保存用户信息
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);

现在，利用Redis Desktop Manager，可以查看Reidis中存储的数据：

数据准备好了之后，可以实现前面列出的一系列方法了：

显示所有博客

该方法在GetAllBlogs中，实现如下：

 
 
 
 
 
 

C#

 
[Test]
public void Show_a_list_of_blogs()
{
var redisBlogs = redis.As<Blog>();
var blogs = redisBlogs.GetAll();
blogs.PrintDump();
}
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[Test]
public void Show_a_list_of_blogs()
{
    var redisBlogs = redis.As<Blog>();
    var blogs = redisBlogs.GetAll();
    blogs.PrintDump();
}

只需要调用GetAll方法即可获取内存中的所有指定类型的对象。

输出结果为：

 
 
[
{

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
]
}
]

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[
    {
        
        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
        ]
    }
]

显示最近发表的文章和评论

实现如下:

 
 
 
 
 
 

C#

 
[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();

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

foreach (var newBlogPost in newIncomingBlogPosts)
{
//Prepend the new blog posts to the start of the 'RecentPosts' list
recentPosts.Prepend(newBlogPost);

//Prepend all the new blog post comments to the start of the 'RecentComments' list
newBlogPost.Comments.ForEach(recentComments.Prepend);
}

//Make this a Rolling list by only keep the latest 3 posts and comments
recentPosts.Trim(0, 2);
recentComments.Trim(0, 2);

//Print out the last 3 posts:
recentPosts.GetAll().PrintDump();
recentComments.GetAll().PrintDump();
}
}

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[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();
 
        //Let's get back an IList<BlogPost> wrapper around a Redis server-side List.
        var recentPosts = redisBlogPosts.Lists["urn:BlogPost:RecentPosts"];
        var recentComments = redisComments.Lists["urn:BlogPostComment:RecentComments"];
 
        foreach (var newBlogPost in newIncomingBlogPosts)
        {
            //Prepend the new blog posts to the start of the 'RecentPosts' list
            recentPosts.Prepend(newBlogPost);
 
            //Prepend all the new blog post comments to the start of the 'RecentComments' list
            newBlogPost.Comments.ForEach(recentComments.Prepend);
        }
 
        //Make this a Rolling list by only keep the latest 3 posts and comments
        recentPosts.Trim(0, 2);
        recentComments.Trim(0, 2);
 
        //Print out the last 3 posts:
        recentPosts.GetAll().PrintDump();
      recentComments.GetAll().PrintDump();
     }
}

方法中定义了两个key为urn:BlogPost:RecentPosts 和 urn:BlogPostComment:RecentComments的 List对象来保存最近发表的文章和评论：recentPosts.Prepend(newBlogPost)方法表示将新创建的文章插到recentPosts列表的最前面。

Trim方法表示仅保留n个在集合中。

显示博客的标签云

显示博客的标签云方法如下：

 
 
 
 
 
 

C#

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

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

//Show top 5 most popular tags with their scores
var tagCloud = redis.GetRangeWithScoresFromSortedSetDesc("urn:TagCloud", 0, 4);
tagCloud.PrintDump();
}

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[Test]
public void Show_a_TagCloud()
{
    //Get strongly-typed clients
    var redisBlogPosts = redis.As<BlogPost>();
    var newIncomingBlogPosts = redisBlogPosts.GetAll();
 
    foreach (var newBlogPost in newIncomingBlogPosts)
    {
        //For every tag in each new blog post, increment the number of times each Tag has occurred
        newBlogPost.Tags.ForEach(x =>
            redis.IncrementItemInSortedSet("urn:TagCloud", x, 1));
    }
 
    //Show top 5 most popular tags with their scores
    var tagCloud = redis.GetRangeWithScoresFromSortedSetDesc("urn:TagCloud", 0, 4);
    tagCloud.PrintDump();
}

显示标签云的实现，用到了redis中的SortedSet，IncrementItemInSortedSet表示如果有相同的话，值加一，GetRangeWithScoresFromSortedSetDesc方法，获取某一key的前5个对象。

显示所有的分类

显示所有的分类用到了Set对象。

 
 
 
 
 
 

C#

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

foreach (var blogPost in blogPosts)
{
blogPost.Categories.ForEach(x =>
redis.AddItemToSet("urn:Categories", x));
}

var uniqueCategories = redis.GetAllItemsFromSet("urn:Categories");
uniqueCategories.PrintDump();
}

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[Test]
public void Show_all_Categories()
{
    var redisBlogPosts = redis.As<BlogPost>();
    var blogPosts = redisBlogPosts.GetAll();
 
    foreach (var blogPost in blogPosts)
    {
        blogPost.Categories.ForEach(x =>
                redis.AddItemToSet("urn:Categories", x));
    }
 
    var uniqueCategories = redis.GetAllItemsFromSet("urn:Categories");
    uniqueCategories.PrintDump();
}

显示文章以及其评论

实现如下:

 
 
 
 
 
 

C#

 
[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();
}

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[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();
}

只需要把postId传进去就可以通过GetById的方法获取内存中的对象.

添加评论

首先根据PostId获取BlogPost，然后在Comment属性中添加一个BlogPostComment对象，然后在保存改BlogPost.

 
 
 
 
 
 

C#

 
[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);

var refreshBlogPost = redisBlogPosts.GetById(postId.ToString());
refreshBlogPost.PrintDump();
}

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[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);
 
    var refreshBlogPost = redisBlogPosts.GetById(postId.ToString());
    refreshBlogPost.PrintDump();
}

显示分类以及分类对应的文章

 
 
 
 
 
 

C#

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

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

//Retrieve all the post ids for the category you want to view
var documentDbPostIds = redis.GetAllItemsFromSet("urn:Category:DocumentDB");

//Make a batch call to retrieve all the posts containing the matching ids
//(i.e. the DocumentDB Category posts)
var documentDbPosts = redisBlogPosts.GetByIds(documentDbPostIds);

documentDbPosts.PrintDump();
}

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[Test]
public void Show_all_Posts_for_the_DocumentDB_Category()
{
    var redisBlogPosts = redis.As<BlogPost>();
    var newIncomingBlogPosts = redisBlogPosts.GetAll();
 
    foreach (var newBlogPost in newIncomingBlogPosts)
    {
        //For each post add it's Id into each of it's 'Cateogry > Posts' index
        newBlogPost.Categories.ForEach(x =>
                redis.AddItemToSet("urn:Category:" + x, newBlogPost.Id.ToString()));
    }
 
    //Retrieve all the post ids for the category you want to view
    var documentDbPostIds = redis.GetAllItemsFromSet("urn:Category:DocumentDB");
 
    //Make a batch call to retrieve all the posts containing the matching ids
    //(i.e. the DocumentDB Category posts)
    var documentDbPosts = redisBlogPosts.GetByIds(documentDbPostIds);
 
    documentDbPosts.PrintDump();
}

这里首先把所有的文章按照标签新建Set，把相同的分类的文章放到一个Set中，最后根据key即可查找到相应的集合。

总结

本文利用一个简单的博客系统，简要介绍了如何利用Redis存储和获取复杂的数据。由于本文主要为了演示如何与Redis进行交互，所以实体设计的很简陋，没有按照DDD的思想进行设计，在某些设计方面没有遵循前文浅谈依赖注入中使用的原理和方法，后面会写文章对该系统进行重构以使之更加完善。

希望本文对您了解如何利用Redis存储复杂对象有所帮助。

参考资料

  1. Designing NoSql Database
  2. Migrations Using Schemaless NoSql
  3. That No SQL Thing: The relational modeling anti pattern in document databases

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