MongoDB學(xué)習(xí)筆記(四) 用MongoDB的文檔結(jié)構(gòu)描述數(shù)據(jù)關(guān)系
MongoDB的集合（collection）可以看做關(guān)系型數(shù)據(jù)庫(kù)的表，文檔對(duì)象（document）可以看做關(guān)系型數(shù)據(jù)庫(kù)的一條記錄。但兩者并不完全對(duì)等。表的結(jié)構(gòu)是固定的，MongoDB集合并沒(méi)有這個(gè)約束；另外，存入集合的文檔對(duì)象甚至可以嵌入子文檔，或者“子集合”。他們最終都可以用類似于BJSON的格式描述。我們今天就來(lái)分析MongoDB這一特性帶來(lái)的獨(dú)特?cái)?shù)據(jù)管理方式。我們還是以samus驅(qū)動(dòng)為例來(lái)分析，samus驅(qū)動(dòng)支持兩種方式訪問(wèn)數(shù)據(jù)庫(kù)，基本方式和linq方式，基本方式在上篇以介紹過(guò)，linq方式我不想單獨(dú)講解應(yīng)用實(shí)例，這篇我會(huì)用兩種方式來(lái)對(duì)比介紹。
一、包含子文檔的集合操作
有這么一個(gè)應(yīng)用場(chǎng)景，某網(wǎng)站提供會(huì)員登錄的功能，用戶需要注冊(cè)賬號(hào)才能享受會(huì)員服務(wù)，但是注冊(cè)者可能會(huì)因?yàn)橛脩糍Y料表單輸入項(xiàng)過(guò)大而放棄填寫(xiě)，因此用戶信息分為主要資料和詳細(xì)資料兩項(xiàng)，初次注冊(cè)只需要填寫(xiě)主要資料就行了。我們打算把詳細(xì)信息設(shè)計(jì)為子文檔存儲(chǔ)。
1) linq方式實(shí)現(xiàn)
1. 新建數(shù)據(jù)描述類，描述用戶信息
- /// <summary>
- /// 用戶主要資料
- /// </summary>
- public class UserInfo
- {
- public string UserId { get; set; }
- public string UserName { get; set; }
- public string PassWord { get; set; }
- public Detail Detail { get; set; }
- }
- /// <summary>
- /// 用戶詳細(xì)資料
- /// </summary>
- public class Detail
- {
- public string Address { get; set; }
- public int Age { get; set; }
- public string Email { get; set; }
- }
2. 我們要新建一個(gè)用戶業(yè)務(wù)操作類“UserBLL”。這個(gè)時(shí)候要讓驅(qū)動(dòng)知道UserInfo類描述了“用戶資料”的字段信息，在GetMongo()方法實(shí)現(xiàn)了配置步驟，UserBLL完整代碼如下：
- public class UserBLL
- {
- public string connectionString = "mongodb://localhost";
- public string databaseName = "myDatabase";
- private Mongo mongo;
- private MongoDatabase mongoDatabase;
- //注意這里泛型類型為“UserInfo”
- private MongoCollection<UserInfo> mongoCollection;
- public UserBLL()
- {
- mongo = GetMongo();
- mongoDatabase = mongo.GetDatabase(databaseName) as MongoDatabase;
- mongoCollection = mongoDatabase.GetCollection<UserInfo>() as MongoCollection<UserInfo>;
- mongo.Connect();
- }
- ~UserBLL()
- {
- mongo.Disconnect();
- }
- /// <summary>
- /// 配置Mongo,將類UserInfo映射到集合
- /// </summary>
- private Mongo GetMongo()
- {
- var config = new MongoConfigurationBuilder();
- config.Mapping(mapping =>
- {
- mapping.DefaultProfile(profile =>
- {
- profile.SubClassesAre(t => t.IsSubclassOf(typeof(UserInfo)));
- });
- mapping.Map<UserInfo>();
- });
- config.ConnectionString(connectionString);
- return new Mongo(config.BuildConfiguration());
- }
- }
3. 接著，在“UserBLL”類中定義一個(gè)方法“InsertSomeData()”來(lái)插入一些數(shù)據(jù)：
- /// <summary>
- /// 插入一些數(shù)據(jù)
- /// </summary>
- public void InsertSomeData()
- {
- UserInfo userInfo1 = new UserInfo()
- {
- UserId = "1001",
- UserName = "張三",
- PassWord = "123456"
- };
- mongoCollection.Save(userInfo1);
- UserInfo userInfo2 = new UserInfo()
- {
- UserId = "1002",
- UserName = "李四",
- PassWord = "123456",
- Detail = new Detail()
- {
- Address = "湖北",
- Age = 20,
- Email = "lisi@163.com"
- }
- };
- mongoCollection.Save(userInfo2);
- UserInfo userInfo3 = new UserInfo()
- {
- UserId = "1003",
- UserName = "王五",
- PassWord = "123456",
- Detail = new Detail()
- {
- Address = "廣東",
- Age = 20,
- Email = "wangwu@163.com"
- }
- };
- mongoCollection.Save(userInfo3);
- UserInfo userInfo4 = new UserInfo()
- {
- UserId = "1004",
- UserName = "趙六",
- PassWord = "123456",
- Detail = new Detail()
- {
- Address = "湖北"
- }
- };
- mongoCollection.Save(userInfo4);
- }
4. 定義一個(gè)查找數(shù)據(jù)的方法“Select”，它將查找用戶詳細(xì)信息中，地址在湖北的全部用戶：
- <summary>
- /// 查詢?cè)敿?xì)資料地址為湖北的用戶信息
- /// </summary>
- public List<UserInfo> Select()
- {
- return mongoCollection.Linq().Where(x => x.Detail.Address == "湖北").ToList();
- }
5. 還定義一個(gè)刪除數(shù)據(jù)的方法，將刪除集合全部數(shù)據(jù)：
- /// <summary>
- /// 刪除全部用戶信息
- /// </summary>
- public void DeleteAll()
- {
- mongoCollection.Remove(x => true);
- }
6. 在Main方法中添加如下代碼：
- static void Main(string[] args)
- {
- UserBLL userBll = new UserBLL();
- userBll.InsertSomeData();
- var users = userBll.Select();
- foreach (var user in users)
- {
- Console.WriteLine(user.UserName + "是湖北人");
- };
- userBll.DeleteAll();
- }
7. ***執(zhí)行程序，打印如下信息：
李四是湖北人
趙六是湖北人
1) 普通實(shí)現(xiàn)
普通方式實(shí)現(xiàn)不想多講，直接貼代碼，看看與linq方式有什么區(qū)別：
- class Program
- {
- static void Main(string[] args)
- {
- UserBLL userBll = new UserBLL();
- userBll.InsertSomeData();
- var users = userBll.Select();
- foreach (var user in users)
- {
- Console.WriteLine(user["UserName"].ToString() + "是湖北人");
- };
- userBll.DeleteAll();
- Console.ReadLine();
- }
- }
- public class UserBLL
- {
- public string connectionString = "mongodb://localhost";
- public string databaseName = "myDatabase";
- public string collectionName = "UserInfo";
- private Mongo mongo;
- private MongoDatabase mongoDatabase;
- private MongoCollection<Document> mongoCollection;
- public UserBLL()
- {
- mongo = new Mongo(connectionString);
- mongoDatabase = mongo.GetDatabase(databaseName) as MongoDatabase;
- mongoCollection = mongoDatabase.GetCollection<Document>(collectionName) as MongoCollection<Document>;
- mongo.Connect();
- }
- ~UserBLL()
- {
- mongo.Disconnect();
- }
- /// <summary>
- /// 插入一些數(shù)據(jù)
- /// </summary>
- public void InsertSomeData()
- {
- Document userInfo1 = new Document();
- userInfo1["UserId"] = "1001";
- userInfo1["UserName"] = "張三";
- userInfo1["PassWord"] = "123456";
- mongoCollection.Save(userInfo1);
- Document userInfo2 = new Document();
- userInfo2["UserId"] = "1002";
- userInfo2["UserName"] = "李四";
- userInfo2["PassWord"] = "123456";
- //子文檔
- var userInfo2Detail = new Document();
- userInfo2Detail["Address"] = "湖北";
- userInfo2Detail["Age"] = 20;
- userInfo2Detail["Email"] = "lisi@163.com";
- userInfo2["Detail"] = userInfo2Detail;
- mongoCollection.Save(userInfo2);
- Document userInfo3 = new Document();
- userInfo3["UserId"] = "1003";
- userInfo3["UserName"] = "王五";
- userInfo3["PassWord"] = "123456";
- var userInfo3Detail = new Document();
- userInfo3Detail["Address"] = "廣東";
- userInfo3Detail["Age"] = 20;
- userInfo3Detail["Email"] = "wangwu@163.com";
- userInfo3["Detail"] = userInfo3Detail;
- mongoCollection.Save(userInfo3);
- Document userInfo4 = new Document();
- userInfo4["UserId"] = "1004";
- userInfo4["UserName"] = "趙六";
- userInfo4["PassWord"] = "123456";
- var userInfo4Detail = new Document();
- userInfo4Detail["Address"] = "湖北";
- userInfo4["Detail"] = userInfo4Detail;
- mongoCollection.Save(userInfo4);
- }
- /// <summary>
- /// 查詢?cè)敿?xì)資料地址為湖北的用戶信息
- /// </summary>
- public IEnumerable<Document> Select()
- {
- return mongoCollection.Find(new Document { { "Detail.Address", "湖北" } }).Documents;
- }
- /// <summary>
- /// 刪除全部用戶信息
- /// </summary>
- public void DeleteAll()
- {
- mongoCollection.Remove(new Document { });
- }
- }
***，我們通過(guò)這段代碼輸出全部用戶資料信息的BJSON格式：
- /// <summary>
- /// 打印數(shù)據(jù)BJSON
- /// </summary>
- public void PrintBJSON()
- {
- string BJSON = string.Empty;
- foreach (var documet in mongoCollection.FindAll().Documents)
- {
- BJSON += documet.ToString();
- }
- Console.WriteLine(BJSON);
- }
- 結(jié)果如下：
- { "UserId": "1001", "UserName": "張三", "PassWord": "123456", "_id": "4d80ec1ab8a4731338000001" }
- { "UserId": "1002", "UserName": "李四", "PassWord": "123456", "Detail": { "Address": "湖北", "Age": 20, "Email": "lisi@163.com" }, "_id": "4d80ec1ab8a4731338000002" }
- { "UserId": "1003", "UserName": "王五", "PassWord": "123456", "Detail": { "Address": "廣東", "Age": 20, "Email": "wangwu@163.com" }, "_id": "4d80ec1ab8a4731338000003" }
- { "UserId": "1004", "UserName": "趙六", "PassWord": "123456", "Detail": { "Address": "湖北" }, "_id": "4d80ec1ab8a4731338000004" }
#p#
二、包含“子集合”的集合操作
同樣舉個(gè)例子：有一個(gè)學(xué)校人事管理系統(tǒng)要統(tǒng)計(jì)班級(jí)和學(xué)生的信息，現(xiàn)在定義了一個(gè)“班級(jí)集合”，這個(gè)集合里面的學(xué)生字段是一個(gè)“學(xué)生集合”，包含了本班全部學(xué)生。
1) linq方式實(shí)現(xiàn)
基礎(chǔ)配置我就不多說(shuō)了，數(shù)據(jù)類定義如下：
- /// <summary>
- /// 班級(jí)信息
- /// </summary>
- public class ClassInfo
- {
- public string ClassName { get; set; }
- public List<Student> Students { get; set; }
- }
- /// <summary>
- /// 學(xué)生信息
- /// </summary>
- public class Student
- {
- public string Name { get; set; }
- public int Age { get; set; }
- }
查詢叫“張三”的學(xué)生在哪個(gè)班級(jí)，以及他的詳細(xì)信息：
(這里其實(shí)是ToList后在內(nèi)存中查的,linq方式直接查詢好像驅(qū)動(dòng)不支持。)
- public List<ClassInfo> Select()
- {
- return mongoCollection.Linq().ToList().Where(x => x.Students.Exists(s => s.Name == "張三")).ToList();
- }
1) 普通實(shí)現(xiàn)
查詢叫“張三”的學(xué)生在哪個(gè)班級(jí)，以及他的詳細(xì)信息：
- public List<Document> Select()
- {
- var mongocollection = mongoDatabase.GetCollection("ClassInfo");
- return mongocollection.Find(new Document { { "Students.Name", "張三" } }).Documents.ToList();
- }
打印數(shù)據(jù)的BJSON：
- { "_id": "4d814bae5c5f000000005f63", "ClassName": "1001", "Students": [ { "Name": "張三", "Age": 10 }, { "Name": "李四", "Age": 0 } ] }
- { "_id": "4d814bae5c5f000000005f64", "ClassName": "1002", "Students": [ ] }
- { "_id": "4d814bae5c5f000000005f65", "ClassName": "1003", "Students": [ { "Name": "王五", "Age": 11 }, { "Name": "趙六", "Age": 9 } ] }
三、小結(jié)
通過(guò)本節(jié)例子我們發(fā)現(xiàn)，MongoDB有它獨(dú)特的文檔結(jié)構(gòu)可以描述數(shù)據(jù)對(duì)象之間的一些關(guān)系特征。它雖然沒(méi)有關(guān)系型數(shù)據(jù)庫(kù)多表符合查詢那樣強(qiáng)大的表間查詢方式，但也可以通過(guò)文檔結(jié)構(gòu)描述更靈活的關(guān)系特性，可以這么說(shuō)，關(guān)系型數(shù)據(jù)庫(kù)能做的，MongoDB基本上也可以做到。甚至有些關(guān)系數(shù)據(jù)庫(kù)不容易做到的，MongoDB也可以輕松做到，比如，描述數(shù)據(jù)類的繼承關(guān)系等
原文鏈接：http://www.cnblogs.com/lipan/archive/2011/03/17/1986616.html
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