第二节 为什么用MongoDB及.NET开发入门

using System;
using System.Configuration;
using System.Linq;
using MongoDB;
using MongoDB.Configuration;
using MongoDB.Linq;

namespace Simple
{
    /// <summary>
    ///   Illustrates some simple operations on the database.
    ///   Creating a database connection.
    ///   Remove some documents.
    ///   Insert some documents
    ///   Find one document
    ///   Find several documents and iterate through them.
    /// </summary>
    internal class MainClass
    {
        private IMongoCollection<Document> categories;
        private Mongo mongo;
        private IMongoDatabase simple;

        private class MyClass
        {
            public string Name { get; set; }
            public  int Corners { get; set; }
        }

        private class SubClass : MyClass
        {
            public double Ratio { get; set; }
        }

        public static void Main(string[] args)
        {
            #region 以下为被屏蔽源码部分，我们先从SetUp方法开始
            //var config = new MongoConfigurationBuilder();
            //// COMMENT OUT FROM HERE
            //config.Mapping(mapping =>
            //{
            //    mapping.DefaultProfile(profile =>
            //    {
            //        profile.SubClassesAre(t => t.IsSubclassOf(typeof(MyClass)));
            //    });
            //    mapping.Map<MyClass>();
            //    mapping.Map<SubClass>();
            //});
            //// TO HERE

            //config.ConnectionString("Server=127.0.0.1");

            //using (Mongo mongo = new Mongo(config.BuildConfiguration()))
            //{
            //    mongo.Connect();
            //    try
            //    {
            //        var db = mongo.GetDatabase("TestDb");
            //        var collection = db.GetCollection<MyClass>();

            //        MyClass square = new MyClass()
            //        {
            //            Corners = 4,
            //            Name = "Square"
            //        };

            //        MyClass circle = new MyClass()
            //        {
            //            Corners = 0,
            //            Name = "Circle"
            //        };

            //        SubClass sub = new SubClass()
            //        {
            //            Name = "SubClass",
            //            Corners = 6,
            //            Ratio = 3.43
            //        };

            //        collection.Save(square);
            //        collection.Save(circle);
            //        collection.Save(sub);

            //        var superclass = (from item in db.GetCollection<MyClass>("MyClass").Linq()
            //                    where item.Corners > 1
            //                    select item.Corners).ToList();

            //        var subclass = (from item in db.GetCollection<SubClass>("MyClass").Linq()
            //                        where item.Ratio > 1
            //                        select item.Corners).ToList();

            //        Console.WriteLine("Count by LINQ on typed collection: {0}", collection.Linq().Count(x => x.Corners > 1));
            //        Console.WriteLine("Count by LINQ on typed collection2: {0}", db.GetCollection<SubClass>().Linq().Count(x => x.Corners > 1));
            //        //Console.WriteLine("Count by LINQ on typed collection3: {0}", db.GetCollection<SubClass>().Count(new { Corners = Op.GreaterThan(1) }));
            //        Console.WriteLine("Count on typed collection: {0}", collection.Count(new { Corners = Op.GreaterThan(1) }));

            //        var coll = db.GetCollection("MyClass");
            //        var count = coll.Count(new Document("Corners", Op.GreaterThan(1)));
            //        Console.WriteLine("Count: {0}", count);
            //        Console.ReadKey();
            //    }
            //    finally
            //    {
            //        mongo.Disconnect();
            //    }
            //}
            #endregion

            var main = new MainClass();
            main.Setup();
            main.Run();

            Console.ReadLine();
        }

        /// <summary>
        ///   Setup the collection and insert some data into it.
        /// </summary>
        public void Setup()
        {
            //从配置文件读取连接字符串 IP+端口
            var connstr = ConfigurationManager.AppSettings["simple"];
            if(String.IsNullOrEmpty(connstr))
                throw new ArgumentNullException("Connection string not found.");
            //创建Mongo数据服务及连接
            mongo = new Mongo(connstr);
            mongo.Connect();
            
            //获取数据库实例（如果该实例不存，就会自动创建simple实例)
            simple = mongo["simple"];
            //获取表名（如果该表名不存在，就会自动创建categories表名)
            categories = simple.GetCollection<Document>("categories");
            //添加记录前清除所有记录
            Clean();

            var names = new[] {"Bluez", "Jazz", "Classical", "Rock", "Oldies", "Heavy Metal"};
            //循环插入记录 doucment会自动生成键值_id，id的编码体现了数据的插入顺序
            foreach(var name in names)
                categories.Insert(new Document {{"name", name}});
        }

        public void Clean()
        {
            //删除document name 为Jazz的记录
            categories.Remove(new Document {{"name", "Jazz"}}); //remove documents with the name Jazz.
            //删除所有记录集
            categories.Remove(new Document()); //remove everything from the categories collection.
        }

        public void Run()
        {
            //查找单条记录 参数类型为Document
            var category = categories.FindOne(new Document {{"name", "Bluez"}});
            Console.WriteLine("The id findOne" + category["_id"]);
            
            //更新1 用键值ID读取对象，并更新字段值，保存
            var selector = new Document {{"_id", category["_id"]}};
            category["name"] = "Bluess";
            //The following will do the same thing.
            categories.Save(category);
            Console.WriteLine("Category after one update " + categories.FindOne(selector));
            //更新2 Update参数1去更新参数2并保存
            category["name"] = "Blues";
            categories.Update(category, selector);
            Console.WriteLine("Category after two updates " + categories.FindOne(selector));

            //Find it by _id that has been converted to a string now.
            var id = (category["_id"]).ToString();
            //注意： 这里id.ToString()与id.ToOid() （为什么类扩展这个方法，我也没明白，是不是id!=24 位会出现转义字符要替换掉)
            Console.WriteLine(string.Format("Found by string id[{0}] converted back to Oid[{1}]",id.ToString(),id.ToOid()));
            Console.WriteLine(categories.FindOne(new Document {{"_id", id.ToOid()}}));

            //Find(new Document()) is equivalent to FindAll();
            //Specifying the cursor in a using block will close it on the server if we decide not
            //to iterate through the whole thing.
            Console.WriteLine("输出所有对象.........");
            using(var all = categories.Find(new Document()))
            {
                foreach(var doc in all.Documents)
                    Console.WriteLine(doc.ToString());
            }

            mongo.Disconnect();
        }
    }
}

//类扩展ToOid方法到string中
public static class OidExtensions
{
    public static Oid ToOid(this string str)
    {
        if(str.Length == 24)
            return new Oid(str);

        return new Oid(str.Replace("\"", ""));
    }
}