MongoDB map-reduce-Mongo shell and C # (lower)

Following the previous article, this article is mainly implemented by the C # version of Mongo map-Reduce. If you are not familiar with the C # driver, it doesn't matter. The MongoDB official website has a good getting started article, you will soon learn how to write the Mongo program in C #, instead of entering commands on the console every day. Getting Started
With the CSHARP driver.

Let's go back to the subject,

II. C # version:

1. construct object class record. CS:

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace TestApp{    /// <summary>    /// The Class of Record    /// </summary>    public class Record    {        /// <summary>        /// The Customer Id        /// </summary>        public int cusid { get; set; }                /// <summary>        /// The Price        /// </summary>        public int price { get; set; }    }}

2. Compile mongodbhelper. CS: Some Common Operations

using System;using System.Collections.Generic;using System.Linq;using System.Text;using MongoDB.Driver;namespace TestApp{    /// <summary>    /// The Class of MongoDBHelper: common operation for MongoDB    /// </summary>    public class MongoDBHelper    {        /// <summary>        /// Get the specific db instance        /// </summary>        /// <param name="connectionString">The connect string</param>        /// <param name="dbName">DB name</param>        /// <returns>The DB instance</returns>        public static MongoDatabase GetDatabase(string connectionString, string dbName)        {            var client = new MongoClient(connectionString);            var server = client.GetServer();            MongoDatabase database = server.GetDatabase(dbName);            return database;        }    }}

3. Implement the map-Reduce program:

    class Program    {        /// <summary>        /// Insert test data to records collection in db        /// </summary>        /// <param name="records">The records instance</param>        static void InsertTestDataToRecords(MongoCollection<Record> records)        {            records.Insert<Record>(new Record() { cusid = 1, price = 15 });            records.Insert<Record>(new Record() { cusid = 2, price = 30 });            records.Insert<Record>(new Record() { cusid = 2, price = 45 });            records.Insert<Record>(new Record() { cusid = 3, price = 45 });            records.Insert<Record>(new Record() { cusid = 4, price = 5 });            records.Insert<Record>(new Record() { cusid = 5, price = 65 });            records.Insert<Record>(new Record() { cusid = 1, price = 10 });            records.Insert<Record>(new Record() { cusid = 1, price = 30 });            records.Insert<Record>(new Record() { cusid = 5, price = 30 });            records.Insert<Record>(new Record() { cusid = 4, price = 100 });            records.Insert<Record>(new Record() { cusid = 3, price = 10 });        }        static void Main(string[] args)        {            #region Test MongoDB Map-Reduce            // Connection string format: mongodb://[username:password@][host][:port]/[database]            var connectionString = "mongodb://Kevin:123456@localhost:27017/admin";            string dbName = "admin";            var db = MongoDBHelper.GetDatabase(connectionString, dbName);            var records = db.GetCollection<Record>("records");            InsertTestDataToRecords(records);            // Write map and reduce function            string mapFunction = @"function(){                                        emit(this.cusid, this.price);                                    };";            string reduceFunction = @"function(cusid, prices){                                        var total = 0;                                        total = Array.sum(prices);                                        return { sum: total };                                    };";            // Execute map-reduce method            var cusid_prices_results = records.MapReduce(mapFunction, reduceFunction);            // Print results            Console.WriteLine("Print the results of executing MapReduce method:\r\n");            foreach (var item in cusid_prices_results.GetResults())            {                Console.WriteLine(item.ToString());            }            Console.ReadKey();            #endregion        }    }

Execution result:

The result is the same as that of Mongo shell in the previous article. So far, the map-reduce application of MongoDB is here, I will continue to update more features and knowledge about MongoDB later. Thank you!