Working with MongoDB Transactions with C# and the .NET Framework

1
using MongoDB.Bson;
2
using MongoDB.Bson.Serialization.Attributes;
3
using MongoDB.Driver;
4
using System;
5
using System.Threading.Tasks;
6
7
namespace MongoDBTransaction
8
{
9
    public static class Program
10
    {
11
        public class Product
12
        {
13
            [BsonId]
14
            public ObjectId Id { get; set; }
15
            [BsonElement("SKU")]
16
            public int SKU { get; set; }
17
            [BsonElement("Description")]
18
            public string Description { get; set; }
19
            [BsonElement("Price")]
20
            public Double Price { get; set; }
21
        }
22
23
        // replace with your connection string if it is different
24
        const string MongoDBConnectionString = "mongodb://localhost";
25
26
        public static async Task Main(string[] args)
27
        {
28
            if (!await UpdateProductsAsync()) { Environment.Exit(1); }
29
            Console.WriteLine("Finished updating the product collection");
30
            Console.ReadKey();
31
        }
32
33
        private static async Task<bool> UpdateProductsAsync()
34
        {
35
            // Create client connection to our MongoDB database
36
            var client = new MongoClient(MongoDBConnectionString);
37
38
            // Create the collection object that represents the "products" collection
39
            var database = client.GetDatabase("MongoDBStore");
40
            var products = database.GetCollection<Product>("products");
41
42
            // Clean up the collection if there is data in there
43
            await database.DropCollectionAsync("products");
44
45
            // collections can't be created inside a transaction so create it first
46
            await database.CreateCollectionAsync("products");
47
48
            // Create a session object that is used when leveraging transactions
49
            using (var session = await client.StartSessionAsync())
50
            {
51
                // Begin transaction
52
                session.StartTransaction();
53
54
                try
55
                {
56
                    // Create some sample data
57
                    var tv = new Product { Description = "Television",
58
                                    SKU = 4001,
59
                                    Price = 2000 };
60
                    var book = new Product { Description = "A funny book",
61
                                    SKU = 43221,
62
                                    Price = 19.99 };
63
                    var dogBowl = new Product { Description = "Bowl for Fido",
64
                                    SKU = 123,
65
                                    Price = 40.00 };
66
67
                    // Insert the sample data
68
                    await products.InsertOneAsync(session, tv);
69
                    await products.InsertOneAsync(session, book);
70
                    await products.InsertOneAsync(session, dogBowl);
71
72
                    var resultsBeforeUpdates = await products
73
                                    .Find<Product>(session, Builders<Product>.Filter.Empty)
74
                                    .ToListAsync();
75
                    Console.WriteLine("Original Prices:\n");
76
                    foreach (Product d in resultsBeforeUpdates)
77
                    {
78
                        Console.WriteLine(
79
                                    String.Format("Product Name: {0}\tPrice: {1:0.00}",
80
                                        d.Description, d.Price)
81
                        );
82
                    }
83
84
                    // Increase all the prices by 10% for all products
85
                    var update = new UpdateDefinitionBuilder<Product>()
86
                            .Mul<Double>(r => r.Price, 1.1);
87
                    await products.UpdateManyAsync(session,
88
                            Builders<Product>.Filter.Empty,
89
                            update); //,options);
90
91
                    // Made it here without error? Let's commit the transaction
92
                    await session.CommitTransactionAsync();
93
                }
94
                catch (Exception e)
95
                {
96
                    Console.WriteLine("Error writing to MongoDB: " + e.Message);
97
                    await session.AbortTransactionAsync();
98
                    return false;
99
                }
100
101
                // Let's print the new results to the console
102
                Console.WriteLine("\n\nNew Prices (10% increase):\n");
103
                var resultsAfterCommit = await products
104
                        .Find<Product>(session, Builders<Product>.Filter.Empty)
105
                        .ToListAsync();
106
                foreach (Product d in resultsAfterCommit)
107
                {
108
                    Console.WriteLine(
109
                        String.Format("Product Name: {0}\tPrice: {1:0.00}",
110
                                                    d.Description, d.Price)
111
                    );
112
                }
113
114
                return true;
115
            }
116
        }
117
    }
118
}