In this section, we will explore how to use MongoDB with C#. We will cover the following topics:
- Setting up the environment
- Connecting to MongoDB
- Performing CRUD operations
- Practical exercises
- Setting up the Environment
Before we start coding, we need to set up our development environment.
Prerequisites
- Visual Studio or Visual Studio Code
- .NET SDK
- MongoDB server (local or cloud-based like MongoDB Atlas)
Installing the MongoDB Driver for C#
To interact with MongoDB from a C# application, we need to install the MongoDB.Driver package. You can do this using the NuGet Package Manager in Visual Studio or by running the following command in the terminal:
- Connecting to MongoDB
Let's start by creating a simple C# console application that connects to a MongoDB database.
Example Code
using MongoDB.Bson;
using MongoDB.Driver;
using System;
namespace MongoDBWithCSharp
{
class Program
{
static void Main(string[] args)
{
// Connection string to MongoDB server
var connectionString = "mongodb://localhost:27017";
// Create a MongoClient object
var client = new MongoClient(connectionString);
// Get the database (create if not exists)
var database = client.GetDatabase("testdb");
// Get the collection (create if not exists)
var collection = database.GetCollection<BsonDocument>("testcollection");
Console.WriteLine("Connected to MongoDB!");
}
}
}Explanation
- MongoClient: This class is used to connect to a MongoDB server.
- GetDatabase: This method retrieves a database. If the database does not exist, it will be created.
- GetCollection: This method retrieves a collection from the database. If the collection does not exist, it will be created.
- Performing CRUD Operations
Creating Documents
To insert a document into a MongoDB collection, we use the InsertOne method.
Example Code
var document = new BsonDocument
{
{ "name", "John Doe" },
{ "age", 30 },
{ "email", "[email protected]" }
};
collection.InsertOne(document);
Console.WriteLine("Document inserted!");Reading Documents
To read documents from a MongoDB collection, we use the Find method.
Example Code
var filter = Builders<BsonDocument>.Filter.Eq("name", "John Doe");
var result = collection.Find(filter).FirstOrDefault();
if (result != null)
{
Console.WriteLine(result.ToString());
}
else
{
Console.WriteLine("No document found!");
}Updating Documents
To update a document, we use the UpdateOne method.
Example Code
var filter = Builders<BsonDocument>.Filter.Eq("name", "John Doe");
var update = Builders<BsonDocument>.Update.Set("age", 31);
collection.UpdateOne(filter, update);
Console.WriteLine("Document updated!");Deleting Documents
To delete a document, we use the DeleteOne method.
Example Code
var filter = Builders<BsonDocument>.Filter.Eq("name", "John Doe");
collection.DeleteOne(filter);
Console.WriteLine("Document deleted!");
- Practical Exercises
Exercise 1: Insert Multiple Documents
Task: Write a program to insert multiple documents into a MongoDB collection.
Solution:
var documents = new List<BsonDocument>
{
new BsonDocument { { "name", "Alice" }, { "age", 25 }, { "email", "[email protected]" } },
new BsonDocument { { "name", "Bob" }, { "age", 28 }, { "email", "[email protected]" } }
};
collection.InsertMany(documents);
Console.WriteLine("Multiple documents inserted!");Exercise 2: Find Documents with a Specific Condition
Task: Write a program to find all documents where the age is greater than 25.
Solution:
var filter = Builders<BsonDocument>.Filter.Gt("age", 25);
var results = collection.Find(filter).ToList();
foreach (var doc in results)
{
Console.WriteLine(doc.ToString());
}Exercise 3: Update Multiple Documents
Task: Write a program to update the email of all documents where the name is "Alice".
Solution:
var filter = Builders<BsonDocument>.Filter.Eq("name", "Alice");
var update = Builders<BsonDocument>.Update.Set("email", "[email protected]");
collection.UpdateMany(filter, update);
Console.WriteLine("Multiple documents updated!");Exercise 4: Delete Documents with a Specific Condition
Task: Write a program to delete all documents where the age is less than 30.
Solution:
var filter = Builders<BsonDocument>.Filter.Lt("age", 30);
collection.DeleteMany(filter);
Console.WriteLine("Multiple documents deleted!");Conclusion
In this section, we learned how to set up a C# environment to work with MongoDB, connect to a MongoDB database, and perform CRUD operations. We also provided practical exercises to reinforce the concepts. In the next module, we will explore real-world applications of MongoDB with C#.