MongoDB C# Driver

https://www.mongodb.com/docs/drivers/csharp/current/
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The official MongoDB .NET/C# Driver enables developers to work with MongoDB databases in C#...
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### Run the application with dotnet run

Source: https://www.mongodb.com/docs/drivers/csharp/current/get-started/

Run this command in your shell to start the application. The output includes details of the retrieved movie document.

```bash
dotnet run csharp-quickstart.csproj
```

--------------------------------

### POCO query output

Source: https://www.mongodb.com/docs/drivers/csharp/current/get-started/

Example output from the POCO approach. Shows the Title, Plot, and Genres properties of the retrieved movie.

```text
Title: Back to the Future
Plot: A young man is accidentally sent 30 years into the past...
Genres: Adventure, Comedy, Sci-Fi
```

--------------------------------

### BsonDocument query output

Source: https://www.mongodb.com/docs/drivers/csharp/current/get-started/

Example output from the BsonDocument approach. Shows the retrieved movie document with fields like _id, plot, genres, and title.

```json
{
  _id: ...,
  plot: 'A young man is accidentally sent 30 years into the past...',
  genres: [ 'Adventure', 'Comedy', 'Sci-Fi' ],
  ...
  title: 'Back to the Future',
  ...
}
```

--------------------------------

### Create a project directory and initialize a console application

Source: https://www.mongodb.com/docs/drivers/csharp/current/get-started/

Run these shell commands to create a directory named csharp-quickstart and initialize a new .NET console application with dotnet new console.

```shell
mkdir csharp-quickstart
cd csharp-quickstart
dotnet new console
```

--------------------------------

### Asynchronous BulkWriteAsync() with BulkWriteModel

Source: https://www.mongodb.com/docs/drivers/csharp/current/crud/bulk-write/

Same bulk write setup as the synchronous example but calls the asynchronous BulkWriteAsync() method. Use await inside an async method. Output is a BulkWriteResult object printed to the console.

```csharp
var client = new MongoClient("mongodb://localhost:27017");
var restaurantNamespace = "sample_restaurants.restaurants";
var movieNamespace = "sample_mflix.movies";
var bulkWriteModels = new[]
{
    new BulkWriteInsertOneModel<BsonDocument>(
        restaurantNamespace,
        new BsonDocument{
            { "name", "Mongo's Deli" },
            { "cuisine", "Sandwiches" },
            { "borough", "Manhattan" },
            { "restaurant_id", "1234" }
        }
    ),
    new BulkWriteInsertOneModel<BsonDocument>(
        movieNamespace,
        new BsonDocument{
            { "name", "Sarah's Secret" },
            { "year", 1988 }
        }
    ),
    new BulkWriteUpdateManyModel<BsonDocument>(
        restaurantNamespace,
        Builders<BsonDocument>.Filter.Eq("name", "Mongo's Deli"),
        Builders<BsonDocument>.Update.Set("cuisine", "Sandwiches and Salads")
    ),
    new BulkWriteDeleteOneModel<BsonDocument>(
        movieNamespace,
        Builders<BsonDocument>.Filter.Eq("title", "House")
    )
};
var result = await client.BulkWriteAsync(bulkWriteModels);
Console.WriteLine(result);
```

--------------------------------

### Run the Application with dotnet run

Source: https://www.mongodb.com/docs/drivers/csharp/current/crud/restful-api-tutorial/

Execute this command to start the application. After it starts, open the configured localhost URL (e.g., http://localhost:5000/swagger) to access the Swagger UI.

```bash
dotnet run
```

--------------------------------

### Output of Find() and FindAsync() examples

Source: https://www.mongodb.com/docs/drivers/csharp/current/crud/gridfs/

Sample output from the synchronous and asynchronous find examples, showing JSON documents for two files with fields like _id, length, chunkSize, uploadDate, and filename.

```json
{ "_id" : { "$oid" : "..." }, "length" : 13, "chunkSize" : 261120, "uploadDate" :
{ "$date" : ... }, "filename" : "new_file" }
{ "_id" : { "$oid" : "..." }, "length" : 50, "chunkSize" : 1048576, "uploadDate" :
{ "$date" : ... }, "filename" : "my_file" }
```

--------------------------------

### Output of combined Limit, Sort, and Skip example

Source: https://www.mongodb.com/docs/drivers/csharp/current/crud/query/specify-documents/

The output displayed after running the example, showing the first 10 documents returned after skipping the first 10 sorted results.

```text
Acqua
Acqua Restaurant
Acqua Santa
Acquista Trattoria
Acquolina Catering
Adriatic Restaurant Pizzeria Bar
Adrienne'S Pizza Bar
Ai Fiori
Aita Restaurant
Al Di La
```

--------------------------------

### Sample restaurant documents

Source: https://www.mongodb.com/docs/drivers/csharp/current/reference/quick-reference/

Example documents from the restaurants collection, showing borough and name fields.

```json
[
  { borough : "Brooklyn", name : "Philadelphia Grille Express" }
  { borough : "Manhattan", name : "Isle Of Capri Restaurant" }
  { borough : "Manhattan", name : "Marchis Restaurant" }
  ...
]
```

--------------------------------

### Results of $search example

Source: https://www.mongodb.com/docs/drivers/csharp/current/aggregation/linq/

Example output documents from the $search example, truncated. Shows matching restaurant documents with Name and Cuisine fields.

```json
// Results Truncated
{ "Name" : "Mexico Lindo Y ! Q Rico! Deli", "Cuisine" : "Mexican" }
{ "Name" : "Cold Cut City Bunny Deli 2", "Cuisine" : "American" }
{ "Name" : "Blue Moon Chicken Deli & Pizza Corp", "Cuisine" : "Other" }
{ "Name" : "Little Michaels Deli And Sald Bar", "Cuisine" : "Delicatessen" }
{ "Name" : "La Esperanza Mexican Deli Grocery & Vegetables", "Cuisine" : "Mexican" }
{ "Name" : "El Sol De Mexico Deli Grocery", "Cuisine" : "Mexican" }
{ "Name" : "C & C Deli Coffee Shop & Pastry", "Cuisine" : "Delicatessen" }
{ "Name" : "Jennis Deli And Grill And Grocery", "Cuisine" : "Spanish" }
{ "Name" : "La Nueva Estrella Pizza And Deli Grocery", "Cuisine" : "Spanish" }
{ "Name" : "Blue Cafe/3 In 1 Deli Restaurant", "Cuisine" : "American" }
```

--------------------------------

### Query with BsonDocument in Program.cs

Source: https://www.mongodb.com/docs/drivers/csharp/current/get-started/

Use this code in Program.cs to query the sample_mflix movies collection using a BsonDocument filter. It requires the MONGODB_URI environment variable to be set, otherwise it prints a message and exits. The output is printed as indented JSON.

```csharp
using MongoDB.Bson;
using MongoDB.Bson.IO;
using MongoDB.Driver;
var connectionString = Environment.GetEnvironmentVariable("MONGODB_URI");
if (connectionString == null)
{
    Console.WriteLine("You must set your 'MONGODB_URI' environment variable. To learn how to set it, see https://www.mongodb.com/docs/drivers/csharp/current/get-started/create-connection-string");
    Environment.Exit(0);
}
var client = new MongoClient(connectionString);
var collection = client.GetDatabase("sample_mflix").GetCollection<BsonDocument>("movies");
var filter = Builders<BsonDocument>.Filter.Eq("title", "Back to the Future");
var document = collection.Find(filter).First();
Console.WriteLine(document.ToJson(new JsonWriterSettings { Indent = true }));
```

--------------------------------

### $sample result documents

Source: https://www.mongodb.com/docs/drivers/csharp/current/aggregation/linq/

Example output documents from the $sample stage, showing the random sample.

```json
// Results Truncated
{ "name" : "Von Dolhens", "cuisine" : "Ice Cream, Gelato, Yogurt, Ices" }
{ "name" : "New York Mercantile Exchange", "cuisine" : "American" }
{ "name" : "Michaelangelo's Restaurant", "cuisine" : "Italian" }
{ "name" : "Charlie Palmer Steak", "cuisine" : "American" }
```

--------------------------------

### Implement GET endpoint in PlaylistController.cs

Source: https://www.mongodb.com/docs/drivers/csharp/current/crud/restful-api-tutorial/

Updates the Get method to call GetAsync and return the list of playlists.

```csharp
[HttpGet]
public async Task<List<Playlist>> Get() {
  return await _mongoDBService.GetAsync();
}
```

--------------------------------

### dbStats Command Output

Source: https://www.mongodb.com/docs/drivers/csharp/current/run-command/

Example output from the dbStats command, showing storage statistics for the sample_restaurants database.

```json
{ "db" : "sample_restaurants", "collections" : 2, "views" : 0, "objects" :
NumberLong(25438), "avgObjSize" : 548.95172576460413, "dataSize" : NumberLong(13964234),
"storageSize" : NumberLong(8056832), "totalFreeStorageSize" : NumberLong(0),
"numExtents" : NumberLong(0), "indexes" : 2, "indexSize" : NumberLong(1044480),
"indexFreeStorageSize" : NumberLong(0), "fileSize" : NumberLong(0), "nsSizeMB" : 0, "ok" : 1 }
```

--------------------------------

### Output of $skip example (truncated)

Source: https://www.mongodb.com/docs/drivers/csharp/current/aggregation/linq/

The result of the $skip example, showing the documents returned after skipping the first two matching restaurants. The output is truncated.

```json
// Results Truncated
{ "name" : "Marchis Restaurant", "cuisine" : "Italian" }
{ "name" : "Crystal Room", "cuisine" : "Italian" }
{ "name" : "Forlinis Restaurant", "cuisine" : "Italian" }
...
```

--------------------------------

### $sort Example Results

Source: https://www.mongodb.com/docs/drivers/csharp/current/aggregation/linq/

Sample subset of documents returned by the $sort examples, sorted by name and restaurant_id. Results are truncated.

```json
// Results Truncated
...
{ "_id" : ObjectId(...), "name" : "Aba Turkish Restaurant", "restaurant_id" : "41548686", "cuisine" : "Turkish", "address" : {...}, "borough" : "Manhattan", "grades" : [...] }
{ "_id" : ObjectId(...), "name" : "Abace Sushi", "restaurant_id" : "50006214", "cuisine" : "Japanese", "address" : { ... }, "borough" : "Manhattan", "grades" : [...] }
{ "_id" : ObjectId(...), "name" : "Abacky Potluck", "restaurant_id" : "50011222", "cuisine" : "Asian", "address" : { ... }, "borough" : "Manhattan", "grades" : [...] }
{ "_id" : ObjectId(...), "name" : "Abaleh", "restaurant_id" : "50009096", "cuisine" : "Mediterranean", "address" : { ... }, "borough" : "Manhattan", "grades" : [...] }
...
```

--------------------------------

### SearchAfter Example

Source: https://www.mongodb.com/docs/drivers/csharp/current/atlas-search/

This example demonstrates how to paginate MongoDB Search results using the SearchAfter property of SearchOptions. It defines a projection with MetaSearchSequenceToken, creates SearchOptions with index and sort, runs a base search, and then uses the PaginationToken to set SearchAfter for the next search.

```csharp
var projection = Builders<Movie>.Projection
    .Include(x => x.Title)
    .MetaSearchSequenceToken(x => x.PaginationToken);
var searchDefinition = Builders<Movie>.Search.Text(m => m.Plot, "time travel");
var searchOptions = new SearchOptions<Movie>
{ IndexName = "default", Sort = Builders<Movie>.Sort.Ascending(m => m.Id) };
// Runs the base search operation
var baseSearchResults = moviesCollection.Aggregate()
    .Search(searchDefinition, searchOptions)
    .Project<Movie>(projection)
    .ToList();
if (baseSearchResults.Count == 0)
    return baseSearchResults;
// Sets the starting point for the next search
searchOptions.SearchAfter = baseSearchResults[0].PaginationToken;
var result = moviesCollection.Aggregate()
    .Search(searchDefinition, searchOptions)
    .Project<Movie>(projection)
    .ToList();
```

--------------------------------

### Install MongoDB.AspNetCore.OData NuGet package

Source: https://www.mongodb.com/docs/drivers/csharp/current/integrations/odata/

Run this .NET CLI command to install the MongoDB.AspNetCore.OData package, which enables OData integration with MongoDB.

```bash
dotnet add package MongoDB.AspNetCore.OData
```

--------------------------------

### Change Stream Output with Post-Image

Source: https://www.mongodb.com/docs/drivers/csharp/current/logging-and-monitoring/change-streams/

Example output from the preceding change stream example after updating a document with a "name" value of "Blarney Castle". Shows the full document (post-image) included in the change event.

```text
{ "_id" : ObjectId("..."), "name" : "Blarney Castle", "restaurant_id" : "40366356",
"cuisine" : "Traditional Irish", "address" : { "building" : "202-24", "coord" : [-73.925044200000002, 40.5595462],
"street" : "Rockaway Point Boulevard", "zipcode" : "11697" }, "borough" : "Queens", "grades" : [...] }
```

--------------------------------

### $group Example Results

Source: https://www.mongodb.com/docs/drivers/csharp/current/aggregation/linq/

Sample output from the $group examples, showing documents with 'cuisine' and 'count' fields. Results are truncated and may appear in a different order when you run the query.

```json
// Results Truncated
{ "cuisine" : "Caribbean", "count" : 657 }
{ "cuisine" : "Café/Coffee/Tea", "count" : 1214 }
{ "cuisine" : "Iranian", "count" : 2 }
{ "cuisine" : "Nuts/Confectionary", "count" : 6 }
{ "cuisine" : "Middle Eastern", "count" : 168 }
...
```

--------------------------------

### Example GUID

Source: https://www.mongodb.com/docs/drivers/csharp/current/serialization/guids/

A GUID is a 16-byte integer used as a unique ID for a MongoDB document. This example shows the standard string representation of a GUID.

```text
00112233-4455-6677-8899-aabbccddeeff
```

--------------------------------

### Get Reference to the guitars Collection

Source: https://www.mongodb.com/docs/drivers/csharp/current/crud/query/query-filter/

Creates a MongoClient and obtains a reference to the 'guitars' collection in the 'example' database. Required to run the code examples on this page.

```C#
var client = new MongoClient("localhost://27017");
var guitarCollection = client.GetDatabase("example").GetCollection<Guitar>("guitars");
```

--------------------------------

### Create a new .NET Core web API project

Source: https://www.mongodb.com/docs/drivers/csharp/current/crud/restful-api-tutorial/

Run these commands in your terminal to create a new .NET Core project named MongoExample that uses a web application template, then navigate into the project directory.

```bash
dotnet new webapi -o MongoExample
cd MongoExample
```

--------------------------------

### Specify GUID representation with BsonGuidRepresentation attribute

Source: https://www.mongodb.com/docs/drivers/csharp/current/serialization/guids/

Add the BsonGuidRepresentation attribute to a GUID property to specify its representation when automapping C# classes. The attribute accepts a value from the GuidRepresentation enum; this example sets Standard (subtype 4) for the G property.

```csharp
public class Widget
{
    public int Id { get; set; }
   [BsonGuidRepresentation(GuidRepresentation.Standard)]
   public Guid G { get; set; }
}
```

--------------------------------

### Register ID generator for all Guid IDs

Source: https://www.mongodb.com/docs/drivers/csharp/current/serialization/poco/

Use BsonSerializer.RegisterIdGenerator to specify a single IIdGenerator for all Id properties of a certain data type. This example instructs the driver to use CombGuidGenerator for all Guid IDs.

```csharp
BsonSerializer.RegisterIdGenerator(
  typeof(Guid),
  CombGuidGenerator.Instance
);
```

--------------------------------

### Guid.Empty Auto ID Generation Behavior

Source: https://www.mongodb.com/docs/drivers/csharp/current/serialization/guids/

When serializing Guid.Empty values, the .NET/C# Driver treats them as unset IDs and generates a new GUID on insert. This example demonstrates that behavior.

```csharp
var doc = new MyDocument { Name = "Test" }; // Id will default to Guid.Empty
collection.InsertOne(doc); // doc.Id will now contain a generated GUID, not Guid.Empty
```

--------------------------------

### Load PEM certificate with X509Certificate2.CreateFromPem()

Source: https://www.mongodb.com/docs/drivers/csharp/current/security/authentication/x509/

Provides a .pem format certificate directly by reading the certificate and key files, importing the encrypted private key, and creating an X509Certificate2 instance with the private key. Replace the password placeholder with your actual password.

```csharp
var certPem = File.ReadAllText("client.crt");
var keyPem = File.ReadAllText("client.key");
var rsa = RSA.Create();
rsa.ImportFromEncryptedPem(keyPem, "<password>");
var cert = X509Certificate2.CreateFromPem(certPem);
var clientCertificate = cert.CopyWithPrivateKey(rsa);
```

--------------------------------

### Example BSON document

Source: https://www.mongodb.com/docs/drivers/csharp/current/document-formats/bson/

Sample BSON document used by the guide's code samples, showing nested documents, arrays, and string fields.

```json
{
    "address" : {
        "street" : "Pizza St",
        "zipcode" : "10003"
    },
    "coord" : [-73.982419, 41.579505]
    "cuisine" : "Pizza",
    "name" : "Mongo's Pizza"
}
```

--------------------------------

### Set MONGODB_URI environment variable (PowerShell)

Source: https://www.mongodb.com/docs/drivers/csharp/current/get-started/

Use this command instead if you are using Microsoft PowerShell. Replace <your MongoDB URI> with the connection string saved earlier.

```powershell
set MONGODB_URI="<your MongoDB URI>"
```

--------------------------------

### Create a GridFSBucket instance

Source: https://www.mongodb.com/docs/drivers/csharp/current/crud/gridfs/

Creates a new GridFSBucket for the 'db' database. The constructor accesses an existing bucket or creates a new one if it does not exist.

```csharp
var client = new MongoClient("<connection string>");
var database = client.GetDatabase("db");
// Creates a GridFS bucket or references an existing one
var bucket = new GridFSBucket(database);
```

--------------------------------

### Sample Data for the guitars Collection

Source: https://www.mongodb.com/docs/drivers/csharp/current/crud/query/query-filter/

Documents used by the examples in this guide, stored in the 'guitars' collection. The documents use camel-case field names and include optional 'rating' fields.

```JSON
{ "_id": 1, "make": "Fender", "models": ["Stratocaster", "Telecaster"], "establishedYear": 1946, "rating": 9 }
{ "_id": 2, "make": "Gibson", "models": ["Les Paul", "SG", "Explorer"], "establishedYear": 1902, "rating": 8 }
{ "_id": 3, "make": "PRS", "models": ["Silver Sky", "SE", "Custom"], "establishedYear": 1985, "rating": 9 }
{ "_id": 4, "make": "Kiesel", "models": ["Ares", "Vader", "Solo"], "establishedYear": 2015 }
{ "_id": 5, "make": "Ibanez", "models": ["RG", "AZ"], "establishedYear": 1957, "rating": 7 }
{ "_id": 6, "make": "Strandberg", "models": ["Boden", "Salen"], "establishedYear": 1982 }
```

--------------------------------

### Run the hello command synchronously with RunCommand

Source: https://www.mongodb.com/docs/drivers/csharp/current/run-command/

Creates a BsonDocument specifying the hello command and passes it to the RunCommand method on a database instance. The response is deserialized into a BsonDocument. Use this when you need to run a database command synchronously.

```csharp
var command = new BsonDocument("hello", 1);
var result = database.RunCommand<BsonDocument>(command);
```

--------------------------------

### Use MongoUrlBuilder to create MongoUrl

Source: https://www.mongodb.com/docs/drivers/csharp/current/connect/connection-options/

Create a MongoUrlBuilder instance, set configuration properties, call ToMongoUrl() to get a MongoUrl, and pass it to the MongoClient constructor. This example sets ServerMonitoringMode to Stream.

```csharp
const string connectionUri = "mongodb+srv://localhost:27017/?connectTimeoutMS=60000&tls=true";
var builder = new MongoUrlBuilder(connectionUri)
{
    ServerMonitoringMode = MongoDB.Driver.Core.Servers.ServerMonitoringMode.Stream
};
var url = builder.ToMongoUrl();
var client = new MongoClient(url);
```

--------------------------------

### Configure X.509 authentication via connection string

Source: https://www.mongodb.com/docs/drivers/csharp/current/security/authentication/x509/

Sets up X.509 authentication using a connection string with authSource=$external and authMechanism=MONGODB-X509, then configures TLS and client certificates. Replace the hostname, port, and certificate path/password placeholders.

```csharp
var connectionString = "mongodb[+srv]://<hostname>[:<port>]/?authSource=$external&authMechanism=MONGODB-X509";
var settings = MongoClientSettings.FromConnectionString(connectionString);
settings.UseTls = true;
settings.SslSettings = new SslSettings
{
   ClientCertificates = new List<X509Certificate>()
   {
       new X509Certificate2("<path to X.509 certificate>", "<X.509 certificate password>")
   }
};
```

--------------------------------

### JSON response from /odata/Restaurants endpoint

Source: https://www.mongodb.com/docs/drivers/csharp/current/integrations/odata/

Example JSON response returned by the Get endpoint when querying /odata/Restaurants. It contains a list of restaurants with fields such as Name, RestaurantId, Cuisine, Borough, Id, Address, and Grades.

```json
{
  "@odata.context": "http://localhost:5183/odata/$metadata#Restaurants",
  "value": [
    {
      "Name": "Glorious Food",
      "RestaurantId": "40361521",
      "Cuisine": "American",
      "Borough": "Manhattan",
      "Id": "...",
      "Address": {
        "Building": "522",
        "Coordinates": [-73.95171, 40.767461],
        "Street": "East   74 Street",
        "ZipCode": "10021"
      },
      "Grades": [
        ...
      ]
    },
    ...
    ]
}
```

--------------------------------

### Run the hello command asynchronously with RunCommandAsync

Source: https://www.mongodb.com/docs/drivers/csharp/current/run-command/

Creates a BsonDocument specifying the hello command and passes it to the RunCommandAsync method on a database instance. The response is deserialized into a BsonDocument. Use this when you need to run a database command asynchronously.

```csharp
var command = new BsonDocument("hello", 1);
var result = await database.RunCommandAsync<BsonDocument>(command);
```

--------------------------------

### PushEach() asynchronous update to add multiple values to array

Source: https://www.mongodb.com/docs/drivers/csharp/current/crud/update-one/arrays/

Same as the synchronous PushEach() example but uses UpdateOneAsync() for asynchronous execution. Adds two GradeEntry objects to the start of the Grades array and sorts by Score descending.

```C#
var filter = Builders<Restaurant>.Filter.Eq("name", "Downtown Deli");
var newGrades = new List<GradeEntry>
{
    new GradeEntry { Date = DateTime.Now, Grade = "A", Score = 95 },
    new GradeEntry { Date = DateTime.Now, Grade = "B+", Score = 89,}
};
var scoreSort = Builders<GradeEntry>.Sort.Descending(g => g.Score);
var update = Builders<Restaurant>.Update.PushEach(
    "Grades",
    newGrades,
    position: 0,
    sort: scoreSort);
var result = await _restaurantsCollection.UpdateOneAsync(filter, update);
return result;
```

--------------------------------

### Create BulkWriteInsertOneModel instances for client bulk write

Source: https://www.mongodb.com/docs/drivers/csharp/current/crud/bulk-write/

Creates two BulkWriteInsertOneModel<BsonDocument> instances to insert documents into the sample_restaurants.restaurants and sample_mflix.movies collections. Each constructor takes a collection namespace string and a BsonDocument to insert. Requires MongoDB Server 8.0 or later.

```csharp
var restaurantToInsert = new BulkWriteInsertOneModel<BsonDocument>(
    "sample_restaurants.restaurants",
    new BsonDocument{
        { "name", "Mongo's Deli" },
        { "cuisine", "Sandwiches" },
        { "borough", "Manhattan" },
        { "restaurant_id", "1234" }
    }
);
var movieToInsert = new BulkWriteInsertOneModel<BsonDocument>(
    "sample_mflix.movies",
    new BsonDocument{
        { "title", "Silly Days" },
        { "year", 2022 }
    }
);
```

--------------------------------

### Set MONGODB_URI environment variable (bash)

Source: https://www.mongodb.com/docs/drivers/csharp/current/get-started/

Run in your shell to save your MongoDB connection string to an environment variable. Replace <your MongoDB URI> with the connection string saved earlier. Storing credentials in an environment variable is safer than hardcoding them in source code.

```bash
export MONGODB_URI="<your MongoDB URI>"
```

--------------------------------

### Create PlaylistController.cs with CRUD endpoints

Source: https://www.mongodb.com/docs/drivers/csharp/current/crud/restful-api-tutorial/

Defines the PlaylistController with GET, POST, PUT, and DELETE endpoints. The constructor injects the MongoDBService singleton. Endpoint methods are placeholders to be implemented in subsequent steps. No data validation is applied to HTTP requests in this example project.

```csharp
using System;
using Microsoft.AspNetCore.Mvc;
using MongoExample.Services;
using MongoExample.Models;
namespace MongoExample.Controllers; 
[Controller]
[Route("api/[controller]")]
public class PlaylistController: Controller {
    
    private readonly MongoDBService _mongoDBService;
    public PlaylistController(MongoDBService mongoDBService) {
        _mongoDBService = mongoDBService;
    }
    [HttpGet]
    public async Task<List<Playlist>> Get() {}
    [HttpPost]
    public async Task<IActionResult> Post([FromBody] Playlist playlist) {}
    [HttpPut("{id}")]
    public async Task<IActionResult> AddToPlaylist(string id, [FromBody] string movieId) {}
    [HttpDelete("{id}")]
    public async Task<IActionResult> Delete(string id) {}
}
```

--------------------------------

### Connect service to application in Program.cs

Source: https://www.mongodb.com/docs/drivers/csharp/current/crud/restful-api-tutorial/

Adds using directives and configures MongoDB settings from appsettings.json. Registers MongoDBService as a singleton.

```csharp
using MongoExample.Models;
using MongoExample.Services;
var builder = WebApplication.CreateBuilder(args);
builder.Services.Configure<MongoDBSettings>(builder.Configuration.GetSection("MongoDB"));
builder.Services.AddSingleton<MongoDBService>();
```

--------------------------------

### Construct a legacy GUID with BsonBinaryData and GuidRepresentation.CSharpLegacy

Source: https://www.mongodb.com/docs/drivers/csharp/current/serialization/guids/

Use the BsonBinaryData constructor with GuidRepresentation.CSharpLegacy to create a legacy (subtype 3) GUID for use in a query filter. This is required because legacy GUIDs cannot be constructed with the default representation.

```csharp
var guid = new Guid("00112233-4455-6677-8899-aabbccddeeff");
var legacyGuid = new BsonBinaryData(guid, GuidRepresentation.CSharpLegacy);
var filter = new BsonDocument("legacyGuidField", legacyGuid);
```

--------------------------------

### $project result document

Source: https://www.mongodb.com/docs/drivers/csharp/current/aggregation/linq/

Example output document from the $project stage, showing the projected fields.

```json
{ "name" : "The Movable Feast", "address" : { "building" : "284", "coord" : [-73.982923900000003, 40.6580753], "street" : "Prospect Park West", "zipcode" : "11215" } }
```

--------------------------------

### Serialize GUID IDs with GuidSerializer

Source: https://www.mongodb.com/docs/drivers/csharp/current/serialization/class-mapping/

Specifies the Standard GUID representation when registering a class map for GUID IDs.

```csharp
BsonClassMap.RegisterClassMap<Person>(classMap =>
{
     classMap.AutoMap();
     classMap.IdMemberMap.SetSerializer(new GuidSerializer(GuidRepresentation.Standard));
});
```

--------------------------------

### Update a Document with UpdateOne()

Source: https://www.mongodb.com/docs/drivers/csharp/current/reference/quick-reference/

Synchronous update of a single document using Builders<Restaurant>.Filter.Eq and Builders<Restaurant>.Update.Set.

```csharp
var filter = Builders<Restaurant>.Filter
  .Eq(restaurant => restaurant.Name, "Bagels N Buns");
var update = Builders<Restaurant>.Update
  .Set(restaurant => restaurant.Name, "2 Bagels 2 Buns");
var result = _restaurantsCollection.UpdateOne(filter, update);
```

--------------------------------

### Query with POCO Movie class in Program.cs

Source: https://www.mongodb.com/docs/drivers/csharp/current/get-started/

Use this code in Program.cs to query the sample_mflix movies collection using a POCO (Movie class). It requires the MONGODB_URI environment variable to be set, otherwise it prints a message and exits. The output prints the Title, Plot, and Genres properties. The Movie class uses Bson attributes to map to the collection fields.

```csharp
using MongoDB.Bson;
using MongoDB.Bson.Serialization.Attributes;
using MongoDB.Driver;
var connectionString = Environment.GetEnvironmentVariable("MONGODB_URI");
if (connectionString == null)
{
    Console.WriteLine("You must set your 'MONGODB_URI' environment variable. To learn how to set it, see https://www.mongodb.com/docs/drivers/csharp/current/get-started/create-connection-string");
    Environment.Exit(0);
}
var client = new MongoClient(connectionString);
var collection = client.GetDatabase("sample_mflix").GetCollection<Movie>("movies");
var filter = Builders<Movie>.Filter.Eq(m => m.Title, "Back to the Future");
var movie = collection.Find(filter).First();
Console.WriteLine($"Title: {movie.Title}");
Console.WriteLine($"Plot: {movie.Plot}");
Console.WriteLine($"Genres: {string.Join(", ", movie.Genres ?? [])}");
[BsonIgnoreExtraElements]
public class Movie
{
    [BsonId]
    public ObjectId Id { get; set; }
    [BsonElement("title")]
    public string? Title { get; set; }
    [BsonElement("plot")]
    public string? Plot { get; set; }
    [BsonElement("genres")]
    public List<string>? Genres { get; set; }
}
```

--------------------------------

### Review class for $lookup example

Source: https://www.mongodb.com/docs/drivers/csharp/current/aggregation/linq/

Models documents in the reviews collection with BsonElement attributes for restaurant_name and review_text.

```csharp
public class Review
{
    public ObjectId Id { get; set; }
    [BsonElement("restaurant_name")]
    public string RestaurantName { get; set; }
    public string Reviewer { get; set; }
    [BsonElement("review_text")]
    public string ReviewText { get; set; }
}
```

--------------------------------

### Change a BSON Document with BsonDocument Methods

Source: https://www.mongodb.com/docs/drivers/csharp/current/document-formats/bson/

Shows how to modify a BsonDocument by adding a new field with Add(), removing a field with Remove(), and updating a field value with Set(). The example starts with a BsonDocument containing address, coord, cuisine, and name fields, then adds restaurant_id, removes cuisine, and changes name to "Mongo's Pizza Palace".

```csharp
var newRestaurant = new BsonDocument
{
    { "address", new BsonDocument
        {
            { "street", "Pizza St" },
            { "zipcode", "10003" }
        }
    },
    { "coord", new BsonArray
        {-73.982419, 41.579505 }
    },
    { "cuisine", "Pizza" },
    { "name", "Mongo's Pizza"}
};
newRestaurant.Add(new BsonElement("restaurant_id", "12345"));
newRestaurant.Remove("cuisine");
newRestaurant.Set("name", "Mongo's Pizza Palace");
```

--------------------------------

### Insert a Document with InsertOne()

Source: https://www.mongodb.com/docs/drivers/csharp/current/reference/quick-reference/

Synchronous insert of a single Restaurant document using InsertOne().

```csharp
var insertResult = _restaurantsCollection.InsertOne(new Restaurant { Name = "Mongo's Pizza" });
```

--------------------------------

### Synchronous Bulk Write with ClientBulkWriteOptions

Source: https://www.mongodb.com/docs/drivers/csharp/current/crud/bulk-write/

Configures a bulk write operation with IsOrdered=false, WriteConcern.Unacknowledged, and VerboseResult=true, then calls the synchronous BulkWrite() method. The delete model targets the 'sample_restaurants.restaurants' collection.

```csharp
var client = new MongoClient("mongodb://localhost:27017");
var deleteOneModel = new BulkWriteDeleteOneModel<BsonDocument>(
    "sample_restaurants.restaurants",
    Builders<BsonDocument>.Filter.Eq("restaurant_id", "5678")
);
var clientBulkWriteOptions = new ClientBulkWriteOptions
{
    IsOrdered = false,
    WriteConcern = WriteConcern.Unacknowledged,
    VerboseResult = true
};
var result = client.BulkWrite(deleteOneModel, clientBulkWriteOptions);
```

--------------------------------

### Search with wildcard path using Wildcard() method

Source: https://www.mongodb.com/docs/drivers/csharp/current/atlas-search/

Use the Wildcard() method to specify a search path with wildcard characters. The '*' matches any sequence of characters. MongoDB Server searches only indexed fields whose names match the pattern and whose data type matches the search operator. This example searches all fields starting with 'p' for documents containing 'secret agent'.

```csharp
var result = moviesCollection.Aggregate()
    .Search(Builders<Movie>.Search.Text(
        Builders<Movie>.SearchPath.Wildcard("p*"), "secret agent"))
    .ToList();
```

--------------------------------

### Create ObjectSerializer with GuidRepresentation.Standard

Source: https://www.mongodb.com/docs/drivers/csharp/current/serialization/guids/

Creates an ObjectSerializer configured for GUID representation subtype 4 (Standard). Use this when serializing hierarchical objects to subdocuments to ensure GUIDs are handled correctly. The objectDiscriminatorConvention is looked up for the object type.

```csharp
var objectDiscriminatorConvention = BsonSerializer.LookupDiscriminatorConvention(typeof(object));
var objectSerializer = new ObjectSerializer(objectDiscriminatorConvention, GuidRepresentation.Standard);
```

--------------------------------

### Connect with authSource in connection string

Source: https://www.mongodb.com/docs/drivers/csharp/current/connect/connection-troubleshooting/

C# example using a connection URI with the authSource option set to 'users' to specify a non-default authentication database. Creates a MongoClient with the URI.

```csharp
using MongoDB.Driver;
// Connection URI
const string connectionUri = "mongodb://<db_username>:<db_password>@<hostname>:<port>/?authSource=users";
// Create a new client and connect to the server
var client = new MongoClient(connectionUri);
```

--------------------------------

### TakeWhile() result arrays

Source: https://www.mongodb.com/docs/drivers/csharp/current/aggregation/linq/

Example output arrays from the TakeWhile() example.

```json
[92, 97]
[100, 95, 91]
```

--------------------------------

### Asynchronous Bulk Write with ClientBulkWriteOptions

Source: https://www.mongodb.com/docs/drivers/csharp/current/crud/bulk-write/

Configures a bulk write operation with IsOrdered=false, WriteConcern.Unacknowledged, and VerboseResult=true, then calls the asynchronous BulkWriteAsync() method. The delete model targets the 'sample_restaurants.restaurants' collection.

```csharp
var client = new MongoClient("mongodb://localhost:27017");
var deleteOneModel = new BulkWriteDeleteOneModel<BsonDocument>(
    "sample_restaurants.restaurants",
    Builders<BsonDocument>.Filter.Eq("restaurant_id", "5678")
);
var clientBulkWriteOptions = new ClientBulkWriteOptions
{
    IsOrdered = false,
    WriteConcern = WriteConcern.Unacknowledged,
    VerboseResult = true
};
var result = await client.BulkWriteAsync(deleteOneModel, clientBulkWriteOptions);
```

--------------------------------

### Driver Encodings of GUID to BsonBinaryData Subtype 3

Source: https://www.mongodb.com/docs/drivers/csharp/current/serialization/guids/

Different MongoDB drivers encode GUIDs with different byte orders when using BsonBinaryData subtype 3. The tabs show the encodings for the .NET/C# Driver, PyMongo, and Java Driver.

```text
33221100-5544-7766-8899-aabbccddeeff
```

```text
00112233-4455-6677-8899-aabbccddeeff
```

```text
77665544-3322-1100-ffee-ddccbbaa9988
```

--------------------------------

### Enable client-side projection with Project() aggregation stage

Source: https://www.mongodb.com/docs/drivers/csharp/current/reference/release-notes/

Configure AggregateOptions with ExpressionTranslationOptions to enable client-side projections for the Project() aggregation stage using the LINQ3 provider. Requires setting EnableClientSideProjections to true.

```csharp
// Enable client-side projection
var aggregateOptions = new AggregateOptions();
aggregateOptions.TranslationOptions = new ExpressionTranslationOptions
{
    EnableClientSideProjections = true
};
var aggregate = collection
    .Aggregate(aggregateOptions)
    .Project(doc => new { R = MyFunction(doc.Name) });
```

--------------------------------

### Register a global GuidSerializer

Source: https://www.mongodb.com/docs/drivers/csharp/current/serialization/guids/

Register a GuidSerializer globally early in your application (e.g., during bootstrapping) when most GUIDs use the same representation. If you don't register a global serializer, you must apply the BsonGuidRepresentation attribute to every serializable GUID property or the driver throws an exception.

```csharp
BsonSerializer.RegisterSerializer(new GuidSerializer(GuidRepresentation.Standard));
```

--------------------------------

### Create an index with Builders<Restaurant>.IndexKeys

Source: https://www.mongodb.com/docs/drivers/csharp/current/reference/quick-reference/

Creates an ascending index on the Cuisine field using the C# driver's IndexKeys builder and CreateOne method.

```csharp
var index = Builders<Restaurant>.IndexKeys
  .Ascending(restaurant => restaurant.Cuisine);
_restaurantsCollection.Indexes
  .CreateOne(new CreateIndexModel<Restaurant>(index));
```

--------------------------------

### Create BulkWriteReplaceOneModel instances for replace operations

Source: https://www.mongodb.com/docs/drivers/csharp/current/crud/bulk-write/

Creates two BulkWriteReplaceOneModel<BsonDocument> objects to replace documents in the sample_restaurants.restaurants and sample_mflix.movies collections. The constructor accepts a collection namespace, a query filter, and a replacement document.

```csharp
var restaurantReplacement = new BulkWriteReplaceOneModel<BsonDocument>(
    "sample_restaurants.restaurants",
    Builders<BsonDocument>.Filter.Eq("restaurant_id", "1234"),
    new BsonDocument{
        { "name", "Mongo's Pizza" },
        { "cuisine", "Pizza" },
        { "borough", "Brooklyn" },
        { "restaurant_id", "5678" }
    }
);
var movieReplacement = new BulkWriteReplaceOneModel<BsonDocument>(
    "sample_mflix.movies",
    Builders<BsonDocument>.Filter.Eq("title", "Insomnia"),
    new BsonDocument{
        { "name", "Loving Sylvie" },
        { "year", 1999 }
    }
);
```
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