MongoDB C# Driver

https://www.mongodb.com/docs/drivers/csharp/
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The MongoDB C# Driver is an official NuGet package that enables C#/.NET developers to connect to and...
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### Document Insertion Examples

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

Examples showing the input documents and the resulting collection state based on ordered or unordered insert behavior.

```json
{ "_id" : 1, "name" : "Restaurant A" }
{ "_id" : 2, "name" : "Restaurant B" }
{ "_id" : 1, "name" : "Restaurant C" }
{ "_id" : 3, "name" : "Restaurant D" }
```

```json
{ "_id" : 1, "name" : "Restaurant A" }
{ "_id" : 2, "name" : "Restaurant B" }
```

```json
{ "_id" : 1, "name" : "Restaurant A" }
{ "_id" : 2, "name" : "Restaurant B" }
{ "_id" : 3, "name" : "Restaurant D" }
```

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

### Change Stream Output Example

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

Example output showing the full document structure returned by a change stream.

```sh
{ "_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" : [...] }
```

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

### Run Application Command

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

Command to start the .NET application.

```bash
dotnet run
```

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

### Example GUID Format

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

A standard 16-byte GUID representation.

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

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

### Run the Application

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

Command to start the ASP.NET Core application from the project root.

```shell
dotnet run ODataExample.csproj
```

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

### Application Startup Output

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

Example terminal output indicating the application is listening for requests.

```none
info: Microsoft.Hosting.Lifetime[14]
      Now listening on: http://localhost:5183
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
      Content root path: <Path to your project>
```

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

### Example BSON Document Structure

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

A representation of the BSON document structure used in the examples.

```none
{
    "address" : {
        "street" : "Pizza St",
        "zipcode" : "10003"
    },
    "coord" : [-73.982419, 41.579505]
    "cuisine" : "Pizza",
    "name" : "Mongo's Pizza"
}
```

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

### Print Output

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

Example of printing a collection to the console.

```csharp
Console.WriteLine(restaurants);
```

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

### Install NuGet Dependencies

Source: https://www.mongodb.com/docs/drivers/csharp-frameworks/ef-odata

Commands to add the MongoDB EF Core provider and OData support to the project.

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

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

### Initialize Collection Reference

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

Obtain a reference to the guitars collection to run the query filter examples.

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

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

### Install AWS Authentication Package

Source: https://www.mongodb.com/docs/drivers/csharp/current/security/authentication/aws-iam

Add the required NuGet package to your project using the .NET CLI.

```bash
dotnet add package MongoDB.Driver.Authentication.AWS
```

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

### Example $search Results

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

Sample JSON output returned from the $search aggregation query.

```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" }
```

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

### WithTransactionAsync()

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

Starts a transaction on the session and runs the provided callback.

```APIDOC
## WithTransactionAsync()

### Description
Starts a transaction on this session and runs the given callback. Exceptions within the callback must be rethrown.

### Parameters
- **callback** (Func<IClientSessionHandle, CancellationToken, Task<TResult>>) - The function to execute within the transaction.
- **TransactionOptions** (optional) - Configuration options for the transaction.
- **CancellationToken** (optional) - Token to cancel the operation.

### Return Type
- **Task<TResult>**
```

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

### StartTransaction()

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

Starts a new transaction on the session, optionally configured with TransactionOptions.

```APIDOC
## StartTransaction()

### Description
Starts a new transaction, configured with the given options, on this session. Throws an exception if there is already a transaction in progress for the session.

### Parameters
- **TransactionOptions** (optional) - Configuration options for the transaction.
```

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

### Install MongoDB Driver and OData Package

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

Use the .NET CLI to add the necessary NuGet packages to your project.

```shell
dotnet add package MongoDB.Driver
```

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

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

### Example Output

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

The JSON representation of a document returned by the query.

```json
{ "_id" : 4, "make" : "Kiesel", "models" : ["Ares", "Vader", "Solo"], "establishedYear" : 2015, "rating" : null }
```

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

### Install the MongoDB Driver

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

Adds the MongoDB.Driver NuGet package as a dependency to the current project.

```bash
dotnet add package MongoDB.Driver
```

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

### Run and Test OData Application

Source: https://www.mongodb.com/docs/drivers/csharp-frameworks/ef-odata

Commands to start the application and verify OData endpoints using curl.

```bash
dotnet run
```

```bash
info: Microsoft.Hosting.Lifetime[14]
      Now listening on: http://localhost:5236
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
```

```bash
curl 'http://localhost:5236/odata/Restaurants?$top=5'
```

```text
{"@odata.context":"http://localhost:5236/odata/$metadata#Restaurants",
"value":[
   {"Id":"...","Name":"Riviera Caterer","Cuisine":
   "American","Borough":"Brooklyn","RestaurantId":"40356018"},
   {"Id":"...","Name":"Wilken'S Fine Food","Cuisine":
   "Delicatessen","Borough":"Brooklyn","RestaurantId":"40356483"},
   {"Id":"...","Name":"Kosher Island","Cuisine":
   "Jewish/Kosher","Borough":"Staten Island","RestaurantId":"40356442"},
   {"Id":"...","Name":"Wendy'S","Cuisine":"Hamburgers",
   "Borough":"Brooklyn","RestaurantId":"30112340"},
   {"Id":"...","Name":"Morris Park Bake Shop","Cuisine":
   "Bakery","Borough":"Bronx","RestaurantId":"30075445"}
]}
```

```bash
curl 'http://localhost:5236/odata/GetRestaurantsByBorough(borough=%27Queens%27)?$top=5'
```

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

### Authenticate with GSSAPI

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

Basic setup for GSSAPI authentication using either a connection string or a credential object.

```csharp
var mongoClient = new MongoClient(
   "mongodb://<username>:<password>@<hostname>[:<port>]/?authMechanism=GSSAPI");
```

```csharp
var credential = MongoCredential.CreateGssapiCredential("<username>", "<password>");
var settings = MongoClientSettings.FromConnectionString("<connection string>");
settings.Credential = credential;
var mongoClient = new MongoClient(settings);
```

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

### Execute a Multi-Document Transaction in C#

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

Demonstrates starting a session, configuring transaction options, and committing inserts across multiple collections.

```csharp
var books = database.GetCollection<Book>("books");
var films = database.GetCollection<Film>("films");

// Begins transaction
using (var session = mongoClient.StartSession())
{
    // Configures transaction options
    var transactionOptions = new TransactionOptions(
        readConcern: ReadConcern.Majority,
        writeConcern: WriteConcern.WMajority
    );

    session.StartTransaction(transactionOptions);

    try
    {
        // Creates sample data
        var book = new Book
        {
            Title = "Beloved",
            Author = "Toni Morrison",
            InStock = true
        };

        var film = new Film
        {
            Title = "Star Wars",
            Director = "George Lucas",
            InStock = true
        };

        // Inserts sample data
        books.InsertOne(session, book);
        films.InsertOne(session, film);

        // Commits our transaction
        session.CommitTransaction();
    } 
    catch (Exception e)
    {
        Console.WriteLine("Error writing to MongoDB: " + e.Message);
        return;
    }

    // Prints a success message if no error thrown
    Console.WriteLine("Successfully committed transaction!");
}
```

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

### Sample Data JSON

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

The documents used in the guitars collection for the examples.

```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 }
```

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

### Configure Read Preference via Connection URI

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

Example of specifying read preference, max staleness, and tags in a connection string.

```text
readPreference=primaryPreferred
&maxStalenessSeconds=90
&readPreferenceTags=dc:ny,rack:1
```

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

### Sample Playlist JSON Data

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

Example JSON payload for creating a new playlist entry.

```json
{
   "username": "testuser",
   "items": [
      "1234",
      "5678"
   ]
}
```

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

### Implement GET endpoint logic

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

Updates the service to retrieve all documents and the controller to return them.

```csharp
public async Task<List<Playlist>> GetAsync() { 
  return await _playlistCollection.Find(new BsonDocument()).ToListAsync();
}
```

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

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

### Initialize .NET Project

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

Commands to create a new web API project and add the MongoDB driver dependency.

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

```bash
dotnet add package MongoDB.Driver
```

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

### Create ASP.NET Core Project

Source: https://www.mongodb.com/docs/drivers/csharp-frameworks/ef-odata

Commands to initialize a new Web API project via the .NET CLI.

```bash
dotnet new webapi -n RestaurantODataApi
cd RestaurantODataApi
```

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

### Create an ObjectSerializer for GUIDs

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

Construct an ObjectSerializer with a specific GUID representation, such as subtype 4.

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

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

### Driver-Specific GUID Encodings

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

Comparison of how different MongoDB drivers encode the same GUID to BsonBinaryData subtype 3.

```csharp
33221100-5544-7766-8899-aabbccddeeff
```

```python
00112233-4455-6677-8899-aabbccddeeff
```

```java
77665544-3322-1100-ffee-ddccbbaa9988
```

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

### Configure Guid ID Generation

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

Specify ID generators for Guid types, including the COMB algorithm or default generation.

```csharp
public class House
{
   [BsonId(IdGenerator = typeof(CombGuidGenerator))]
   public Guid Id { get; set; }
}
```

```csharp
public class House
{
   public Guid Id { get; set; }
}
```

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

### Configure GUID ID Serialization

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

Specify the GUID representation for ID fields using a GuidSerializer within a class map.

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

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

### Configure GUID representation with attributes

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

Apply the BsonGuidRepresentation attribute to a class property to define its specific GUID representation during automapping.

```csharp
public class Widget
{
    public int Id { get; set; }

   [BsonGuidRepresentation(GuidRepresentation.Standard)]
   public Guid G { get; set; }
}
```

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

### Construct a legacy GUID for query filters

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

Use the BsonBinaryData constructor with GuidRepresentation.CSharpLegacy to explicitly create a subtype 3 GUID.

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

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

### Initialize a .NET Console Project

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

Creates a new directory and initializes a console application using the .NET CLI.

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

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

### Configure GUID serialization in code

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

Use the GuidSerializer class for manual serialization or register it globally to handle GUIDs throughout the application.

```text
var guidSerializer = new GuidSerializer(GuidRepresentation.Standard);
```

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

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

### Execute a Database Command

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

Run the 'hello' command to retrieve server information using either synchronous or asynchronous methods.

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

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

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

### Run the .NET Application

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

Execute the application using the .NET CLI.

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

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

### Find Operation Output

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

Example output from the find operation.

```text
Pizza Town
Victoria Pizza
...
```

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

### Create a session with MongoClient

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

Initializes a new session using the StartSession method. Reuse the client instance for multiple sessions rather than creating new clients.

```csharp
var client = new MongoClient("mongodb://localhost:27017");
var session = client.StartSession();
```

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

### Create a MongoClient instance

Source: https://www.mongodb.com/docs/drivers/csharp/current/connect/mongoclient

Initialize a new MongoClient by passing a connection URI string to the constructor.

```csharp
const string uri = "mongodb://localhost:27017/";
var client = new MongoClient(uri);
```

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

### Configure Authentication via Connection String

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

Set up X.509 authentication by specifying the authSource and authMechanism in the connection string.

```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>")
   }
};
```

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

### Proximity Query Results

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

Example JSON output for a proximity query.

```json
{ "_id" : ObjectId("59a47287cfa9a3a73e51e8e2"), "theaterId" : 1908 }
{ "_id" : ObjectId("59a47286cfa9a3a73e51e838"), "theaterId" : 1448 }
```

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

### Sample documents with LINQ

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

Use the Sample method on an aggregation pipeline to retrieve a random set of documents.

```csharp
var query = queryableCollection
    .Aggregate()
    .Sample(4)
    .ToList();
```

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

### WithTransaction()

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

Starts a transaction on the session and executes a provided callback function.

```APIDOC
## WithTransaction()

### Description
Starts a transaction on this session and runs the given callback. Exceptions within the callback must be rethrown to avoid infinite loops.

### Parameters
- **callback** (Func<IClientSessionHandle, CancellationToken, Task<TResult>>) - The function to execute within the transaction.
- **TransactionOptions** (optional) - Configuration options for the transaction.
- **CancellationToken** (required) - Token to monitor for cancellation requests.

### Return Type
- **Task<TResult>** - The result of the callback execution.
```

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

### Create a GridFS Bucket

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

Instantiate a GridFSBucket by passing an IMongoDatabase object to the constructor.

```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);
```

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

### Configure Server

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

Sets the host and port for the MongoDB server.

```csharp
var builder = new MongoUrlBuilder
{
    Server = new MongoServerAddress("localhost", 27017)
};
```

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

### Example Lookup Result

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

JSON representation of a document returned by a $lookup operation.

```json
// Results Truncated

{
   "restaurant": {
      "_id": ObjectId("..."),
      "name": "The Movable Feast",
      "restaurant_id": "40361606",
      "cuisine": "American",
      "address": { ... },
      "borough": "Brooklyn",
      "grades": [ ... ]
   },
   "reviews": [
      {
         "_id": ObjectId("..."),
         "restaurant_name": "The Movable Feast",
         "reviewer": "Lazlo Cravensworth",
         "review_text": "Great restaurant! 12/10 stars!"
      },
      {
         "_id": ObjectId("..."),
         "restaurant_name": "The Movable Feast",
         "reviewer": "Michael Scarn",
         "review_text": "It really was a feast"
      }
   ]
}
```

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

### HierarchicalDiscriminatorConvention BSON Output

Source: https://www.mongodb.com/docs/drivers/csharp/current/serialization/polymorphic-objects

Example BSON documents generated when using the HierarchicalDiscriminatorConvention.

```javascript
{ _id: ..., _t: "Animal", ... }
{ _id: ..., _t: ["Animal", "Cat"], ... }
{ _id: ..., _t: ["Animal", "Dog"], ... }
{ _id: ..., _t: ["Animal", "Cat", "Lion"], ... }
{ _id: ..., _t: ["Animal", "Cat", "Tiger"], ... }
```

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

### Enable Compression via MongoClientSettings

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

Configure compression by setting the Compressors property to a list of CompressorConfiguration objects.

```csharp
var settings = new MongoClientSettings()
{
   Scheme = ConnectionStringScheme.MongoDB,
   Server = new MongoServerAddress("<cluster-url>"),
   Compressors = new List<CompressorConfiguration>()
   {
      new CompressorConfiguration(CompressorType.Snappy),
      new CompressorConfiguration(CompressorType.Zlib),
      new CompressorConfiguration(CompressorType.Zstandard)
   }
};

var client = new MongoClient(settings);
```

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

### OData JSON Response

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

Example JSON response returned by the OData endpoint.

```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": [
        ...
      ]
    },

    ...

    ]
}
```

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

### Create Multiple Search Indexes

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

Demonstrates creating both a standard search index and a vector search index simultaneously using CreateMany.

```csharp
var searchModel = new CreateSearchIndexModel(
  "as_idx",
  SearchIndexType.Search,
  new BsonDocument {
    { "mappings", new BsonDocument {
      { "dynamic", true },
    } }
  }
);

var vectorModel = new CreateVectorSearchIndexModel<Movie>(
  m => m.PlotEmbedding,
  "vs_idx",
  VectorSimilarity.Euclidean,
  1536);

var models = new List<CreateSearchIndexModel> { searchModel, vectorModel };
var indexes = movieCollection.SearchIndexes.CreateMany(models);
Console.WriteLine("Created Search indexes:\n{0} {1}", indexes.ToArray());
```

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

### Polygon Query Results

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

Example JSON output for a polygon-based geospatial query.

```json
{ "_id" : ObjectId("59a47287cfa9a3a73e51e8e2"), "theaterId" : 1908 }
{ "_id" : ObjectId("59a47287cfa9a3a73e51eccb"), "theaterId" : 835 }
{ "_id" : ObjectId("59a47286cfa9a3a73e51e838"), "theaterId" : 1448 }
{ "_id" : ObjectId("59a47286cfa9a3a73e51e744"), "theaterId" : 1028 }
{ "_id" : ObjectId("59a47287cfa9a3a73e51ebe1"), "theaterId" : 609 }
{ "_id" : ObjectId("59a47287cfa9a3a73e51e8ed"), "theaterId" : 1906 }
{ "_id" : ObjectId("59a47287cfa9a3a73e51e87d"), "theaterId" : 1531 }
{ "_id" : ObjectId("59a47287cfa9a3a73e51eb63"), "theaterId" : 482 }
```

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

### ScalarDiscriminatorConvention BSON Output

Source: https://www.mongodb.com/docs/drivers/csharp/current/serialization/polymorphic-objects

Example BSON documents generated when using the default ScalarDiscriminatorConvention.

```json
{ _id: ..., _t: "Animal", ... }
{ _id: ..., _t: "Cat", ... }
{ _id: ..., _t: "Dog", ... }
{ _id: ..., _t: "Lion", ... }
{ _id: ..., _t: "Tiger", ... }
```

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

### Configure Unordered Bulk Write

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

Demonstrates using BulkWriteOptions to perform unordered operations synchronously or asynchronously.

```csharp
var models = new List<WriteModel<BsonDocument>>
{
new DeleteOneModel<BsonDocument>(
    Builders<BsonDocument>.Filter.Eq("restaurant_id", "5678")
)
};

var options = new BulkWriteOptions
{
    IsOrdered = false,
};

collection.BulkWrite(models, options);
```

```csharp
var models = new List<WriteModel<BsonDocument>>
{
new DeleteOneModel<BsonDocument>(
    Builders<BsonDocument>.Filter.Eq("restaurant_id", "5678")
)
};

var options = new BulkWriteOptions
{
    IsOrdered = false,
};

await collection.BulkWriteAsync(models, options);
```

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

### Collection Metadata Output

Source: https://www.mongodb.com/docs/drivers/csharp/current/time-series

Example output showing the structure of a time series collection.

```json
{
   "name": "september2021",
   "type": "timeseries",
   "options": {
      "timeseries": {
         "timeField": "temperature",
         "granularity": "seconds",
         "bucketMaxSpanSeconds": 3600
      }
   },
   "info": {
      "readOnly": false
   }
}
...
```

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

### Example Search Result Document

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

Represents the structure of a document returned by the search operation.

```json
{ "_id" : ObjectId("..."), "title" : "About Time", "plot" : "...", "genres" : ["Comedy", "Drama", "Romance"], "year" : 2013, "rated" : "R", "imdb" : { "rating" : 7.8, "votes" : "...", "id" : "..." } }
```

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

### Create a BsonDocument in C#

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

Construct a BsonDocument by initializing it with BsonElement key-value pairs.

```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"}
};
```

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

### Define Vector Collection Documents

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

Example JSON documents used for vector similarity operations.

```json
{ "_id": 1, "vector1": [1.0, 2.0, 3.0], "vector2": [1.0, 2.0, 3.0] },
{ "_id": 2, "vector1": [1.0, 2.0, 3.0], "vector2": [3.0, 2.0, 1.0] }
```

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

### Connect to a Replica Set

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

Specify multiple hostnames and ports in the connection string to connect to a replica set.

```csharp
using MongoDB.Driver;

// Sets the connection URI than includes the list of hosts in the replica set
const string connectionUri = "mongodb://host1:27017,host2:27017,host3:27017";

// Creates a new client and connects to the server
var client = new MongoClient(connectionUri);
```

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

### Sample Ingredients Collection Data

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

JSON representation of the ingredients collection used for aggregation examples.

```json
{ "_id" : 1, "name" : "watermelon", "is_available" : 1, "is_cheap" : 1 },
{ "_id" : 2, "name" : "onions", "is_available" : 1, "is_cheap" : 0 },
{ "_id" : 3, "name" : "eggs", "is_available" : 0, "is_cheap" : 0 },
{ "_id" : 4, "name" : "potatoes", "is_available" : 1, "is_cheap" : 1 },
{ "_id" : 5, "name" : "pasta", "is_available" : 0, "is_cheap" : 1 },
{ "_id" : 6, "name" : "cheese", "is_available" : 1 }
```

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

### Configure Change Stream with Post-Images

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

Demonstrates opening a change stream with the FullDocument option set to UpdateLookup to retrieve the post-image of updated documents.

```csharp
var pipeline = new EmptyPipelineDefinition<ChangeStreamDocument<Restaurant>>()
    .Match(change => change.OperationType == ChangeStreamOperationType.Update);

var options = new ChangeStreamOptions
{
    FullDocument = ChangeStreamFullDocumentOption.UpdateLookup,
};

using (var cursor = collection.Watch(pipeline, options))
{
    foreach (var change in cursor.ToEnumerable())
    {
        Console.WriteLine(change.FullDocument.ToBsonDocument());
    }
}
```

```csharp
var pipeline = new EmptyPipelineDefinition<ChangeStreamDocument<Restaurant>>()
    .Match(change => change.OperationType == ChangeStreamOperationType.Update);

var options = new ChangeStreamOptions
{
    FullDocument = ChangeStreamFullDocumentOption.UpdateLookup,
};

using var cursor = await collection.WatchAsync(pipeline, options);
await cursor.ForEachAsync(change =>
{
    Console.WriteLine(change.FullDocument.ToBsonDocument());
});
```

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

### Serialized JSON Output

Source: https://www.mongodb.com/docs/drivers/csharp/current/serialization/polymorphic-objects

Example of how the serialized document appears in MongoDB after applying a custom discriminator.

```json
{ "_id": "...", "_t": "myAnimalClass"}
```

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

### Duplicate key error message

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

Example of the error returned when a unique index constraint is violated.

```none
E11000 duplicate key error index
```

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

### Query Using a Multikey Index

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

Demonstrates a query that utilizes the previously created multikey index.

```csharp
// Define query parameters
var genreFilter = Builders<Movie>.Filter.AnyEq(m => m.Genres, "Animation");
var ratedFilter = Builders<Movie>.Filter.Eq(m => m.Rated, "G");
var filter = Builders<Movie>.Filter.And(genreFilter, ratedFilter);
var sort = Builders<Movie>.Sort.Ascending(m => m.Title);
var projection = Builders<Movie>.Projection
    .Include(m => m.Title)
    .Include(m => m.Rated)
    .Exclude(m => m.Id);

// Execute query
var results = collection.Find(filter).Sort(sort).Project(projection);
```

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

### Bulk Write Result Output

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

Example output returned after executing a bulk write operation.

```shell
BulkWriteResult({'writeErrors': [], 'writeConcernErrors': [], 'nInserted': 2, 'nUpserted': 0, 'nMatched': 2, 'nModified': 2, 'nRemoved': 1, 'upserted': []}, acknowledged=True)
```

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

### Configure appsettings.json

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

JSON configuration for MongoDB connection URI, database name, and collection name.

```json
{
   "Logging": {
      "LogLevel": {
         "Default": "Information",
         "Microsoft.AspNetCore": "Warning"
         }
      },
   "AllowedHosts": "*",
   "MongoDB": {
      "ConnectionURI": "<Atlas connection string>",
      "DatabaseName": "sample_mflix",
      "CollectionName": "playlist"
      }
}
```

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

### Open a GridFS Download Stream

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

Demonstrates retrieving a file by name and opening a stream to read its contents into a buffer.

```csharp
var filter = Builders<GridFSFileInfo>.Filter.Eq(x => x.Filename, "new_file");
var doc = bucket.Find(filter).FirstOrDefault();

if (doc != null)
{
    using (var downloader = bucket.OpenDownloadStream(doc.Id))
    {
        var buffer = new byte[downloader.Length];
        downloader.Read(buffer, 0, buffer.Length);

        // Process the buffer as needed
    }
}
```

```csharp
var filter = Builders<GridFSFileInfo>.Filter.Eq(x => x.Filename, "new_file");
var cursor = await bucket.FindAsync(filter);
var fileInfoList = await cursor.ToListAsync();
var doc = fileInfoList.FirstOrDefault();

if (doc != null)
{
    using (var downloader = await bucket.OpenDownloadStreamAsync(doc.Id))
    {
        var buffer = new byte[downloader.Length];
        await downloader.ReadAsync(buffer, 0, buffer.Length);

        // Process the buffer as needed
    }
}
```

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

### Vector Search Result JSON

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

Example JSON output returned by the vector search query.

```json
{ "_id" : { "$oid" : "573a13a0f29313caabd04a4f" }, "plot" : "A reporter, learning of time travelers visiting 20th century disasters, tries to change the history they know by averting upcoming disasters.", "title" : "Thrill Seekers", "score" : 0.926971435546875 }
{ "_id" : { "$oid" : "573a13d8f29313caabda6557" }, "plot" : "At the age of 21, Tim discovers he can travel in time and change what happens and has happened in his own life. His decision to make his world a better place by getting a girlfriend turns out not to be as easy as you might think.", "title" : "About Time", "score" : 0. 9267120361328125 }
{ "_id" : { "$oid" : "573a1399f29313caabceec0e" }, "plot" : "An officer for a security agency that regulates time travel, must fend for his life against a shady politician who has a tie to his past.", "title" : "Timecop", "score" : 0.9235687255859375 }
{ "_id" : { "$oid" : "573a13a5f29313caabd13b4b" }, "plot" : "Hoping to alter the events of the past, a 19th century inventor instead travels 800,000 years into the future, where he finds humankind divided into two warring races.", "title" : "The Time Machine", "score" : 0.9228668212890625 }
{ "_id" : { "$oid" : "573a13aef29313caabd2e2d7" }, "plot" : "After using his mother's newly built time machine, Dolf gets stuck involuntary in the year 1212. He ends up in a children's crusade where he confronts his new friends with modern techniques...", "title" : "Crusade in Jeans", "score" : 0.9228515625 }
{ "_id" : { "$oid" : "573a1399f29313caabcee36f" }, "plot" : "A time-travel experiment in which a robot probe is sent from the year 2073 to the year 1973 goes terribly wrong thrusting one of the project scientists, a man named Nicholas Sinclair into a...", "title" : "A.P.E.X.", "score" : 0.9199066162109375 }
{ "_id" : { "$oid" : "573a13c6f29313caabd715d3" }, "plot" : "Agent J travels in time to M.I.B.'s early days in 1969 to stop an alien from assassinating his friend Agent K and changing history.", "title" : "Men in Black 3", "score" : 0.919403076171875 }
{ "_id" : { "$oid" : "573a13d4f29313caabd98c13" }, "plot" : "Bound by a shared destiny, a teen bursting with scientific curiosity and a former boy-genius inventor embark on a mission to unearth the secrets of a place somewhere in time and space that exists in their collective memory.", "title" : "Tomorrowland", "score" : 0.9191131591796875 }
{ "_id" : { "$oid" : "573a13b6f29313caabd477fa" }, "plot" : "With the help of his uncle, a man travels to the future to try and bring his girlfriend back to life.", "title" : "Love Story 2050", "score" : 0. 917755126953125 }
{ "_id" : { "$oid" : "573a13b3f29313caabd3ebd4" }, "plot" : "A romantic drama about a Chicago librarian with a gene that causes him to involuntarily time travel, and the complications it creates for his marriage.", "title" : "The Time Traveler's Wife", "score" : 0.9172210693359375 }
```

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

### Example Change Stream Output

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

The JSON-like structure returned by a change stream when a document update occurs.

```sh
{ "_id" : { "_data" : "..." }, "operationType" : "update", "clusterTime" : Timestamp(...),
"wallTime" : ISODate("..."), "ns" : { "db" : "sample_restaurants", "coll" : "restaurants" },
"documentKey" : { "_id" : ObjectId("...") }, "updateDescription" : { "updatedFields" : { "cuisine" : "Irish" },
"removedFields" : [], "truncatedArrays" : [] } }
```

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

### Configure SCRAM via Connection String

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

Use a connection string to specify credentials and the authentication database.

```csharp
var mongoClient = new MongoClient(
   "mongodb[+srv]://<db_username>:<db_password>@<hostname>[:<port>]/?" +
   "authSource=<authenticationDb>");
```

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

### Define Inheritance Hierarchy

Source: https://www.mongodb.com/docs/drivers/csharp/current/serialization/polymorphic-objects

Basic class structure for an inheritance hierarchy used in polymorphic serialization examples.

```csharp
public class Animal
{
}

public class Cat : Animal
{
}

public class Dog : Animal
{
}

public class Lion : Cat
{
}

public class Tiger : Cat
{
}
```

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

### Create a session with custom options in C#

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

Initializes a new client session using a ClientSessionOptions object to define causal consistency and transaction-level read/write concerns.

```csharp
var client = new MongoClient("mongodb://localhost:27017");
var sessionOptions = new ClientSessionOptions
{
    CausalConsistency = true,
    DefaultTransactionOptions = new TransactionOptions(
         readConcern:  ReadConcern.Available,
         writeConcern:   WriteConcern.Acknowledged)
};

var session = client.StartSession(sessionOptions);
```

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

### Configure Kubernetes OIDC Authentication

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

Use this example to authenticate when running applications within a Kubernetes cluster.

```csharp
var connectionString = "mongodb://<hostname>[:<port>]/?authMechanism=MONGODB-OIDC" +
   "&authMechanismProperties=ENVIRONMENT:k8s";
var mongoClientSettings = MongoClientSettings.FromConnectionString(connectionString);
var client = new MongoClient(mongoClientSettings);
```

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

### Load PEM Certificate

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

Create an X509Certificate2 object directly from PEM-formatted files.

```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);
```

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

### Create MongoDBService

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

Initializes the MongoDB client and collection within a service class.

```csharp
using MongoExample.Models;
using Microsoft.Extensions.Options;
using MongoDB.Driver;
using MongoDB.Bson;

namespace MongoExample.Services;

public class MongoDBService {

    private readonly IMongoCollection<Playlist> _playlistCollection;

    public MongoDBService(IOptions<MongoDBSettings> mongoDBSettings) {
        MongoClient client = new MongoClient(mongoDBSettings.Value.ConnectionURI);
        IMongoDatabase database = client.GetDatabase(mongoDBSettings.Value.DatabaseName);
        _playlistCollection = database.GetCollection<Playlist>(mongoDBSettings.Value.CollectionName);
    }

    public async Task<List<Playlist>> GetAsync() { }
    public async Task CreateAsync(Playlist playlist) { }
    public async Task AddToPlaylistAsync(string id, string movieId) {}
    public async Task DeleteAsync(string id) { }

}
```

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

### Create OData Controller

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

Implement an OData controller to expose the restaurants collection with query support.

```csharp
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.OData.Routing.Controllers;
using MongoDB.AspNetCore.OData;
using MongoDB.Driver;
using ODataTest.Models;

namespace ODataTest.Controllers;

public class RestaurantsController : ODataController
{
    private readonly IQueryable<Restaurant> _restaurants;

    public RestaurantsController(IMongoClient client)
    {
        var database = client.GetDatabase("sample_restaurants");
        _restaurants = database.GetCollection<Restaurant>("restaurants")
            .AsQueryable();
    }

    // Registers Get endpoint and sets max documents to 5
    [MongoEnableQuery(PageSize = 5)]
    public ActionResult<IEnumerable<Restaurant>> Get()
    {
        return Ok(_restaurants);
    }
}
```

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

### Configure MongoClient with Console Logging

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

Initializes a logger factory with console output and debug level, then assigns it to the MongoClientSettings.

```csharp
using var loggerFactory = LoggerFactory.Create(b =>
{
  b.AddSimpleConsole();
  b.SetMinimumLevel(LogLevel.Debug);
});

var settings = MongoClientSettings.FromConnectionString("<connection string>");
settings.LoggingSettings = new LoggingSettings(loggerFactory);
var client = new MongoClient(settings);
```

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

### Handle Unsupported Stable API Version

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

Connecting to a server that does not support the specified API version may result in an exception.

```none
Unrecognized field 'apiVersion' on server...
```

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

### Enable Client-Side Projection with Project

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

Configure AggregateOptions to enable client-side projections when using the Project aggregation stage.

```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) });
```

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

### Define a GeoJSON Point document

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

Example of a document structure containing a GeoJSON Point object for geospatial indexing.

```json
{
   "_id" : ObjectId("59a47286cfa9a3a73e51e75c"),
   "theaterId" : 104,
   "location" : {
      "address" : {
         "street1" : "5000 W 147th St",
         "city" : "Hawthorne",
         "state" : "CA",
         "zipcode" : "90250"
      },
      "geo" : {
         "type" : "Point",
         "coordinates" : [
            -118.36559,
            33.897167
         ]
      }
   }
}
```

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

### Instantiate MongoClient with Stable API

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

Construct a ServerApi instance and assign it to MongoClientSettings before creating the MongoClient. Once instantiated, the API version cannot be changed for that client instance.

```csharp
var serverApi = new ServerApi(ServerApiVersion.V1);
var settings = new MongoClientSettings { ServerApi = serverApi };
var client = new MongoClient(settings);
```

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

### Delete a GridFS file

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

Examples showing how to locate a file by name and delete it using synchronous or asynchronous methods.

```csharp
var filter = Builders<GridFSFileInfo>.Filter.Eq(x => x.Filename, "new_file");
var doc = bucket.Find(filter).FirstOrDefault();

if (doc != null)
{
    bucket.Delete(doc.Id);
}
```

```csharp
var filter = Builders<GridFSFileInfo>.Filter.Eq(x => x.Filename, "new_file");
var cursor = await bucket.FindAsync(filter);
var fileInfoList = await cursor.ToListAsync();
var doc = fileInfoList.FirstOrDefault();

if (doc != null)
{
    await bucket.DeleteAsync(doc.Id);
}
```

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

### Retrieve Restaurant Data

Source: https://www.mongodb.com/docs/drivers/csharp-frameworks/ef-odata

Example JSON response showing the structure of restaurant data returned by the OData endpoint.

```text
{"@odata.context":"http://localhost:5236/odata/$metadata#Restaurants",
"value":[
   {"Id":"...","Name":"Tov Kosher Kitchen","Cuisine":"Jewish/Kosher",
   "Borough":"Queens","RestaurantId":"40356068"},
   {"Id":"...","Name":"Brunos On The Boulevard","Cuisine":"American",
   "Borough":"Queens","RestaurantId":"40356151"},
   {"Id":"...","Name":"Carvel Ice Cream","Cuisine":"Ice Cream, Gelato, Yogurt, Ices",
   "Borough":"Queens","RestaurantId":"40361322"},
   {"Id":"...","Name":"Sal'S Deli","Cuisine":"Delicatessen",
   "Borough":"Queens","RestaurantId":"40361618"},
   {"Id":"...","Name":"Steve Chu'S Deli & Grocery","Cuisine":"Delicatessen",
   "Borough":"Queens","RestaurantId":"40361998"}
]}
```

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

### List Database Names with IMongoClient

Source: https://www.mongodb.com/docs/drivers/csharp/current/databases-collections

Use these methods to retrieve a list of database names from your cluster.

```csharp
mongoClient.ListDatabaseNames();
```

```csharp
await mongoClient.ListDatabaseNamesAsync();
```

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

### Configure Scheme

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

Sets the connection string format. Throws an exception if set to DNS seed list format while DirectConnection is true.

```csharp
var builder = new MongoUrlBuilder
{
    Scheme = ConnectionStringScheme.MongoDBPlusSrv,
};
```

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

### Represent Memory-backed POCO in MongoDB

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

Example of how a POCO using Memory<T> fields is stored as a standard BSON array in MongoDB.

```json
{
  "_id": ...,
  "X": [ 1, 2, 3, 4, 5 ],
  "Y": [ 1, 1.409999966621399, 1.7300000190734863, 2, 2.240000009536743 ]
}
```

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

### Configuring HierarchicalDiscriminatorConvention

Source: https://www.mongodb.com/docs/drivers/csharp/current/serialization/polymorphic-objects

Examples of labeling the root class for hierarchical discriminators using attributes or manual class map registration.

```csharp
[BsonDiscriminator(RootClass = true)]
[BsonKnownTypes(typeof(Cat), typeof(Dog)]
public class Animal
{
}
```

```csharp
BsonClassMap.RegisterClassMap<Animal>(classMap => {
    classMap.AutoMap();
    classMap.SetIsRootClass(true);
});
BsonClassMap.RegisterClassMap<Cat>();
BsonClassMap.RegisterClassMap<Dog>();
BsonClassMap.RegisterClassMap<Lion>();
BsonClassMap.RegisterClassMap<Tiger>();
```

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

### Connect to a Single Server via MongoClientSettings

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

Configure direct connection settings programmatically using the MongoClientSettings class.

```csharp
using MongoDB.Driver;

var settings = MongoClientSettings.FromConnectionString("mongodb://host1:27017");
settings.DirectConnection = true;
var client = new MongoClient(settings);
```

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

### Automatic ID Generation for Guid.Empty

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

Demonstrates how the C# driver automatically generates a new GUID when inserting a document with an empty ID.

```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
```
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