What are the steps to obtain MongoDB facets using searchmeta in C#?

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To obtain MongoDB facets using searchmeta in C#, follow these steps: 1. Install the MongoDB.Driver package using NuGet package manager. 2. Create an instance of MongoClient class and connect to the MongoDB server. 3. Get a handle to the database by using the GetDatabase method of MongoClient class. 4. Get a handle to the collection you want to query by using the GetCollection method of IMongoDatabase interface. 5. Create a FacetPipelineDefinition object containing the aggregation pipeline stages required to get the facets. 6. Use the Aggregate method of IMongoCollection interface to execute the aggregation pipeline and retrieve the facet results.

Here's the code example to obtain MongoDB facets using SearchMeta in C#:

using MongoDB.Driver;
using MongoDB.Driver.Linq;

var connectionString = "<YOUR CONNECTION STRING>";
var client = new MongoClient(connectionString);
var database = client.GetDatabase("<YOUR DATABASE NAME>");
var collection = database.GetCollection<BsonDocument>("<YOUR COLLECTION NAME>");

// create a facet pipeline definition
var facetPipeline = PipelineDefinition<BsonDocument, AggregateFacetResult>.Create(
    new BsonDocument("$facet", new BsonDocument
    {
        { "categoryFacet", new BsonArray {
            new BsonDocument("$sortByCount", "$category"),
            new BsonDocument("$limit", 5)
        } },
        { "priceFacet", new BsonArray {
            new BsonDocument("$bucket", new BsonDocument
            {
                { "groupBy", "$price" },
                { "boundaries", new BsonArray { 0, 10, 20, 30 } },
                { "default", "Other" },
                { "output", new BsonDocument
                    {
                        { "count", new BsonDocument("$sum", 1) }
                    }
                }
            })
        } }
    })
);

// execute the facet pipeline
var result = collection.Aggregate()
    .AppendStage(facetPipeline)
    .FirstOrDefault();

// access the facet results
var categoryFacetResult = result.Facets["categoryFacet"].Cast<BsonDocument>().ToList();
var priceFacetResult = result.Facets["priceFacet"].Cast<BsonDocument>().ToList();