Code snippets for the MongoDB Atlas Vector Search with C# and Blazor tutorial

app.css

.search-bar {
  padding: 5%; 
}

.search-bar-button {
  padding: 4px; 
}

EmbeddingResponse.cs

namespace SeeSharpMovies.Models
{
    public class EmbeddingResponse
    { 
        public string @object { get; set; }
        public List<Data> data { get; set; }
        public string model { get; set; }
        public Usage usage { get; set; }
    }

    public class Data
    {
        public string @object { get; set; }
        public int index { get; set; }
        public List<double> embedding { get; set; }
    }

    public class Usage
    {
        public int prompt_tokens { get; set; }
        public int total_tokens { get; set; }
    }
}

GetEmbeddingsFromText.cs

private async Task<List<double>> GetEmbeddingsFromText(string text)
    {


        Dictionary<string, object> body = new Dictionary<string, object>
        {
            { "model", "text-embedding-ada-002" },
            { "input", text }
        };


        _httpClient.BaseAddress = new Uri("https://api.openai.com");
        _httpClient.DefaultRequestHeaders.Add("Authorization", $"Bearer {_openAPIKey}");

        string requestBody = JsonSerializer.Serialize(body);
        StringContent requestContent =
            new StringContent(requestBody, Encoding.UTF8, "application/json");

        var response = await _httpClient.PostAsync("/v1/embeddings", requestContent)
            .ConfigureAwait(false);

        if (response.IsSuccessStatusCode)
        {
            string responseBody = await response.Content.ReadAsStringAsync();
            EmbeddingResponse embeddingResponse = JsonSerializer.Deserialize<EmbeddingResponse>(responseBody);
            return embeddingResponse.data[0].embedding;
        }

        return new List<double>();
    }

Home.razor

@page "/"
@inject MongoDBService MongoDBService
@rendermode InteractiveServer

<header class="top-bar">
        <a href="/">See Sharp Movies</a>
    <div class="form-inline search-bar">
        <input class="form-control mr-sm-2"
               type="search" placeholder="Search"
               aria-label="Search"               
               @bind="searchTerm">
        <button class="btn btn-outline-success my-2 my-sm-0" @onclick="SearchMovies">Search</button>
    </div>
    </header>

<div class="moviecard-container">
    @foreach (var movie in movies)
    {
        <div class="moviecard">
            <MovieCard Movie="@movie" />
        </div>
    }
</div>

<div class="pagination-controls">
    <button disabled="@isPreviousDisabled" @onclick="GoToPreviousPage"> Previous</button>
    <span>Page @currentPage</span>
    <button @onclick="GoToNextPage" disabled="@isNextDisabled">Next</button>  
</div>

@code {

    bool isPreviousDisabled;
    bool isNextDisabled;
    int currentPage = 1;
    int pageSize = 25;

    string searchTerm = "";
    IEnumerable<Movie> movies;

    protected override async Task OnInitializedAsync()
    {
        movies = MongoDBService.GetMoviesPerPage(currentPage, pageSize);
    }

    private void SearchMovies()
    {
        if (string.IsNullOrWhiteSpace(searchTerm))
        {
            movies = MongoDBService.GetAllMovies();
        }
        else
        {
            movies = MongoDBService.MovieSearch(searchTerm);
        }
    }


    private void GoToPreviousPage()
    {
       
        if (currentPage > 1)
        {
            currentPage--;           
            movies = MongoDBService.GetMoviesPerPage(currentPage, pageSize);
        }
    }

    private void GoToNextPage()
    {
      
        currentPage++;
        movies = MongoDBService.GetMoviesPerPage(currentPage, pageSize);
    }
}

Movie.cs

using MongoDB.Bson;
using MongoDB.Bson.Serialization.Attributes;

namespace SeeSharpMovies.Models;


public class Movie
{
   [BsonId]
   [BsonElement("_id")]
   public ObjectId Id { get; set; }
   
   [BsonElement("plot")]
   public string Plot { get; set; }

   [BsonElement("genres")]  
   public string[] Genres { get; set; }

   [BsonElement("runtime")]
   public int Runtime { get; set; }

   [BsonElement("cast")]
   public string[] Cast { get; set; }

   [BsonElement("num_mflix_comments")]
   public int NumMflixComments { get; set; }

   [BsonElement("poster")]
   public string Poster { get; set; }

   [BsonElement("title")]
   public string Title { get; set; }

   [BsonElement("fullplot")]
   public string FullPlot { get; set; }

   [BsonElement("languages")]
   public string[] Languages { get; set; }

   [BsonElement("directors")]
   public string[] Directors { get; set; }

   [BsonElement("writers")]
   public string[] Writers { get; set; }

   [BsonElement("awards")]
   public Awards Awards { get; set; }
   
   [BsonElement("year")]
   public string Year { get; set; }

   [BsonElement("imdb")]
   public Imdb Imdb { get; set; }

   [BsonElement("countries")]
   public string[] Countries { get; set; }

   [BsonElement("type")]
   public string Type { get; set; }

   [BsonElement("plot_embedding")]
   public float[] PlotEmbedding { get; set; }

}

public class Awards
{
   [BsonElement("wins")]
   public int Wins { get; set; }
   
   [BsonElement("nominations")]
   public int Nominations { get; set; }
   
   [BsonElement("text")]
   public string Text { get; set; }
}

public class Imdb
{
   [BsonElement("rating")]
   public float Rating { get; set; }
   
   [BsonElement("votes")]
   public int Votes { get; set; }
   
   [BsonElement("id")]
   public int Id { get; set; }
}

MovieSearch.cs

public IEnumerable<Movie> MovieSearch(string textToSearch)
    {

        var vector = GetEmbeddingsFromText(textToSearch).Result.ToArray();

        var vectorOptions = new VectorSearchOptions<Movie>()
        {
            IndexName = "vector_index",
            NumberOfCandidates = 150
        };

        var movies = _movies.Aggregate()
            .VectorSearch(movie => movie.PlotEmbedding, vector, 150, vectorOptions)
            .Project<Movie>(Builders<Movie>.Projection
            .Include(m => m.Title)
            .Include(m => m.Plot))
            .ToList();

        return movies;
    }