具有多個集合和多個資料庫的ASP.NETCoreWebAPI和MongoDB

有了這個問題ASP.NET Core Web API and MongoDB with multiple Collections答案，我可以看到單例和延遲初始化對 mongodb 的WITH 單個資料庫和多個集合的完美使用。

啟動.cs

public void ConfigureServices(IServiceCollection services)
    {
        services.AddSwaggerGen(c =>
        {
            c.SwaggerDoc("v1", new OpenApiInfo { Title = "Asset Model API", Version = "v1" });
        });

        ConfigureMongoDb(services);

        services.AddControllers()
            .AddJsonOptions(options => options.JsonSerializerOptions.PropertyNamingPolicy = null);
    }

    private void ConfigureMongoDb(IServiceCollection services)
    {
        var settings = GetMongoDbSettings();
        services.AddSingleton(_ => CreateMongoDatabase(settings));

        AddMongoDbService<AuthorService, Author>(settings.AuthorsCollectionName);
        AddMongoDbService<BookService, Book>(settings.BooksCollectionName);

        void AddMongoDbService<TService, TModel>(string collectionName)
        {
            services.AddSingleton(sp => sp.GetRequiredService<IMongoDatabase>().GetCollection<TModel>(collectionName));
            services.AddSingleton(typeof(TService));
        }
    }

    private DatabaseSettings GetMongoDbSettings() =>
        Configuration.GetSection(nameof(DatabaseSettings)).Get<DatabaseSettings>();

    private static IMongoDatabase CreateMongoDatabase(DatabaseSettings settings)
    {
        var client = new MongoClient(settings.ConnectionString);
        return client.GetDatabase(settings.DatabaseName);
    }

圖書服務.cs

public class BookService
{
    private readonly IMongoCollection<Book> _books;

    public BookService(IMongoCollection<Book> books)
    {
        _books = books;
    }

    public List<Book> Get() => _books.Find(book => true).ToList();
}

BooksController.cs

public class BooksController : ControllerBase
{
    private readonly BookService _bookService;

    public BooksController(BookService bookService)
    {
        _bookService = bookService;
    }

    [HttpGet]
    public ActionResult<List<Book>> Get() => _bookService.Get();
}

我的用例：我有多個資料庫，我的 API 端點將接受database name作為引數之一

  [HttpGet]
    public ActionResult<List<Book>> Get(string dbName) => _bookService.Get(dbName);

現在的問題是我的service類和ConfigureMongoDb啟動類的方法需要進行哪些更改，以便我仍然可以獲得延遲初始化和單例支持？

uj5u.com熱心網友回復：

您可以創建一個可以根據資料庫名稱提供集合的類，而不是將 IMongoCollection 注入服務（BooksService，...），例如

public class MongoCollectionProvider
{
  private readonly IMongoClient _client;

  public MongoDbCollectionProvider(IMongoClient client) 
  {
    _client = client;
  }

  public IMongoCollection<T> GetCollection<T>(string database, string collection)
  {
    var db = _client.GetDatabase(database);
    return db.GetCollection<T>(collection);
  }
}

然后，您可以將此類注入服務并在查詢資料庫之前檢索集合，例如

public class BookService
{
    private readonly MongoCollectionProvider _prov;
    private readonly string _coll;

    public BookService(MongoCollectionProvider prov, string coll)
    {
        _prov = prov;
        _coll = coll;
    }

    public List<Book> Get(string dbName) => _prov.GetCollection<Book>(dbName, _coll).Find(book => true).ToList();
}

您可以像這樣注冊服務：

private void ConfigureMongoDb(IServiceCollection services)
{
  var settings = GetMongoDbSettings();
  services.AddSingleton(_ => CreateMongoClient(settings));
  services.AddSingleton<MongoCollectionProvider>();

  services.AddSingleton(sp => 
  {
    var prov = sp.GetRequiredService<MongoCollectionProvider>();
    return new AuthorsService(prov, settings.AuthorsCollectionName);
  }
  services.AddSingleton(sp => 
  {
    var prov = sp.GetRequiredService<MongoCollectionProvider>();
    return new BooksService(prov, settings.BooksCollectionName);
  }
}

private DatabaseSettings GetMongoDbSettings() => Configuration.GetSection(nameof(DatabaseSettings)).Get<DatabaseSettings>();

private static IMongoDatabase CreateMongoClient(DatabaseSettings settings)
{
  return new MongoClient(settings.ConnectionString);
}

如果要將資料庫限制為特定的資料庫，可以將 MongoCollectionProvider 更改為僅接受已注冊的資料庫名稱。

標籤：C＃ mongodb asp.net 核心 依赖注入 单身人士

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