Asp.Net Core Use MongoDB

前几天在网上想找一下Asp.Net Core使用MongoDB相关的文章，也看了几篇，发现都是在写简单的例子，这样的例子是不能用在生产环境的，不能用的生产环境的。封装一个东西一定是建立在你对这个东西足够了解的前提下完成，最起码官方的文档你要看吧。

1、MongoClient 和 MongoDatabase 这两个对象的生命周期怎么处理？
2、每次插入一个document都要动态获取一个Collection吗？

先看一下官方给出的这篇文章：
https://mongodb.github.io/mongo-csharp-driver/2.0/reference/driver/connecting/

看完这篇文档我们发现MongoClient、MongoDatabase和MongoCollection都是可以重用的，而且是线程安全的。核心代码：

public class MongoRepository<T> where T : class, new()
{
    // https://mongodb.github.io/mongo-csharp-driver/2.0/reference/driver/connecting/#re-use
    private readonly MongoOptions _options;
    private static IMongoClient _mongoClient;
    private static IMongoDatabase _mongoDatabase;
    private static object _obj = new object();

    private static readonly ConcurrentDictionary<RuntimeTypeHandle, IMongoCollection<T>> _mongoCollections = new ConcurrentDictionary<RuntimeTypeHandle, IMongoCollection<T>>();
    public MongoRepository(IOptions<MongoOptions> optionsAccessor)
    {
        if (optionsAccessor == null)
        {
            throw new ArgumentNullException(nameof(optionsAccessor));
        }
        _options = optionsAccessor.Value;

        if (_mongoClient == null)
        {
            lock (_obj)
            {
                if (_mongoClient == null)
                {
                    _mongoClient = new MongoClient(_options.ConnectionString);
                    _mongoDatabase = _mongoClient.GetDatabase(_options.DataBaseName);
                }
            }
        }
    }

    public void Insert(T document)
    {
        this.GetCollection(document).InsertOne(document);
    }

    private IMongoCollection<T> GetCollection(T document)
    {
        if (_mongoCollections.TryGetValue(document.GetType().TypeHandle, out IMongoCollection<T> collection))
        {
            return collection;
        }

        collection = _mongoDatabase.GetCollection<T>(typeof(T).Name);
        _mongoCollections.TryAdd(document.GetType().TypeHandle, collection);

        return collection;
    }
}

public class MongoOptions
{
    public string ConnectionString { get; set; }
    public string DataBaseName { get; set; }
}

public static class MongoServiceCollectionExtensions
{
    public static IServiceCollection AddMongo(this IServiceCollection services, Action<MongoOptions> setupAction)
    {
        if (services == null)
        {
            throw new ArgumentNullException(nameof(services));
        }

        if (setupAction == null)
        {
            throw new ArgumentNullException(nameof(setupAction));
        }

        services.AddOptions();
        services.Configure(setupAction);
        services.AddScoped(typeof(MongoRepository<>));

        return services;
    }
}

public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc();
    services.AddMongo(options =>
    {
        options.ConnectionString = "mongodb://localhost:27017";
        options.DataBaseName = "oneaspnet";
    });
}