如何使用最新的 MongoDB C# 驱动程序根据多个条件删除复杂数组对象的嵌套数组中的元素？

Question

总体目标是能够根据 userid 和 mealid 执行膳食查找。如果找到该项目，我希望能够仅删除与 userid 和 mealid 匹配的整个元素。

目前，在 post 请求中通过 postman 发送请求对象后，我尝试使用 C# 编写查询的变体来创建构建器对象，然后过滤到找到具体的数组对象，如果userid和mealid都匹配，最后删除数组对象。最初，我遇到的问题是整个元素没有被删除，但只有嵌套在元素内部的内部数组元素被删除（没有删除，但设置回空值）。但是，现在的问题是整个数组元素根本没有被删除，我收到以下错误。 BsonArraySerializer Error from Visual Studio

有人可以帮我解决这个问题吗？

这是我通过 postman 发送的我试图删除的示例对象： Sample Postman POST request with Body data

这是我要删除的数据的示例图像： Sample Image of Json Array Elemet I'm trying to delete

您将需要 MongoDb Compass 或 Atlas、.NET Core 3.1、MongoDB C# Driver 2.0、Postman 和 .NET Core 3.1 WebApi Project/Solution 为了帮助解决这个问题。

下面是复制问题所需的代码：

Startup.cs

将这行代码添加到这个文件的Configuration方法中

services.AddScoped<IMealsRepository, MealsRepository>();

将此行添加到 ConfigureServices 方法

services.AddSingleton(sp =>
            sp.GetRequiredService<IOptions<DatabaseSettings>>().Value);

appSettings.json

将这些代码行添加到此文件

 "DatabaseSettings": {

    "ConnectionString": "your connection string to MongoDb"

}

数据库Settings.cs

    public class DatabaseSettings
    {
        public string ConnectionString { get; set; } 
    }

MealPlanModel.cs:

using MongoDB.Bson;

using MongoDB.Bson.Serialization.Attributes;

public class MealPlanModel
{

    #region MealPlanModel fields
    [BsonElement("userid")]
    public int? UserId { get; set; }

    [BsonElement("mealid")]
    public int? MealId { get; set; }

    [BsonElement("mealname")]
    public string MealName { get; set; }

    [BsonElement("mealimage")]
    public string MealImage { get; set; }

    [BsonElement("foods")]
    public FoodModel[] Foods { get; set; }

    [BsonElement("totalcalories")]
    public double TotalCalories { get; set; }

    [BsonElement("totalprotein")]
    public double TotalProtein { get; set; }

    [BsonElement("totalcarbs")]
    public double TotalCarbs { get; set; }


    [BsonElement("totalfat")]
    public double TotalFat { get; set; }

    [BsonElement("totalsugar")]
    public double TotalSugar { get; set; }

    [BsonElement("totalfiber")]
    public double TotalFiber { get;  set; }
    #endregion

    #region MealPlanModel ctor
    public MealPlanModel()
    {

    }

    public MealPlanModel(int userid, int mealid)
    {
        UserId = userid;
        MealId = mealid;
    }
}

MealPlanDto.cs

using MongoDB.Bson;

using MongoDB.Bson.Serialization.Attributes;

using System.Collections.Generic;

public class MealPlanDto

{

    [BsonId]
    public ObjectId Id { get; set; }

    [BsonElement("meals")]
    public List<MealPlanModel> MealPlans { get; set; }
}

**MealsController.cs:**


using System;

using System.Collections.Generic;

using System.IO;

using System.Linq;

using System.Security.Claims;

using System.Threading.Tasks;

using AutoMapper;

using Microsoft.AspNetCore.Authorization;

using Microsoft.AspNetCore.Http;

using Microsoft.AspNetCore.Mvc;

using Newtonsoft.Json;

[Route("api/[controller]")]

[ApiController]

public class MealsController : ControllerBase

{


    private readonly IMealsRepository _repo;

    private readonly IMapper _mapper;

    public MealsController(IMealsRepository repo, IMapper mapper)
    {
        _repo = repo;

        _mapper = mapper;

    } 


    [HttpGet, Route("CheckConnection")]

    public async Task<IActionResult> CheckConnection()

    {

        var result = await _repo.CheckConnection();

        if (result == null || result.Count <= 0)

            return BadRequest("Failed to connect to database.");

        return Ok("Database connection was successful");

    }

    [HttpPost("deletecustommeal")]

    public async Task<IActionResult> DeleteCustomMealPlan(int id)

    {

      var requestBody = await new StreamReader(HttpContext.Request.Body).ReadToEndAsync();
      var mealPlanToDelete = JsonConvert.DeserializeObject<MealPlanModel>(requestBody);
      MealPlanDto deleteMealPlan = new MealPlanDto();
      deleteMealPlan.MealPlans = new List<MealPlanModel>();
      deleteMealPlan.MealPlans.Add(mealPlanToDelete);
      var result = await _repo.DeleteCustomMealPlanById(deleteMealPlan);
      if (!result)
         return BadRequest("Failed to delete meal");
      return Ok("Successfully deleted meal plan");
    }

}

MealsRepository.cs

using Microsoft.Extensions.Configuration;

using MongoDB.Bson;

using MongoDB.Driver;

using System;

using System.Collections.Generic;

using System.Threading.Tasks;

public class MealsRepository : IMealsRepository

{

    private readonly MongoClient _client;

    private readonly IMongoDatabase _database;

    private readonly IMongoCollection<MealPlanDto> _userMealsCollection;

    public MealsRepository(IConfiguration configuration)
    {
        _client = new 
          MongoClient(configuration.GetSection("DatabaseSettings").GetSection("ConnectionString").Value);
        _database = _client.GetDatabase("MealsDb");
        _userMealsCollection = _database.GetCollection<MealPlanDto>("meal");
    }

    public async Task<List<BsonDocument>> CheckConnection()
    {
        List<BsonDocument> list = await _database.ListCollections().ToListAsync();
        var populatedList = (list != null && list.Count > 0) ? list : null;
        return populatedList;
    }

    public async Task<bool> DeleteCustomMealPlanById(MealPlanDto mealPlanToDelete)

    {
        var builder = Builders<MealPlanDto>.Filter;
        var filter = builder.Eq(x => x.MealPlans[0].UserId, mealPlanToDelete.MealPlans[0].UserId);

        var update = Builders<MealPlanDto>.Update.PullFilter(
            p => (IEnumerable<MealPlanModel>)p.MealPlans[0],
            f => f.MealId.Value == mealPlanToDelete.MealPlans[0].MealId);

        try
        {
            await _userMealsCollection.UpdateOneAsync(filter, update);
            return true;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Failed to delete meal plan. {ex} occured.");
            return false;
        }
    }

}

Answer 1

感谢所有试图为我的上述问题找到答案的人，但我实际上发现了一个简单的解决方案

我只是将 Repository.cs 文件中的上述方法替换为以下方法，效果非常好

public bool DeleteCustomMealPlanForUserById(MealPlanModel mealPlanToDelete)
    {
        var result = _customUserMealsCollection.DeleteOne(p => p.MealPlans[0].UserId == mealPlanToDelete.UserId
            && p.MealPlans[0].MealId == mealPlanToDelete.MealId);

        return result.DeletedCount != 0;
    }

如何使用最新的 MongoDB C# 驱动程序根据多个条件删除复杂数组对象的嵌套数组中的元素？

How can I use latest MongoDB C# Driver to delete an element within a nested array of complex array objects based on multiple conditions?

c#

multidimensional-array

mongodb

mongodb-csharp-2.0

.net-core-3.1