如何避免循环引用ASP.NET Core MVC [HttpPost("add-recipe")] Web API [英] How to avoid the circular referencing asp.net core mvc [HttpPost("add-recipe")] web api

问题描述

我的项目是带有食谱的应用程序(烹饪).NET Core 5.0

My project is Application with Recipes (cooking) .NET Core 5.0

我在添加新配方(HttpPost)Web API时遇到问题

And i have problem with adding a new recipe (HttpPost) web api

关于邮递员，我的答复是:

On postman my response is:

检测到可能的对象周期.这可能是由于循环引起的，或者如果对象深度大于允许的最大深度32.请考虑对JsonSerializerOptions使用ReferenceHandler.Preserve支持循环."

当我创建新食谱时，应使用recipeToCreateDto而不是包含所有属性(循环引用)的食谱

When i'm creating a new recipe it should use recipeToCreateDto instead of Recipe - which contains all properties (circular referencing)

您能帮我如何使其正常运行吗?如何映射等.

Could you help me how to make it working properly. How to map etc.

https://i.postimg.cc/Mphv7zRH/screen.png <-屏幕在这里

https://i.postimg.cc/Mphv7zRH/screen.png <- screen here

我正在使用AutoMapper映射类和存储库模式.

I'm using AutoMapper for mapping classes and Repository Pattern.

public class AppUser
    {
        public int Id { get; set; }
        public string UserName { get; set; }
        public ICollection<Recipe> Recipes {get; set;} 
    }
}

用户有很多食谱.

 public class Recipe
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public AppUser AppUser { get; set; }
        public int AppUserId { get; set; }
    }

数据传输对象

public class RecipeForCreateDto
    {
        [Required]
        [StringLength(50, MinimumLength = 3, ErrorMessage = "You must specify name between 3 and 50 characters")]
        public string Name { get; set; }
        public int AppUserId { get; set; }
        public int AuthorId { get; set; }
    }

在我的AutoMapperProfiles.cs中

In my AutoMapperProfiles.cs

public class AutoMapperProfiles : Profile
    {
        public AutoMapperProfiles()
        {
        CreateMap<RecipeForCreateDto, Recipe>();
        }

配方界面

  public interface IRecipeRepository
    {
      Task<Recipe> AddNewRecipe(Recipe recipe);
    }

    public class RecipeRepository : IRecipeRepository
    {
        private readonly DataContext _context;
        private readonly IMapper _autoMapper;
        public RecipeRepository(DataContext context, IMapper autoMapper)
        {
            _autoMapper = autoMapper;
            _context = context;
        }

 public async Task<Recipe> AddNewRecipe(Recipe recipe)
        {
            await _context.Recipes.AddAsync(recipe);
            await _context.SaveChangesAsync();

            return recipe;
        }

}

用户控制器:

User.GetUsername()是获取用户名的静态方法.

User.GetUsername() is static method that is getting User's username.

[HttpPost("add-recipe")]
        public async Task<ActionResult> AddNewRecipe(RecipeForCreateDto recipeForCreateDto)
        {
            var userFromRepo = await _userRepository.GetUserByUsernameAsync(User.GetUsername());

            recipeForCreateDto.Name = recipeForCreateDto.Name.ToLower();

            if (await _recipeRepository.RecipeExists(recipeForCreateDto.Name))
                return BadRequest("Recipe with that name already exists!");

            var recipeToCreate = _autoMapper.Map<Recipe>(recipeForCreateDto);

            recipeToCreate.AppUserId = userFromRepo.Id;


            var createdRecipe = await _recipeRepository.AddNewRecipe(recipeToCreate); // here is problem 

            var recipeToReturn = _autoMapper.Map<RecipeForDetailDto>(createdRecipe);


            return CreatedAtRoute("GetRecipe", new { controller = "Recipes", id = createdRecipe.Id }, recipeToReturn);
        }

推荐答案

检测到可能的对象周期.这可能是由于循环或对象深度大于最大允许深度之32.考虑在以下位置使用ReferenceHandler.PreserveJsonSerializerOptions以支持周期."

"A possible object cycle was detected. This can either be due to a cycle or if the object depth is larger than the maximum allowed depth of 32. Consider using ReferenceHandler.Preserve on JsonSerializerOptions to support cycles."

对于此问题，您可以在startup.cs ConfigureServices 方法中添加以下代码:

For this issue , you can add the following code in startup.cs ConfigureServices method:

services.AddControllersWithViews()
    .AddNewtonsoftJson(options =>
    options.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore
);

这篇关于如何避免循环引用ASP.NET Core MVC [HttpPost("add-recipe")] Web API的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！