當我嘗試將查詢結果傳遞給Dto物件“錯誤映射型別”時出現例外

我正在嘗試使用 Linq-to-SQL 對我的資料庫進行基本查詢

查詢正確完成，我用 LinqPad 嘗試過，它可以作業，問題（我想是的，我不是專家）是在嘗試將查詢結果傳遞給我的DTO object DtoAsset

我用谷歌搜索了它，但我無法理解錯誤的原因。

AutoMapper.AutoMapperMappingException：錯誤映射型別。

映射型別：EntityQueryable 1 -> List1 Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable 1[[<>f__AnonymousType13[[System.Int32, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.String, System.Private .CoreLib，版本=6.0.0.0，文化=中性，PublicKeyToken=7cec85d7bea7798e]，[System.Int32，System.Private.CoreLib，版本=6.0.0.0，文化=中性，PublicKeyToken=7cec85d7bea7798e]]，API，版本=1.0 .0.0, Culture=neutral, PublicKeyToken=null]] -> System.Collections.Generic.List`1[[API.Dtos.DtoAsset, API, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]] -- -> AutoMapper.AutoMapperMappingException：缺少型別映射配置或不支持的映射。

映射型別：<>f__AnonymousType1 3 -> DtoAsset <>f__AnonymousType13[[System.Int32, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.String, System.Private.CoreLib, Version=6.0.0.0 , Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.Int32, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]] -> API.Dtos.DtoAsset at lambda_method19(Closure , <> f__AnonymousType1 3 , DtoAsset , ResolutionContext ) at lambda_method18(Closure , Object , List1 , ResolutionContext ) --- 內部例外堆疊跟蹤結束 --- 在 C:\WebApp\backend\API\ 中 API.Controllers.InventoryController.SearhInventory() 的
lambda_method18(Closure , Object , List`1 , ResolutionContext )
Controllers\InventoryControllers.cs：
lambda_method6 的第 47 行（閉包，物件）

端點

[HttpGet("Search/")]
public async Task<ActionResult<List<DtoAsset>>> SearhInventory()
{
    var query =
        from a in context.Assets
        join i in context.Inventories
        on a.inventory_id equals i.inventory_id
        where a.inventory_id == 1
        select new { asset_id = a.asset_id, name = a.name, inventory_id = a.inventory_id };

    await query.ToListAsync();

    List<DtoAsset> dto = mapper.Map<List<DtoAsset>>(query);
    return dto;
}

映射器

namespace API.Map
{
    public class AutoMapper : Profile
    {
        public AutoMapper()
        {
            #region Inventory
            CreateMap<Inventory, DtoInventory>().ReverseMap();
            //Create
            CreateMap<DtoInventoryCreate, Inventory>();
            #endregion

            #region Asset
            CreateMap<Asset, DtoAsset>().ReverseMap();
            //Create
            CreateMap<DtoAssetCreate, Asset>();

            #endregion
        }
    }
}

楷模

public class Asset
{
    public int asset_id { get; set; }
    public int code { get; set; }
    public string name { get; set; }
    public int inventory_id { get; set; }
    public Inventory Inventory { get; set; }
}

public class Inventory
{
    public int inventory_id { get; set; }
    public string name { get; set; }
    public string location { get; set; }
    public int status { get; set; }
    public DateTime? created_date { get; set; }
    public List<Asset> Assets { get; set; }

}

DTO

namespace API.Dtos
{
    public class DtoAsset
    {
        public int asset_id { get; set; }
        public int code { get; set; }
        public string name { get; set; }
        public int inventory_id { get; set; }
    }

    public class DtoInventory
    {
        public int inventory_id { get; set; }
        public string name { get; set; }
        public string location { get; set; }
        public bool status { get; set; }
        public DateTime created_date { get; set; }
        public List<Asset> Assets { get; set; }
    }
}

程式

using System.Text.Json.Serialization;
using API.Data;
using Microsoft.EntityFrameworkCore;

var MyAllowSpecificOrigins = "_myAllowSpecificOrigins";

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddCors(options =>
{
    options.AddPolicy(name: MyAllowSpecificOrigins,
                      policy =>
                      {
                          policy.WithOrigins("http://localhost:3000")
                            .AllowAnyMethod()
                            .AllowAnyHeader();
                      });
});
//  AutoMapper
builder.Services.AddAutoMapper(typeof(Program));

// MS SQL Connector start...
builder.Services.AddDbContext<ApplicationDbContext>(options =>
    options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection")));
// ...end

builder.Services.AddControllers().AddJsonOptions(
    x => x.JsonSerializerOptions.ReferenceHandler = ReferenceHandler.IgnoreCycles);
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

var app = builder.Build();

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}
//      SSL Certifitate = Disable
// app.UseHttpsRedirection();

// CORS!
app.UseCors(MyAllowSpecificOrigins);
app.UseAuthorization();

app.MapControllers();

app.Run();

uj5u.com熱心網友回復：

您的 query.ToList() 不會回傳資產串列，而是回傳具有與資產相同屬性的新匿名物件的串列。你想要的是：

query = ... select new Asset { asset_id = a.asset_id, name = a.name, inventory_id = a.inventory_id };

編輯：我剛剛注意到，你也呼叫了 toList()，但你沒有在任何地方分配結果。

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