0

这是代码： 控制器：


        //POST api/substances
        [HttpPost]
        [ServiceFilter(typeof(ValidateNameExistsAttribute<Substance>))]
        public ActionResult<SubstanceReadDto> CreateSubstance([FromBody]SubstanceSaveDto dto)
        {
            var substanceModel = _mapper.Map<Substance>(dto);
            _repository.CreateSubstance(substanceModel);
            _repository.SaveChanges();

            var substanceReadDto = _mapper.Map<SubstanceReadDto>(substanceModel);

            return CreatedAtRoute(nameof(GetSubstanceById), new {substanceReadDto.Id}, substanceReadDto);
        }

筛选

using System.Linq;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Filters;
using Pharmacy.Data;
using Pharmacy.Models;

namespace Pharmacy.Filters
{
    public class ValidateNameExistsAttribute<T> : IActionFilter where T : class, INameEntity
    {
        private readonly PharmacyContext _context;

        public ValidateNameExistsAttribute(PharmacyContext context)
        {
            _context = context;
        }

        public void OnActionExecuted(ActionExecutedContext context)
        {
        }

        public void OnActionExecuting(ActionExecutingContext context)
        {
            if (context.ActionArguments.ContainsKey("dto"))
            {
                var entity = new object();

                var dto = context.ActionArguments["dto"] as INameDto;
                if (dto == null)
                {
                    context.Result = new BadRequestObjectResult("Invalid request body");
                    return;
                }

                if (context.ActionArguments.ContainsKey("id"))
                {
                    var id = (int) context.ActionArguments["id"];
                    entity = _context.Set<T>().SingleOrDefault(it => String.Equals(it.Name, dto.Name, StringComparison.OrdinalIgnoreCase) && it.Id != id);
                }
                else
                {
                    entity = _context.Set<T>().SingleOrDefault(it => String.Equals(it.Name, dto.Name, StringComparison.OrdinalIgnoreCase));
                }

                if (entity != null)
                {
                    var problemDetails = new ProblemDetails
                    {
                        Title = "Duplicate resource",
                        Detail = $"A record with provided name {dto.Name} already exists",
                        Instance = context.HttpContext.Request.Path
                    };

                    context.Result = new ObjectResult(problemDetails)
                    {
                        StatusCode = 409
                    };
                }
            }
        }
    }
}

这是错误消息：代码有什么问题？

{ "type": "https://tools.ietf.org/html/rfc7231#section-6.6.1", "title": "LINQ 表达式 'DbSet\r\n .Where(s => string.Equals (\r\na: s.Name, \r\nb: __dto_Name_0, \r\n comparisonType: OrdinalIgnoreCase))' 无法翻译。要么以可翻译的形式重写查询，要么显式切换到客户端评估通过插入对 AsEnumerable()、AsAsyncEnumerable()、ToList() 或 ToListAsync() 的调用。请参阅https://go.microsoft.com/fwlink/?linkid=2101038了解更多信息。”、“状态”：500、“详细信息”：“在 Microsoft.EntityFrameworkCore.Query.QueryableMethodTranslatingExpressionVisitor.g__CheckTranslated|8_0（ShapedQueryExpression 已翻译，<>c__DisplayClass8_0&）\r\n 在 Microsoft.EntityFrameworkCore.Query.QueryableMethodTranslatingExpressionVisitor。 VisitMethodCall(MethodCallExpression methodCallExpression)\r\n 在 Microsoft.EntityFrameworkCore.Query.RelationalQueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression)\r\n 在 System.Linq.Expressions.MethodCallExpression.Accept(ExpressionVisitor visitor)\r\n 在 System.Linq。 Expressions.ExpressionVisitor.Visit（表达式节点）\r\n 在 Microsoft.EntityFrameworkCore.Query.QueryableMethodTranslatingExpressionVisitor。VisitMethodCall(MethodCallExpression methodCallExpression)\r\n 在 Microsoft.EntityFrameworkCore.Query.RelationalQueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression)\r\n 在 System.Linq.Expressions.MethodCallExpression.Accept(ExpressionVisitor visitor)\r\n 在 System.Linq。 Expressions.ExpressionVisitor.Visit(表达式节点)\r\n 在 Microsoft.EntityFrameworkCore.Query.QueryCompilationContext.CreateQueryExecutor[TResult](表达式查询)\r\n 在 Microsoft.EntityFrameworkCore.Storage.Database.CompileQuery[TResult](表达式查询, 布尔异步）\r\n 在 Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore[TResult]（IDatabase 数据库，表达式查询，IModel 模型，布尔异步）\r\n 在 Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler .<>c__DisplayClass9_01.<Execute>b__0()\r\n at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQueryCore[TFunc](Object cacheKey, Func1 个编译器）\r\n 在 Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQuery[TResult]（对象 cacheKey，Func 1 compiler)\r\n at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.Execute[TResult](Expression query)\r\n at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.Execute[TResult](Expression expression)\r\n at System.Linq.Queryable.SingleOrDefault[TSource](IQueryable1 源，表达式1 predicate)\r\n at Pharmacy.Filters.ValidateNameExistsAttribute1.OnActionExecuting(ActionExecutingContext context) in D:\.Pharmac Project\pharmac\Filters\ValidateNameExistsAttribute.cs:line 43\r\n at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state , Boolean& isCompleted)\r\n 在 Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeNextActionFilterAsync()\r\n--- 从先前引发异常的位置结束堆栈跟踪 ---\r\n 在 Microsoft。 AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow(ActionExecutedContextSealed context)\r\n 在 Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)\r\n 在 Microsoft.AspNetCore .Mvc.Infrastructure.ControllerActionInvoker。InvokeInnerFilterAsync()\r\n--- 从先前引发异常的位置结束堆栈跟踪 ---\r\n 在 Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|19_0（ResourceInvoker 调用程序，任务 lastTask，状态接下来，Scope 范围，对象状态，Boolean isCompleted）\r\n 在 Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|17_0（ResourceInvoker 调用程序，任务任务，IDisposable 范围）\r\n 在 Microsoft.AspNetCore.Routing。 EndpointMiddleware.g__AwaitRequestTask|6_0（端点端点、任务 requestTask、ILogger 记录器）\r\n 在 Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext)\r\n 在 Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext , ISwaggerProvider swaggerProvider)\r\n 在 Microsoft.AspNetCore.Authorization.AuthorizationMiddleware。在 Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke（HttpContext 上下文）中调用（HttpContext 上下文）\r\n 在 Microsoft.AspNetCore.Diagnostics 中的 Serilog.AspNetCore.RequestLoggingMiddleware.Invoke（HttpContext httpContext）\r\n。 ExceptionHandlerMiddleware.g__Awaited|6_0(ExceptionHandlerMiddleware 中间件, HttpContext 上下文, 任务任务)", "traceId": "|9542c43b-43548354a97cc054." }

4

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