我正在做一个Asp.net core 5项目。我创建了一个action filter适用于HttPost特别是 的操作create，此过滤器将检查数据库中是否已存在具有从model.
我如何使用它：
过滤器应该接收entity要签入的，以及要签入的属性名称，以及在存在记录的情况下显示entity的错误消息。
过滤器定义： 我觉得有点复杂
public class RecordShouldNotExistFilterAttribute:TypeFilterAttribute
{
public RecordShouldNotExistFilterAttribute( Type entityType, string errorMessage= "Existe déjà", params string[] propertiesToBeChecked) : base( typeof(RecordShouldNotExistFilter<>).MakeGenericType(entityType))
{
Arguments = new object[] {errorMessage , propertiesToBeChecked};
}
}
public class RecordShouldNotExistFilter<TEntity>:IActionFilter where TEntity : class
{
private readonly AppDbContext _dbContext;
public string[] PropertiesToBeChecked { get; set; }
public string ErrorMessage { get; set; }
public RecordShouldNotExistFilter( AppDbContext dbContext ,string errorMessage,params string[] propertiesToBeChecked)
{
_dbContext = dbContext;
PropertiesToBeChecked = propertiesToBeChecked;
ErrorMessage = errorMessage;
}
public void OnActionExecuting( ActionExecutingContext context )
{
Expression queryExpression = null;
context.ActionArguments.TryGetValue( "model" , out var model );
var param = Expression.Parameter(typeof(TEntity));
foreach ( var property in PropertiesToBeChecked )
{
var propValue = model?.GetType().GetProperty( property )?.GetValue( model );
var equalExpression = Expression.Equal( left : Expression.Property( param , property) , right : Expression.Constant( propValue ) );
queryExpression = queryExpression == null ? equalExpression : Expression.And( queryExpression , equalExpression );
}
var condition = Expression.Lambda<Func<TEntity , bool>>( queryExpression , param );
var result = _dbContext.Set<TEntity>().Where( condition );
if ( result.Any() )
{
context.Result = RedirectToActionResult( action : "ExistError" , controller : "/Exception" ,errorModel: new ErrorModel()
{
Title = "Existe déjà" ,
Description = $"{ErrorMessage}" ,
ReturnUrl = "/Dashboard"
} );
}
}
public void OnActionExecuted( ActionExecutedContext context )
{
}
#region Private methods
private static RedirectToActionResult RedirectToActionResult(string action, string controller, ErrorModel errorModel)
{
return new RedirectToActionResult(action, controller, errorModel);
}
#endregion
}
与动作一起使用的示例：
[RecordShouldNotExistFilter(entityType: typeof(PedagogicalSequence), errorMessage: "A record with the same ID already exists",propertiesToBeChecked: nameof(Branche.Id))]
public IActionResult Create(Branche model)
{
//Some logic here
}
问题：
问题出在
Action我收到此错误 InvalidOperationException：未为类型“System.Int32”和“System.String”定义二元运算符 Equal。System.Linq.Expressions.Expression.GetEqualityComparisonOperator（ExpressionType binaryType，字符串 opName，表达式左，表达式右，bool liftToNull）
错误画面：
请帮助解决这个问题？