Entity Framework 核心没有带有错误消息的重复条目

Question

使用 MVC-EFC 和 ErrorMessage 避免重复条目的最佳方法是什么 return

型号Test.cs

public class Test
{
    public int Id { get; set; }

    [Required(ErrorMessage = "Select a Name")]
    [StringLength(50, ErrorMessage = "Max 50 character")]
    public string Name { get; set; }

    [StringLength(100, ErrorMessage = "Max 100 character")]
    public string Text { get; set; }
}

我将 ApiController 与 "ErrorMessage" return 一起使用。对于列 "Name"，我不想要重复项和错误消息 return，例如 "Entry already available!" 什么是最好的方法？

Answer 1

尝试实现自定义 ValidationAttribute

客户ValidationAttribute

public class UniqueValidation : ValidationAttribute
{
private readonly string _errorMessage;
public UniqueValidation(string ErrorMessage)
{
    _errorMessage = ErrorMessage;
}
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
    if (validationContext != null && typeof(IName).IsAssignableFrom(validationContext.ObjectType))
    {
        ApplicationDbContext db = validationContext.GetService(typeof(ApplicationDbContext)) as ApplicationDbContext;
        IQueryable<IName> result = db.GetType().GetMethod("Set").MakeGenericMethod(validationContext.ObjectType).Invoke(db, null) as IQueryable<IName>;
        var v = result.FirstOrDefault(u => u.Name == ((IName)validationContext.ObjectInstance).Name);
        if (v != null)
        {
            return new ValidationResult(_errorMessage);
        }
    }
    return ValidationResult.Success;
}
 }

使用

public class File: IName
{
public int Id { get; set; }
[UniqueValidation("FileName is exist")]
public string Name { get; set; }
[InverseProperty("Avatar")]
public ICollection<ApplicationUser> Users { get; set; }
}

public interface IName
 {
string Name { get; set; }
 }

Entity Framework 核心没有带有错误消息的重复条目

Entity Framework Core no duplicate entries with ErrorMessage

asp.net-core

ef-core-2.1