如何使用Fluent验证针对实体框架核心字段属性进行验证

问题描述

我正在尝试通过Entity Framework Core的.HasMaxLength属性进行验证.

I'm trying to validate against the .HasMaxLength property from Entity Framework Core.

这是示例模型构建器方法:

Here is a sample model builder method:

        protected override void OnModelCreating(ModelBuilder modelBuilder)
             {
              modelBuilder.Entity<Address>(entity =>
                 {

                  entity.Property(e => e.AddressEmail)
                .IsRequired()
                .HasMaxLength(255)
                .IsUnicode(false)
                .HasDefaultValueSql("('')");

使用我的上下文，我可以找到最大长度，如下所示:

Using my context, I can find the maximum length like this:

  dbContext.Model.FindEntityType(typeof(Address)).FindProperty("AddressEmail").GetMaxLength()

使用Fluent验证，我可以这样做:

Using Fluent Validation, I can do this:

  RuleFor(Address => Address.AddressEmail).NotNull().MaximumLength(255);

这可行，但是，当我更改数据库结构时，我必须更新验证器.

So that works but, when I change the database structure, I have to update my validators.

我试图找出如何从实体框架MaxLength属性驱动我的Fluent Validation规则

I'm trying to figure out how to drive my Fluent Validation rules from the entity framework MaxLength property

任何帮助将不胜感激.

****引入dbcontext的部分工作方式，但我仍在努力获取规则:

**** Partially working way of bringing the dbcontext in but I still am struggling getting the rule:

 public AddressValidator(DbContext dbContext)
      {
        Microsoft.EntityFrameworkCore.Metadata.IEntityType et = dbContext.Model.FindEntityType(typeof(Address));

        foreach (var Property in et.GetProperties())
        {
            var maxLength = Property.GetMaxLength();
  ---->>>>> RuleFor(x =>x.{PropertyName})    Invalid but this is the idea
        }

推荐答案

您可以使用之前提供的代码将db上下文注入到验证器中.不确定是否有适配器可以自动执行

You can inject your db context into validator using the code you provided before. Not sure if there is an adapter that does it automatically

class MyClassValidator : AbstractValidator<MyClass>
{
    public MyClassValidator(MyDbContext dbContext)
    {
        var maxLength = dbContext.Model.FindEntityType(typeof(MyClass))
            .FindProperty(nameof(MyClass.Data)).GetMaxLength();

        RuleFor(x => x.Data)
            .MaximumLength(maxLength.Value);
    }
}

更新

使用表达式的版本

class MyClassValidator : AbstractValidator<MyClass>
{
    public MyClassValidator(MyDbContext dbContext)
    {
        var entityType = dbContext.Model.FindEntityType(typeof(MyClass));

        foreach (var property in typeof(MyClass).GetProperties()
            .Where(x => x.PropertyType == typeof(string)))
        {
            var maxLength = entityType
                .FindProperty(property.Name)
                .GetMaxLength();

            if (maxLength.HasValue)
            {
                var parameter = Expression.Parameter(typeof(MyClass));
                var memberExpression = Expression.Property(parameter, property.Name);
                var lambdaExpression = Expression.Lambda<Func<MyClass, string>>(memberExpression, parameter);

                RuleFor(lambdaExpression)
                    .MaximumLength(maxLength.Value);
            }
        }

    }
}

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