Question

我非常是EF4的新手。我已经发布了几次关于继承，验证的帖子，但我的总体目标是尽可能减少我编写的代码量。我对POCO感兴趣，大量的ObjectContext摆弄：我想要EF的好处和最少的编码。

所以，棘手的验证问题。看看这个简化的例子，（除了DRY伙伴和狡猾的使用别名），这看起来像是一个不太合适的方法吗？

namespace Model
{
    using Microsoft.Practices.EnterpriseLibrary.Validation.Validators;
    using DataAnnotations = System.ComponentModel.DataAnnotations;
    using Validation = Microsoft.Practices.EnterpriseLibrary.Validation;

    [HasSelfValidation]
    [DataAnnotations.MetadataType(typeof(PersonValidator))]
    public partial class Person
    {
        [SelfValidation]
        public Validation.ValidationResults Validate()
        {
            var validationResults = Validation.Validation.Validate(this);

            if (string.IsNullOrEmpty(this.LastName) || this.LastName.Length > 4)
            {
                validationResults.AddResult(new Validation.ValidationResult("This is a test error message for a custom validation error.", this, null, null, null));
            }

            return validationResults;
        }
    }

    [HasSelfValidation]
    public class PersonValidator
    {
        [NotNullValidator(MessageTemplate = "First Name must be supplied.")]
        [ContainsCharactersValidator("Rcd", ContainsCharacters.All, MessageTemplate = "{1} must contains characters \"{3}\" ({4}).")]
        [StringLengthValidator(5, 50, MessageTemplate = "{1} (\"{0}\") must be between {3} ({4}) and {5} ({6}) characters in length.")]
        public string FirstName { get; set; }

        [NotNullValidator(MessageTemplate = "Last Name must be supplied.")]
        [ContainsCharactersValidator("Wes", ContainsCharacters.All, MessageTemplate = "{1} must contains characters \"{3}\" ({4}).")]
        [StringLengthValidator(5, 50, MessageTemplate = "{1} (\"{0}\") must be between {3} ({4}) and {5} ({6}) characters in length.")]
        public string LastName { get; set; }
    }
}

有一些相当酷的事情。我可以这样称呼以上内容：

var validationResults = person.Validate();

但是，如果我只想要一些基本的检查，我可以删除Validate（），[SelfValidation]的东西，保留属性，然后只需调用：

var validationResults = Validation.Validate(person);

我只需要包含尽可能多的验证，并且在web.config中有ZERO配置。

我的副臂怎么样？：）

理查德

Answer 1

我个人不是直接在代码中调用验证的粉丝，特别是不直接在实体本身。您会拨打Validate很多地方，很容易忘记致电Validate。相反，让ObjectContext自动为所有已更改的实体调用底层验证框架，并在发生验证错误时抛出一个特殊异常（可以在表示层中捕获）。

您可以通过挂钩ObjectContext.SavingChanges事件并在那里触发验证来完成此操作。您可以按如下方式编写部分ObjectContext：

public partial class ModelContainer
{
    partial void OnContextCreated()
    {
        this.SavingChanges +=
            (sender, e) => Validate(this.GetChangedEntities());
    }

    private IEnumerable<object> GetChangedEntities()
    {
        const EntityState AddedAndModified =
            EntityState.Added | EntityState.Modified;

        var entries = this.ObjectStateManager
            .GetObjectStateEntries(AddedAndModified);

        return entries.Where(e => e != null);
    }

    private static void Validate(IEnumerable<object> entities)
    {
        ValidationResults[] invalidResults = (
            from entity in entities
            let type = entity.GetType()
            let validator = ValidationFactory.CreateValidator(type)
            let results = validator.Validate(entity)
            where !results.IsValid
            select results).ToArray();

        if (invalidResults.Length > 0)
            throw new ValidationException(invalidResults);
    }    
}

您可以详细了解here。

验证此EF4验证方法？

1 个答案: