使用ADO.NET实体框架截取实体保存 [英] Intercept entity saving with ADO.NET Entities Framework

问题描述

我想使用ObjectContext＃SaveChanges（）存储之前，在实体对象内调用验证函数。现在，我可以自己跟踪所有改变的对象，然后循环遍历所有的对象，并调用它们的验证方法，但是我认为一个更简单的方法是在保存每个实体之前实现ObjectContext调用的一些回调。后者可以完成吗？有没有其他选择？

I want to invoke a validation function inside the entities objects right before they are stored with ObjectContext#SaveChanges(). Now, I can keep track of all changed objects myself and then loop through all of them and invoke their validation methods, but I suppose an easier approach would be implement some callback that ObjectContext will invoke before saving each entity. Can the latter be done at all? Is there any alternative?

推荐答案

我已经弄明白了。基本上我们可以拦截ObjectContext的SavingChanges事件，并循环遍历新添加/修改的实体来调用它们的验证功能。这是我使用的代码。

I've figured out how. Basically, we can intercept SavingChanges event of ObjectContext and loop through the newly added/modified entities to invoke their validation function. Here's the code I used.

    partial void OnContextCreated()
    {
        SavingChanges += PerformValidation;
    }

    void PerformValidation(object sender, System.EventArgs e)
    {
        var objStateEntries = ObjectStateManager.GetObjectStateEntries(
            EntityState.Added | EntityState.Modified);

        var violatedRules = new List<RuleViolation>();
        foreach (ObjectStateEntry entry in objStateEntries)
        {
            var entity = entry.Entity as IRuleValidator;
            if (entity != null)
                violatedRules.AddRange(entity.Validate());
        }
        if (violatedRules.Count > 0)
            throw new ValidationException(violatedRules);
    }

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