如何解决检查修改表达式
我们可以验证以下表达式是否可以在不执行用户ID的情况下对其进行修改吗?
Expression<Func<User,User>> expression = user => new User { Id = 2 };
Func<User,User> update = expression.Compile();
User userReferent = new User();
User userTransform = update(new User());
return userReferent.Id != userTransform.Id;
我们可以做类似下面的事情吗?
Expression<Func<User,User>> expression = user => new User { Id = 2 };
return expression.Contains(user => user.Id)
解决方法
我找到了解决方案。我可以检查表达式,而不必编译表达式。
Expression<Func<User,User>> expression = user => new User { TenantId = 2,Name = user.Name + "Test" };
Expression<Func<User,object>> searchMemberExpression = user => user.TenantId;
expression.Contains(searchMemberExpression) // return true
public static bool Contains<TEntity>(this Expression<Func<TEntity,TEntity>> expression,Expression<Func<TEntity,object>> searchExpression)
where TEntity : class
{
UnaryExpression unaryExpression = (UnaryExpression)searchExpression.Body;
MemberExpression memberExpression = (MemberExpression)unaryExpression.Operand;
MemberInitExpression memberInitExpression = (MemberInitExpression)expression.Body;
System.Collections.ObjectModel.ReadOnlyCollection<MemberBinding> bindings = memberInitExpression.Bindings;
bool result = bindings.Any(binding => binding.Member == memberExpression.Member);
return result;
}
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