无法使用 marten 和 Linq 查询子类型

如何解决无法使用 marten 和 Linq 查询子类型

我是 marten 的新手，对于应该很简单的查询遇到了严重的困难。我有一个 Person 类，它有一个类型为 EmailAddress 的属性。我想找到任何拥有特定电子邮件地址的人。

public class EmailAddress : ValueObject
{
    // construction
    protected EmailAddress() { } // needed for deserialization

    public EmailAddress(EmailType type,string emailAddress)
    {
        Guard.Against.Null(type,nameof(type));
        Guard.Against.NullOrWhiteSpace(emailAddress,nameof(emailAddress));
        Guard.Against.NotValidEmail(emailAddress,nameof(emailAddress));

        if (!(type.HasFlag(EmailType.Personal) || type.HasFlag(EmailType.Work) || type.HasFlag(EmailType.Other))) throw new ArgumentException("Unable to craete an EmailAddress without a valid type (i.e.,Personal,Work,Other).");

        Type = type;
        Address = emailAddress;
    }


    // properties
    public EmailType Type { get; private set; }
    public string Address { get; private set; }       
}


public class Person : ValueObject
{
    // fields
    List<EmailAddress> _emails = new List<EmailAddress>();

    // Construction
    protected Person() { } // needed for deserialization

    public Person(Guid id,string firstName,string lastName,EmailAddress identityAddress)
    {
        Guard.Against.Default(id,nameof(id));
        Guard.Against.NullOrWhiteSpace(firstName,nameof(firstName));
        Guard.Against.NullOrWhiteSpace(lastName,nameof(lastName));
        Guard.Against.Null(identityAddress,nameof(identityAddress));

        if (!identityAddress.Type.HasFlag(EmailType.IsIdentity))
        {
            identityAddress = new EmailAddress(identityAddress.Type | EmailType.IsIdentity,identityAddress.Address);
        }

        this.Id = id;
        this.FirstName = firstName;
        this.LastName = lastName;
        _emails.Add(identityAddress);
    }

    // properties        
    public Guid Id { get; private set; }
    public string FirstName { get; private set; }
    public string LastName { get; private set; }
    public IReadOnlyList<EmailAddress> Emails { get => _emails; }       
}

我创建了一个连接到 Postgresql 的测试类，并且能够使用 marten 插入类型。序列化器运行良好，能够使用它们的非公共 setter 序列化和反序列化这些类型。但是任何与 Person 类型的 Emails 属性相关的查询都会失败。

    [TestMethod]
    public void Can_Find_Person_Manual()
    {
        // set the test values
        Guid lukeId = Guid.NewGuid();
        EmailAddress lukeEmail = new EmailAddress(EmailType.Work | EmailType.IsIdentity,"[e-mail]");
        Person lukeSkywalker = new Person(lukeId,"Luke","Skywalker",lukeEmail);

        Guid leiaId = Guid.NewGuid();
        EmailAddress leiaEmail = new EmailAddress(EmailType.Personal | EmailType.IsIdentity,"[e-mail]");
        Person leiaSolo = new Person(leiaId,"Leia","Solo",leiaEmail);

        // add a test object
        IDocumentStore database = _container.GetInstance<IDocumentStore>();
        using (var session = database.LightweightSession())
        {
            // clear prior people
            session.DeleteWhere<Person>(p => true);
            session.SaveChanges();

            // Add new people
            session.Store<Person>(lukeSkywalker);
            session.Store<Person>(leiaSolo);
            session.SaveChanges();

            // Start Testing
            IReadOnlyList<Person> people = session.LoadMany<Person>(new Guid[] { lukeId,leiaId });
            Assert.IsTrue(people.Count == 2);

            Person luke = session.Load<Person>(lukeId);
            Assert.IsTrue(luke.Id == lukeId);
            Assert.IsTrue(luke.Emails.Contains(e => e.Address == "[e-mail]"));

            Person foundLuke = session.Query<Person>().Where(p => p.FirstName == "Luke").First();
            Assert.IsTrue(foundLuke.Id == lukeId);

            Person leia = session.Load<Person>(leiaId);
            Assert.IsTrue(leia.Id == leiaId);
            Assert.IsTrue(leia.Emails.Contains(e => e.Address == "[e-mail]"));


            List<Person> allPeople = session.Query<Person>().ToList(); // works fine 2 items

            List<Person> allLeias = session.Query<Person>().Where(p => p.FirstName == "Leia").ToList();  // works fine 1 item

            List<Person> allBills = session.Query<Person>().Where(p => p.FirstName == "Bill").ToList();  // works fine 0 items

            // List<Person> withEmail = session.Query<Person>().Where(p => p.Emails.Count > 0).ToList(); // ERROR returns empty list

            // List<Person> withEmail = session.Query<Person>().Where(p => p.Emails.Count(e => true) > 0).ToList(); // ERROR: select d.data,d.id,d.mt_version from public.mt_doc_person as d where jsonb_array_length(CAST(d.data ->> 'Emails' as jsonb)) > :arg0$ $ 22023: cannot get array length of a non - array' 

            List<Person> allLukes = session.Query<Person>().Where(p => p.Emails.Any(e => e.Address == "[e-mail]")).ToList();  // ERROR NullreferenceException

            //// should get Leia
            List<Person> withPersonalEmail = session.Query<Person>().Where(p => p.Emails.Any(e => e.Type == EmailType.Personal)).ToList(); // ERROR returns empty List

            List<Person> ranchEmail = session.Query<Person>().Where(p => p.Emails.Any(e => e.Address.Contains("ranch"))).ToList();  // ERROR 'Specific method not supported'

            // Below  is the one is need
            Person foundLeia = session.Query<Person>().Where(p => p.Emails.Any(_ => _.Address == "[e-mail]")).SingleOrDefault(); // ERROR returns null
            Assert.IsTrue(foundLeia.Id == leiaId);
        }
    }

解决方法

在我们的例子中，问题是我们的集合属性没有被序列化为 JSON 数组。

我们通过将 Json 序列化器的 CollectionStorage 属性设置为 CollectionStorage.AsArray，因此集合被序列化为 JSON 数组。

请参阅以下链接中的“集合存储”部分：https://martendb.io/documentation/documents/json/newtonsoft/

我们还需要将 TypeNameHandling 设置为 None，以防止在我们的集合被序列化并保存到数据库时存储类型元数据。 （有关详细信息，请参阅上述链接的介绍部分。）

var serialiser = new JsonNetSerializer
{
    CollectionStorage = CollectionStorage.AsArray,EnumStorage = EnumStorage.AsString
};

serialiser.Customize(x =>
{
    x.TypeNameHandling = TypeNameHandling.None;
});