RavenDB：如何从 MultiMapIndex 中正确 query/filter 嵌套值？

Question

我的应用程序有一个要求，即应该能够 filter/search for Pairs by the Number of the related Contact。

A Pair 总是有对存储的 Contact 的引用，但联系人的号码没有，也不会存储在引用中。所以我尝试为此创建一个自定义索引，因为 Pair 和 Contact 存储在不同的集合中。

索引的简化示例如下所示。

public class Pairs_Search : AbstractMultiMapIndexCreationTask<Pairs_Search.Result>
{
    public class Result
    {
        public string Id { get; set; }
        public string Workspace { get; set; }
        public ContactResult Contact { get; set; }
        public bool HasContactDetails { get; set; }
    }

    public class ContactResult
    {
        public string Id { get; set; }
        public string Name { get; set; }
        public int Number { get; set; }
    }

    public Pairs_Search()
    {
        AddMap<Pair>(pairs => pairs
            .Select(p => new
                {
                    p.Id,
                    p.Workspace,
                    Contact = new
                    {
                        p.Contact.Id,
                        p.Contact.Name,
                        Number = 0
                    },
                    // Mark this items as WITHOUT contact details.
                    HasContactDetails = false,
                }
            )
        );

        AddMap<Contact>(contacts => contacts
            .Select(c => new
                {
                    Id = (string) null,
                    Workspace = (string) null,
                    Contact = new
                    {
                        c.Id,
                        Name = c.DisplayName,
                        c.Number
                    },
                    // Mark this items as WITH contact details.
                    HasContactDetails = true,
                }
            )
        );

        Reduce = results => results
            // First group by the contact ID. This will
            // create a group with 2 or more items. One with the contact
            // details, and one or more with pair details.
            // They are all marked by a boolean flag 'HasContactDetails'.
            .GroupBy(x => x.Contact.Id)
            // We are going to enrich each item in the current group, that is
            // marked as 'HasContactDetails = false', with the contact number.
            // We need that so that we can filter on it later.
            .Select(group =>
                group
                    .Select(i => new
                        {
                            i.Id,
                            i.Workspace,
                            Contact = new
                            {
                                i.Contact.Id,
                                i.Contact.Name,
                                // Does the current item have the contact details?
                                Number = i.HasContactDetails
                                    // Yes, in this case we use the previously set contact number.
                                    ? i.Contact.Number
                                    // No, find the item with the contact details and grab the number.
                                    : group.Single(x => x.HasContactDetails).Contact.Number
                            },
                            // Pass on the flag that indicates wheter or not
                            // this item has the contact details. We are going
                            // to need it later.
                            i.HasContactDetails
                        }
                    )
                    // We don't need the items with the contact details
                    // anymore, so filter them out.
                    .Where(x => !x.HasContactDetails)
            )
            // Flatten all the small lists to one big list.
            .SelectMany(x => x);

        // Mark the following fields of the result as searchable.
        Index(x => x.Contact.Number, FieldIndexing.Search);
    }
}

我已经设置了一个完整的示例来重现我遇到的问题。您可以找到示例 here.

创建索引工作正常。查询索引也能正常工作，因为它正确地匹配了配对和联系人，并用联系人的号码丰富了索引结果。但是当我尝试在嵌套的 Number 属性上使用 .Where() 或 .Search() 时，它无法从索引中正确过滤结果数据集。

如您在下面的代码示例中所见（在完整示例中也可用），没有任何过滤的索引有效。

private static async Task ThisOneWorks()
{
    using (var session = Store.OpenAsyncSession())
    {
        var results = await session
            .Query<Pairs_Search.Result, Pairs_Search>()
            .ToListAsync(); 

        LogResults("ThisOneWorks()", results);              
    }

    // Output:
    // ThisOneWorks(): Pair 'Harry Potter' with number '70'
    // ThisOneWorks(): Pair 'Harry Potter' with number '70'
    // ThisOneWorks(): Pair 'Hermione Granger' with number '71'
    // ThisOneWorks(): Pair 'Albus Dumbledore' with number '72'
}

过滤非嵌套值也有效（在完整示例中也可用）。如您所见，它过滤掉了具有不同工作区的那个。

private static async Task ThisOneWithWorkspaceFilterWorks()
{
    using (var session = Store.OpenAsyncSession())
    {
        var results = await session                 
            .Query<Pairs_Search.Result, Pairs_Search>()
            .Where(x => x.Workspace == "hogwarts")
            .ToListAsync(); 

        LogResults("ThisOneWithWorkspaceFilterWorks()", results);               
    }

    // Output:
    // ThisOneWithWorkspaceFilterWorks(): Pair 'Harry Potter' with number '70'
    // ThisOneWithWorkspaceFilterWorks(): Pair 'Harry Potter' with number '70'
    // ThisOneWithWorkspaceFilterWorks(): Pair 'Hermione Granger' with number '71'
}

当我在 Workspace 和 Number 属性上尝试 filter/search 时，我希望得到两个与联系人哈利·波特相关的结果。但是我只是得到一个空的数据集。

private static async Task ThisOneWithWorkspaceAndNumberFilterDoesntWork()
{
    using (var session = Store.OpenAsyncSession())
    {
        var results = await session                 
            .Query<Pairs_Search.Result, Pairs_Search>()
            .Where(x => x.Workspace == "hogwarts")
            .Where(x => x.Contact.Number == 70)
            .ToListAsync(); 

        LogResults("ThisOneWithWorkspaceAndNumberFilterDoesntWork()", results);             
    }

    // Output:
    // ThisOneWithWorkspaceAndNumberFilterDoesntWork(): EMPTY RESULTS!
}

谁能告诉我我做错了什么？任何帮助将不胜感激！

Answer 1

解决方法是将 ContactResult 存储在不同的集合中，
在这种情况下，这就是所谓的相关文件t，
当您创建索引时，您将“索引相关文档”

学习中的演示示例：
https://demo.ravendb.net/demos/csharp/related-documents/index-related-documents
该示例针对基本地图索引，但原理与多地图相同。

从索引 class 中删除 public class ContactResult 并用类似的东西定义索引：

         select new Result
        {
            ....
            Number = LoadDocument<Contact>(Pair.Contact).Number
            .... 
        }

RavenDB：如何从 MultiMapIndex 中正确 query/filter 嵌套值？

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