RavenDb: Find movies that Actor X is NOT acting in - ravendb

I'm new to RavenDb and I've encountered the following problem, which is pretty easy to solve in SQL databases, but not so easy in RavenDb (it seems).
Given my classes:
//document collection
public class Movie
{
public string Id { get; set; }
public string Title { get; set; }
public List<MovieActor> Actors { get; set; }
}
public class MovieActor
{
public string ActorId { get; set; }
public string CharacterName { get; set; }
public DateTime FirstAppearance { get; set; }
}
//document collection
public class Actor
{
public string Id { get; set; }
public string Name { get; set; }
}
Finding every movie that Leonardo DiCaprio is acting in is very easy and efficient with the following Map index:
public class Movies_ByActor : AbstractIndexCreationTask<Movie>
{
public Movies_ByActor()
{
Map = movies => from movie in movies
from actor in movie.Actors
select new
{
MovieId = movie.Id,
ActorId = actor.ActorId
};
}
}
But this is not what I want to achieve, I want the opposite... to find all the movies where Leonardo DiCaprio is not acting.
I have also tried the following query:
var leonardoActorId = "actor/1";
var movies = from movie in RavenSession.Query<Movie>()
where !movie.Actors.Any(a => a.ActorId.Equals(leonardoActorId))
select movie;
But this will only give me an exception:
System.InvalidOperationException: Cannot process negated Any(), see RavenDB-732 http://issues.hibernatingrhinos.com/issue/RavenDB-732
Anyone know how to achieve this the proper way in RavenDb ?

Using the method described in my blog post here:
http://www.philliphaydon.com/2012/01/18/ravendb-searching-across-multiple-properties/
You can create an index with an array of ActorIds:
public class Movies_ByActor : AbstractIndexCreationTask<Movie>
{
public Movies_ByActor()
{
Map = movies => from s in movies
select new
{
Actors = s.Actors.Select(x => x.ActorId)
};
}
public class ActorsInMovie
{
public object[] Actors { get; set; }
}
}
Then you can search where the movie doesn't contain the actor you want:
var result = session.Query<Movies_ByActor.ActorsInMovie, Movies_ByActor>()
.Where(x => x.Actors != (object)"actors/1")
.As<Movie>();
Since the object we're querying against is different to the result, we need to specify As<T> to tell RavenDB what the type of the object actually returned is.
Working sample: http://pastie.org/7092908

Related

Entity Framework dbcontext crashing during foreach loop

I have an asp.net core mvc project. I'm trying to get over 300+ records from a table(s) using entity framework. Here are the models I have:
public partial class Movies
{
public int Id { get; set; }
public string Title { get; set; }
public virtual MovieInfoes MovieInfoes { get; set; }
}
public partial class MovieInfoes
{
public int Id { get; set; }
public string Actors { get; set; }
public string Director { get; set; }
public virtual Movies IdNavigation { get; set; }
}
In the controller section, I have an action that is suppose to list the title, actors, and director data.
public IActionResult ListAllMovies()
{
var movies = context.Movies.Include("MovieInfoes").ToList();
foreach (var movie in movies)
{
string x = movie.MovieInfoes.Actors;
}
return View(movies);
}
For some reason, it is crashing after it iterates 19 records (I'm trying to iterate thru 300+ records). I get an error saying "NullReferenceException: Object reference not set to an instance of an object".
Note: I've tried with lazy loading and eager loading, and both ways result in same error.
You're likely attempting to access movie.MovieInfoes.Actors with an instance of movie that has a null MovieInfoes reference.
Try accessing Actors with a null-conditional operator by changing string x = movie.MovieInfoes.Actors; to string x = movie?.MovieInfoes?.Actors;

Query entries by nested collection elements in RavenDB

I'm new to RavenDB and I'm struggling with this simple (i guess) issue.
I have a Subscriber with a collection of Subscriptions. And I want to make search by Subscription's fields, and return related Subscriber.
Here are simplified class examples:
public class Subscriber
{
public string Email { get; set; }
public string Name { get; set; }
public string Phone { get; set; }
public List<Subscription> Subscriptions { get; set; }
}
public class Subscription
{
public Guid Id { get; set; }
public string EventType { get; set; }
}
I've tried to make an index, as it is said in RavenDB docs:
public class Subscriber_BySubscription : AbstractIndexCreationTask<Subscriber>
{
public Subscriber_BySubscription()
{
Map = subscribers => from subscriber in subscribers
from subscription in subscriber.Subscriptions
select new
{
subscription.EventType,
subscription.QueueName
};
}
}
But I'm not sure that this is what I need, since query by collection using Select and Contains doesn't work. Moreover, the code looks so ugly that I feel that this is not the way how it should be.
So, I'd like to query Subscriptions by EventType, and have corresponding Subscriber as a result. In LINQ it would look like this: subscribers.Where(x => x.Subscriptions.Select(c => c.EventType).Contains(myEventType))
Managed to do it. Here is the right index:
public class Subscriber_BySubscription : AbstractIndexCreationTask<Subscriber>
{
public class Result
{
public string EventType { get; set; }
}
public Subscriber_BySubscription()
{
Map = subscribers => from subscriber in subscribers
from subscription in subscriber.Subscriptions
select new
{
subscription.EventType
};
}
}
And that's how it should be used:
var results = uow.Session
.Query<Subscriber_BySubscription.Result, Subscriber_BySubscription>()
.Where(x => x.EventType == eventType)
.OfType<Subscriber>()
.ToList();

RavenDb Select() downcasts instead of selecting the neccessary fields

public class PersonBrief
{
public int Id { get; set; }
public string Picture { get; set; }
public PersonBrief(Person person)
{
Id = person.Id;
Picture = person.Picture;
}
}
public class Person : PersonBrief
{
public string FullName { get; set; }
}
var results = session.Query<Person>()
.Select(x => new PersonBrief(x))
.ToList();
Assert.IsNull(results[0] as Person); // Fails
Is this a bug? If not, what would be the correct way to select only the fields i'm interested in?
It would work if you move the .ToList before the .Select, but that would be doing the work on the client.
If you want to do it on the server, you need to use As in your query, and you need a static index that does a TransformResults. See these docs.

How to use Raven LoadDocument

I'm having trouble querying RavenDB with even the simplest of queries, probably I'm doing something wrong, but after a few hours I just can't see it anymore. I've googled almost anything I can think of..
I have these entities:
public class User
{
public string Id { get; set; }
public string DisplayName { get; set; }
public string RealName { get; set; }
public string Email { get; set; }
public string PictureUri { get; set; }
public List<Comment> Comments { get; set; }
public List<Role> Roles { get; set; }
}
public class NewsItem
{
public string Id { get; set; }
public string Title { get; set; }
public string Text { get; set; }
public DateTime Created { get; set; }
public string UserId { get; set; }
public List<Tag> Tags { get; set; }
public List<Comment> Comments { get; set; }
public List<WebImage> Images { get; set; }
}
I want to query these so I get a list of newsItems, but with the user information alongside it. So I read the docs and tried the LoadDocument feature, the index:
public class NewsItemIndexWithComments : AbstractIndexCreationTask<NewsItem, NewsItemIndexWithComments.Result>
{
public class Result
{
public string AuthorName { get; set; }
}
public NewsItemIndexWithComments()
{
Map = newsItems => from newsItem in newsItems
select new
{
AuthorName = LoadDocument<User>(newsItem.UserId).DisplayName
};
}
}
Which I try to use like:
var result = _documentSession.Query<NewsItemIndexWithComments.Result, NewsItemIndexWithComments>().AsProjection<NewsItemIndexWithComments.Result>().ToList();
Now I get the number of documents in my list, but the AuthorName is always null. If I don't use the AsProjection method, I won't get any results. Can anyone show me a proper example on which I can experiment further?
Thanks.
_ edit:
That helped a lot, thanks :) Now for step two, I'm sorry if I'm being a bit newbish, but you'll have to start somewhere. In the newsitems there are comments, in these comments there is another reference to the userid. You can probably guess what I want to do: I want the user info for the comments with the comments as well.
new Index:
public class NewsItemIndexWithComments : AbstractIndexCreationTask<NewsItem, NewsItemIndexWithComments.Result>
{
public class Result : NewsItem
{
public string AuthorName { get; set; }
public string AuthorId { get; set; }
}
public NewsItemIndexWithComments()
{
Map = newsItems => from newsItem in newsItems
let user = LoadDocument<User>(newsItem.UserId)
select new
{
AuthorName = user.DisplayName,
AuthorId = user.Id,
};
Store(x => x.AuthorName, FieldStorage.Yes);
Store(x => x.AuthorId, FieldStorage.Yes);
}
}
Comment class:
public class Comment
{
public string Id { get; set; }
public string Text { get; set; }
public string UserId { get; set; }
public string User { get; set; }
public DateTime Created { get; set; }
}
How can I query the comments and expand the results for that? Or is it better to create a new index just for the comments and get the user info analog to the solution above?
You're almost there, you just need to store the field you are projecting. Add this to the index constructor, after the map.
Store(x=> x.AuthorName, FieldStorage.Yes);
This is because you want it returned and available for AsProjection to find. If you just wanted to use the author name in a where or orderby, you wouldn't need it.
If you just want to include the comments in your AsProjection, you can simply index the entire object along.
Note that indexing a custom object will mean that you're not able to query on it using a .Where(). RavenDB can only query on flattened results (ints, decimals, strings, dates).
In order to, for instance, query on the title, you will need to create a seperate Property public string Title { get; set; } and map it with Title = newsItem.Title.
public class NewsItemIndexWithComments : AbstractIndexCreationTask<NewsItem, NewsItemIndexWithComments.Result>
{
public class Result : NewsItem
{
public string AuthorName { get; set; }
public string AuthorId { get; set; }
public List<Comment> Comments { get; set; }
}
public NewsItemIndexWithComments()
{
Map = newsItems => from newsItem in newsItems
let user = LoadDocument<User>(newsItem.UserId)
select new
{
AuthorName = user.DisplayName,
AuthorId = user.Id,
Comments = newsItem.Comments.
};
Store(x => x.AuthorName, FieldStorage.Yes);
Store(x => x.AuthorId, FieldStorage.Yes);
Store(x => x.Comments, FieldStorage.Yes);
}
}

RavenDB TransformResults

I'm trying to use the TransformResults feature, and I can't get it to work. I'm not totally sure I understand this feature, perhaps there is another way to solve this problem. What I want is just the Id from the Order and the email addesses from the Customer and the Entrepreneur. I am happy for all tips that can take me in the right direction. Here is my code.
Document
public class OrderDocument
public string Id {get; set }
public EntrepreneurInfo EntrepreneurInfo { get; set; }
public CustomerInfo CustomerInfo { get; set; }
public OrderStatus CurrentOrderStatus { get; set; }
}
Info classes
public class EntrepreneurInfo
{
public string EntrepreneurDocumentId { get; set; }
public string Number { get; set; }
public string Name { get; set; }
}
public class CustomerInfo
{
public string CustomerDocumentId { get; set; }
public string Number { get; set; }
public string Name { get; set; }
}
The info classes are just subsets of a Customer and Entrepreneur documents respectively.
The Customer and Entrepreneur documents inherits from a base class ( AbstractOrganizationDocument) that has the EmailAddress property.
My Index
public class OrdersApprovedBroadcastingData :
AbstractIndexCreationTask<OrderDocument, OrdersApprovedBroadcastingData.ReduceResult>
{
public OrdersApprovedBroadcastingData()
{
this.Map = docs => from d in docs
where d.CurrentOrderStatus == OrderStatus.Approved
select new
{
Id = d.Id,
CustomerId = d.CustomerInfo.CustomerDocumentId,
EntrepreneurId = d.EntrepreneurInfo.EntrepreneurDocumentId
};
this.TransformResults = (db, orders) => from o in orders
let customer = db.Load<CustomerDocument>(o.CustomerId)
let entrepreneur = db.Load<EntrepreneurDocument>(o.EntrepreneurId)
select
new
{
o.Id,
o.CustomerId,
CustomerEmail = customer.EmailAddress,
o.EntrepreneurId,
EntrepreneurEmail = entrepreneur.EmailAddress
};
}
public class ReduceResult
{
public string Id { get; set; }
public string CustomerId { get; set; }
public string CustomerEmail { get; set; }
public string EntrepreneurId { get; set; }
public string EntrepreneurEmail { get; set; }
}
}
If I look at the result of this Index in Raven Studio I get null values for all fields except the Id. And finally here is my query.
Query
var items =
this.documentSession.Query<OrdersApprovedBroadcastingData.ReduceResult, OrdersApprovedBroadcastingData>()
.Select(x => new OrdersToBroadcastListItem
{
Id = x.Id,
CustomerEmailAddress = x.CustomerEmail,
EntrepreneurEmailAddress = x.EntrepreneurEmail
}).ToList();
Change your index to:
public class OrdersApprovedBroadcastingData : AbstractIndexCreationTask<OrderDocument>
{
public OrdersApprovedBroadcastingData()
{
Map = docs => from d in docs
where d.CurrentOrderStatus == OrderStatus.Approved
select new
{
};
TransformResults = (db, orders) =>
from o in orders
let customer = db.Load<CustomerDocument>(o.CustomerInfo.CustomerDocumentId)
let entrepreneur = db.Load<EntrepreneurDocument>(o.EntrepreneurInfo.EntrepreneurDocumentId)
select new
{
o.Id,
CustomerEmailAddress = customer.EmailAddress,
EntrepreneurEmailAddress = entrepreneur.EmailAddress
};
}
}
Your result class can simply be the final form of the projection, you don't need the intermediate step:
public class Result
{
public string Id { get; set; }
public string CustomerEmailAddress { get; set; }
public string EntrepreneurEmailAddress { get; set; }
}
You don't have to nest this class in the index if you don't want to. It doesn't matter either way. You can query either with:
var items = session.Query<Result, OrdersApprovedBroadcastingData>();
Or with
var items = session.Query<OrderDocument, OrdersApprovedBroadcastingData>().As<Result>();
Though, with the first way, the convention tends to be to nest the result class, so really it would be
var items = session.Query<OrderDocument.Result, OrdersApprovedBroadcastingData>();
Note in the index map, I am not including any properties at all. None are required for what you asked. However, if you want to add a Where or OrderBy clause to your query, any fields you might want to filter or sort on should be put in there.
One last thing - the convention you're using of OrderDocument, CustomerDocument, EntrepreneurDocument, is a bit strange. The usual convention is just Order, Customer, Entrepreneur. Think of your documents as the persisted form of the entities themselves. The convention you are using will work, it's just not the one usually used.