eager-loading

I've been trying to familiarize myself with the Entity Framework. Most of it seems straight forward, but I'm a bit confused on the difference between eager loading with the Include method and default lazy loading. Both seem like they load related entities, so on the surface it looks like they do the same thing. What am I missing? Let's say you have two entities with a one-to-many relationship: Customer and Order, where each Customer can have multiple Orders. When loading up a Customer entity, Entity Framework allows you to either eager load or lazy load the Customer's Orders collection. If you

I think I need something akin to a rails eager loaded query with a limit on it but I am having trouble finding a solution for that. For the sake of simplicity, let us say that there will never be more than 30 Person s in the system (so Person.all is a small dataset) but each person will have upwards of 2000 comments (so Person.include(:comments) would be a large data set). Parent association class Person < ActiveRecord::Base has_many :comments end Child association class Comment < ActiveRecord::Base belongs_to :person end I need to query for a list of Person s and include their comments , but

In EF 4, can I do eager loading of navigation properties by writing sql on DbContext.Database.SqlQuery or DbContext.Set<T>().SqlQuery ? I don't seem to be getting my navigation properties populated. Edit It seems I can do eagerloading with DbContext.Set().SqlQuery, just not DbContext.Database.SqlQuery. Any idea why? DbSet.SqlQuery works differently than Database.SqlQuery. The method on DbSet applies to the given entity set. It has to return entities of the given type and by default the returned entities will be tracked. Database.SqlQuery can return any object (possibly not an entity) and the

Domain Model I've got a canonical Domain of a Customer with many Orders , with each Order having many OrderItems : Customer public class Customer { public Customer() { Orders = new HashSet<Order>(); } public virtual int Id {get;set;} public virtual ICollection<Order> Orders {get;set;} } Order public class Order { public Order() { Items = new HashSet<OrderItem>(); } public virtual int Id {get;set;} public virtual Customer Customer {get;set;} } OrderItems public class OrderItem { public virtual int Id {get;set;} public virtual Order Order {get;set;} } Problem Whether mapped with FluentNHibernate

I want to load root entities and eager load all it's child collection and aggregate members. Have been trying to use the SetFetchMode in FluentNHibernate, but I am getting duplicates in one of the child collection since I have a depth of 3 levels. DistinctRootEntityResultTransformer unfortunately only removes the root duplications. return Session.CreateInvoiceBaseCriteria(query, archived) .AddOrder(new Order(query.Order, query.OrderType == OrderType.ASC)) .SetFetchMode("States", FetchMode.Eager) .SetFetchMode("Attestations", FetchMode.Eager) .SetFetchMode("AttestationRequests", FetchMode.Eager

For example I have a blog object, and that blog has many posts. I want to do eager loading of say the first blog object and include say the first 10 posts of it. Currently I would do @blogs = Blog.limit(4) and then in the view use @blogs.posts.limit(10) . I am pretty sure there is a better way to do this via an include such as Blog.include(:posts).limit(:posts=>10) . Is it just not possible to limit the number of included objects, or am I missing something basic here? Looks like you can't apply a limit to :has_many when eager loading associations for multiple records. Example: class Blog <

I'm querying data with parent/child result sets using Entity Framework and I want to export this data to an XML document. var agreement = storeops.Agreements.SingleOrDefault(a => a.AgreementNumber == AgreementTextBox.Text); XmlSerializer serializer = new XmlSerializer(agreement.GetType()); XmlWriter writer = XmlWriter.Create("Agreement.xml"); serializer.Serialize(writer, agreement); This works well except it only serializes the parent without including the related child records in the XML. How can I get the children to serialize as well? I also tried using POCO generated code and the child