I'm using NHibernate 3.33 and QueryOver with Postgre 9.2.
I've got two entities:
public class User {
public virtual string Name { get; set; }
public virtual IList<Reports> Reports { get; set; }
}
and
public class Report {
public virtual string Type { get; set; }
public virtual DateTime ReportDate { get; set; }
public virtual User Author { get; set; }
}
with association - one-to-many (I didn't append additional fields to entities like Id or Name to snippets above). Some report's types are avaliable - month, day.
My goal is to get summary for user - find out whether user has day-report and month-report for current day.
Note: month-report's ReportDate looks like first day of month. Also I want to get it as one row (if it was an SQL) to transform to dto:
public class UserSummaryDto {
public bool HasDayReport { get; set; }
public bool HasMonthReport { get; set; }
}
To achieve my goal I've tried following:
Report dayReport = null;
Report monthReport = null;
var currentDay; // some value of current day
var firstDay; // some value of first day of month
var report = session.QueryOver<User>
.Left.JoinAlias(u => u.Reports, () => dayReport, r => r.ReportDate == currentDay)
.Left.JoinAlias(u => u.Reports, () => monthReport, r => r.ReportDate == firstDat)
.SelectList(
// some logic to check whether user has reports
.TransformUsing(Transformers.AliasToBean<UserSummaryDto>())
.List<UserSummaryDto>()
And I've got error:
'duplicate association path:Reports'.
Is it possible to avoid this problem or it's a limitation of HNibernate?
To answer your question:
...Is it possible to avoid this problem or it's a limitation of HNibernate?
Have to say NO.
For more information see similar Q & A: Rename NHibernate criteria
We are not querying the DB, not using SQL (which does allow to do a lot). Here we work with "mapped" domain model, and that could bring some limitations - as the one discussed here...
If that could help, the workaround is to map such property twice and use the WHERE clause: 6.2. Mapping a Collection
where="" (optional) specify an arbitrary SQL WHERE condition to be used when retrieving or removing the collection (useful if the collection should contain only a subset of the available data)
Related
I am trying to create a static index for the following sample class:
public class Board {
...other assorted fields
List<dynamic> Messages {get; set;}
internal Board() {Messages = new List<dynamic>();}
}
The index is to filter boards which have messages which are a older than a certain date. The aim is to perform an "update" operation on messages which are due today, update their content, and persist them back. The index is needed to avoid traversing all the messages for a board for all clients as that may be computationally expensive. Messages is a list of message types which inherit from a base class which contains a property ExpiryDate.
Trying to create an index like follows results in an "An expression tree may not contain a
dynamic operation" error. I know that the dynamic type does not play well with Linq queries hence the need to use LuceneQueries instead of Query() in RavenDB. Is there any way to make this index work with dynamic properties? Thanks!
public class ScanBoardMessagesIndex : AbstractIndexCreationTask<Board>
{
public ScanBoardMessagesIndex () {
Map = boards => from board in boards
where board.Messages.Any(msg => ((MessageItem) msg).ExpiryDate <= DateTime.UtcNow.Date)
select board;
}
}
EDIT:
I ran into a raven serialization issue because the metadata clr-type of existing Board documents was set to a class namespace which was not valid anymore. I am doing a migration project so I went ahead and first issued a patch to change the metadata clr-type of the existing documents before migrating them to the new data structure which uses a base/abstract class for list of Messages instead of type dynamic.
A Map/Reduce index seems more appropriate for the given requirements. Effectively, you want to be able to query boards by the oldest expiry date of messages in the board. This is an aggregating operation, exactly what Map/Reduce was designed to solve. Also, using a base class for messages will allow you to define the index without resorting to the lower level IndexDefinition:
public class Message
{
public DateTime ExpiryDate { get; set; }
}
public class Board
{
public string Id { get; set; }
public List<Message> Messages { get; set; }
}
public class OldestExpiryDateMessageInBoard : AbstractIndexCreationTask<Board, OldestExpiryDateMessageInBoard.Result>
{
class Result
{
public string BoardId { get; set; }
public DateTime OldestExpiryDate { get; set; }
}
public OldestExpiryDateMessageInBoard()
{
this.Map = boards => from board in boards
from message in board.Messages
select new
{
BoardId = board.Id,
OldestExpiryDate = message.ExpiryDate
};
this.Reduce = results => from result in results
group result by result.BoardId into g
select new
{
BoardId = g.Key,
OldestExpiryDate = g.Min(x => x.OldestExpiryDate)
};
}
}
You can then query this index with Lucene syntax.
Imagine a database table that looks like this:
create table [dbo].[user]
(
id int IDENTITY(1,1),
username varchar(50) NOT NULL,
firstname varchar(20) NOT NULL,
lastname varchar(30) NOT NULL,
currentid int NULL,
processedby varchar(50) NOT NULL,
processeddate varchar(50) NOT NULL
processedaction varchar(50) NOT NULL
)
What I want to do is to setup NHibernate to load it into my user object, but I only want the current version of the object "user" to be brought back. I know how to do a SQL select to do this on my own, and I feel as if there's something in nHibernate with the usage of triggers and event listeners, but can anyone tell me how to implement the nHibernate repository so I can:
{Repository}.GetCurrent(id) <- pass it any of the ids that are assigned to any of the historical or the current record, and get back the current object.
{Repository}.Save(user) <- I want to always insert the changes to a new row, and then update the old versions to link back to the new id.
Edit
So, there's some confusion here, and maybe I explained it wrong... What I'm trying to do is this, in regards to always getting the current record back...
Select uc.*
FROM User uo
JOIN User uc on uo.currentid=uc.id
WHERE uo.id==:id
But, I don't want to expose "CurrentID" to my object model, since it has no bearing on the rest of the system, IMHO. In the above SQL statement, uo is considered the "original" object set, and uc is considered the current object in the system.
Edit #2:
Looking at this as a possible solution.
http://ayende.com/blog/4196/append-only-models-with-nhibernate
I'm honestly being pigheaded, as I'm thinking about this backward. In this way of running a database, the autoincrementing field should be the version field, and the "id" field should be whatever the autoincrementer's value has at the time of the initial insert.
Answer:
I don't want to take #Firo's fury, and I'm not going to remove it from him, as he took me down the right path... what I wound up with was:
Created a base generic class with two types given
a. type of the object's "ID"
b. type of the object itself.
instantiate all classes.
create a generic interface IRepository class with a type of the object to store/retrieve.
create an abstract generic class with a type of the object to store/retrieve.
create a concrete implementation class for each type to store/retrieve.
inside of the create/update, the procedure looks like:
Type Commit(Type item)
{
var clone = item.DeepClone();
_Session.Evict(item);
clone.Id = 0;
clone.ProcessedDate = DateTime.Now;
if (clone.Action.HasValue)
{
if (clone.Action == ProcessedAction.Create)
clone.Action = ProcessedAction.Update;
}
else
{
clone.Action = ProcessedAction.Create;
}
clone.ProcessedBy = UserRepos.Where(u => u.Username == System.Threading.Thread.CurrentPrincipal.Identity.Name).First().Current;
var savedItem = (_Session.Merge(clone) as Type);
_Session.CreateQuery("UPDATE Type SET CurrentID = :newID where ID=:newID OR CurrentID=:oldID")
.SetParameter("newID", savedItem.Id)
.SetParameter("oldID", item.Id)
.ExecuteUpdate();
return savedItem;
}
In the delete method, we simply update the {object}.Action = ProcessedAction.Delete
I wanted to do this another way, but realizing we need to eventually do historical comparisons, we weren't able to ask nHibernate to filter the deleted objects, as the users will want to see that. We'll create a business facade to take care of the deleted records.
Again, much thanks to #Firo for his help with this.
So, with all that, I can finally do this:
var result = {Repository}.Where(obj => obj.Id == {objectID from caller}).FirstOrDefault();
if (result != null)
{
return result.Current;
}
else
{
return null;
}
and always get my current object back for any requesting ID. Hope it helps someone that is in my situation.
in mapping if you use FluentNHibernate
public UserMap : ClassMap<User>
{
public UserMap()
{
Where("id = currentid"); // always bring back the most recent
}
}
// in Userrepository
public void Update(User user)
{
var clone = user.Clone();
session.Evict(user); // to prevent flushing the changes
var newId = session.Save(clone);
session.CreateQuery("UPDATE User u SET u.currentid = :current") // <-- hql
.SetParameter("current", newId)
.ExecuteUpdate();
}
objectgraphs are a lot trickier with this simple code. I would then do one of the following:
use NHibernate.Envers to store auditing information for me
explicitly creating new entities in BL code
i once saw an append-only-model doing something like the following
// UserBase is there to ensure that all others referencing the User doesnt have to update because user properties changed
class UserBase
{
public virtual int Id { get; set; }
public virtual ICollection<PersonDetails> AllDetails { get; private set; }
public virtual PersonDetails CurrentDetails
{
get { return _currentDetauils; }
set { _currentDetauils = value; AllDetails.Add(value); }
}
// same as above
public virtual ICollection<ConfigDetails> AllConfigs { get; set; }
}
class Order
{
public virtual int Id { get; set; }
public virtual UserBase User { get; set; }
public virtual IList<OrderDetail> AllDetails { get; private set; }
public virtual IList<OrderDetail> ActiveDetails { get; private set; }
public virtual void Add(OrderDetail detail)
{
AllDetails.Add(detail);
ActiveDetails.Add(detail);
}
public virtual void Delete(OrderDetail detail)
{
detail.Active = false;
ActiveDetails.Remove(detail);
}
}
class OrderDetail
{
public virtual int Id { get; set; }
public virtual Order Parent { get; set; }
public virtual bool Active { get; set; }
}
class OrderMap : ClassMap<Order>
{
public OrderMap()
{
HasMany(o => o.AllDetails);
HasMany(o => o.ActiveDetails).Where("active=1");
}
}
// somewhere
public void UpdateTaxCharge(OrderDetail detail, TaxCharge charge)
{
var clone = detail.Clone();
clone.TaxCharge = charge;
detail.Order.Delete(detail);
detail.Order.Add(clone);
}
You can tell NHibernate what exactly SQL it should generate when persisting and loading an entity. For example you can tell NHibernate to use a stored procedure instead of a plain SQL statement. If this is an option for you I can farther elaborate my answer.
I'm developing a project using Silverlight 4 and Entity Framework 4 and I'm trying to auto-load the details (with conditions) associated with an entity when the client loads the EntityQuery.
So far, I've been able to put in place a solution, using the Include attribute, that returns all the details associated with the master entity. What I'm missing here is to be able to filter out the details based on some criteria.
As an example, here's what my entities look like:
Entity Movie
Id (int)
[Include]
MovieLocalizedInformations (EntityCollection<MovieLocalizedInformation>)
Entity MovieLocalizedInformation
Id (int)
Movie_Id (int)
LanguageCode (eg.: en)
Title
On my DomainService object, I expose the following method:
public IQueryable<Movie> GetMovies( string languageCode )
{
return this.ObjectContext.Movies.Include( "MovieLocalizedInformations" );
}
This works fine. But when I try to add where clause to filter out the localized information based on the language code, only the movies get loaded on the client.
Is there a way to achieve the filtering in one query?
Note: I'm also using the DomainDataSource with paging on the client so the solution needs to work with that.
Any help would be greatly appreciated!
Thanks,
Jacques.
Not sure about Enitity Framework but with a LinqToSqlDomainService you use the LoadWith loadOption
to include the details entities and then use the AssociateWith LoadOption to filter the detail e.g
DataLoadOptions options = new DataLoadOptions();
options.LoadWith<Movies>(i => i.MovieLocalizedInformations);
options.AssociateWith<Movies>(i => i.MovieLocalizedInformations.Where(d=> myListOfIds.Contains(d.LocationId)));
Ok,
For efficiency reason, I decided to go with custom DTO object that fetches the localized information and flatten the result.
But, the same problem occurred when my custom DTO needed to reference another custom localized DTO.
Here is how I came to do the same as the .Include( "PropertyName" ) that the ObjectSet offers:
Entity LocalizedMovieCollection
public class LocalizedMovieCollection
{
[Key]
public int Id { get; set; }
public string Name { get; set; } (the result of a sub query based on the language)
[Include]
[Association( "LocalizedMovieCollection_LocalizedMovies", "Id", "MovieCollection_Id" )]
public IEnumerable<LocalizedMovie> Movies { get; set; }
}
Entity LocalizedMovie
public class LocalizedMovie
{
[Key]
public int Id { get; set; }
public string Name { get; set; } (the result of a sub query based on the language)
public int MovieCollection_Id { get; set; }
[Include]
[Association( "LocalizedMovie_LocalizedMovieCollection", "MovieCollection_Id", "Id", IsForeignKey = true]
public LocalizedMovieCollection MovieCollection { get; set; }
}
Then, I've declared two methods: One that returns an IQueryable of LocalizedMovieCollection and the other, an IQueryable of LocalizedMovie. (Note: There must be at least one method that returns each type of entity for the entity to get auto-generated on the Silverlight client)
My goal is to automatically load the MovieCollection associated with a Movie so the method definition to get the movies is as follow:
public IQueryable<LocalizedMovie> GetMovies( string languageCode )
{
return from movie in this.ObjectContext.Movies
join movieLocalizedInfo in this.ObjectContext.MovieLocalizedInformations
on movie equals movieLocalizedInfo.Movie
join movieCollection in this.ObjectContext.MovieCollections
on movie.MovieCollection equals movieCollection
join movieCollectionLocalizedInfo in this.ObjectContext.MovieCollectionLocalizedInformations
on movieCollection equals movieCollectionLocalizedInfo.MovieCollection
where movieLocalizedInfo.LanguageCode == languageCode && movieCollectionLocalizedInfo.LanguageCode == languageCode
select new LocalizedMovie()
{
Id = movie.Id,
Name = movieLocalizedInfo.Name
MovieCollection_Id = movieCollection.Id,
MovieCollection = new LocalizedMovieCollection(){ Id = movieCollection.Id, Name = movieCollectionLocalizedInfo.Name }
}
}
When the Silverlight client loads the query, all the LocalizedMovies and their associated LocalizedMovieCollections will be loaded into the context.
I want to select all requests that are outstanding for a given manager. A manager can have multiple teams.
I compose the queries applying various restrictions based upon permissions, and alter the queries to provide row counts, existence checks, sub queries, etc.
The composition makes use of QueryOver, though using ICriteria instead would also be acceptable.
Given the following classes;
class Team {
public virtual int Manager { get; set; }
public virtual ISet<int> Members { get; set; }
}
class Request {
public virtual int Owner { get; set; }
public virtual bool IsOutstanding { get; set; }
}
class static SomeRestrictions {
public static void TeamsForManager<TRoot> (this IQueryOver<TRoot, Team> query, int managerId) {
// In reality this is a little more complex
query.Where (x => x.Manager == managerId);
}
}
This is the current query that I'm trying (which doesn't work).
var users = QueryOver.Of<Team> ();
users.TeamsForManager (5)
users.Select (/* not sure */);
var requests = session.QueryOver<Request> ()
.Where (x => x.IsOutstanding)
.WithSubquery.WhereProperty (x => x.Owner).In (users);
The HQL to select the users would be:
"SELECT m FROM Team t JOIN t.Members m WHERE <TeamsForManager restrictions>"
But I don't want to use HQL because I can't then compose it with other restrictions based upon permissions. I also wouldn't be able to compose it with other queries to turn it into row counts/existence checks, etc.
i saw you changed the model but this would have been the way
var users = QueryOver.Of<Team> ();
users.TeamsForManager (5);
users.JoinAlias(t => t.Members, () => membervalue).Select(() => membervalue);
I have the following classes:
class Employee
{
public string Name { get; set; }
}
class HistoricalEmployee : Employee
{
public DateTime TerminationDate { get; set; }
}
class Company
{
public IList<Person> CurrentEmployees { get; set; }
}
Employee and HistoricalEmployee are mapped using table-per-class-heirarchy strategy.
When I retrieve the CurrentEmployees collection, I want it only to contain elements that are Employee, and NOT HistoricalEmployees.
when an employee 'dies', they're not really deleted, but they become HistoricalEmployee (with a few more attributes, such as termination date etc.).
Obviously, over time, the number of HistoricalEmployees will exceed the number of Employees by magnitudes, so I can't fetch all HistoricalEmployees when I only need current Employees.
How can I (fluently) configure the collection to only retrieve elements of the super class?
I think it's something to do with the Polymorphism property, but I couldn't really figure out how to do that.
thanks,
Jhonny
Ok, I did this like so:
mapping.HasMany(x => x.CurrentEmployees)
//.Where(pqa => pqa.TimeOut != null)
.Where("TerminationDate is null")
apparently, the .Where() function creates a filter on the property, which is exactly what I needed.
notice that I used the string version, and commented-out the Func<> version.
This is because that currently (FNH 1.1), as far as I could determine, the Func<> version doesn't work.
hopes this helps somebody,
J