Search Results

Search found 19802 results on 793 pages for 'linq entity framework'.

Page 12/793 | < Previous Page | 8 9 10 11 12 13 14 15 16 17 18 19  | Next Page >

  • Linq to List and IEnumerable issues

    - by Otaku
    I am querying an HTML file with Linq. It looks something like this: <html> <body> <div class="Players"> <div class="role">Goalies</div> <div class="name">John Smith</div> <div class="name">Shawn Xie</div> <div class="role">Right Wings</div> <div class="name">Jack Davis</div> <div class="name">Carl Yuns</div> <div class="name">Wayne Gortonia</div> <div class="role">Centers</div> <div class="name">Lutz Gaspy</div> <div class="name">John Jacobs</div> </div </html> </body> What I'm trying to do is create a list of these folks like in a list of a structure called Players: Structure Players Public Name As String Public Position As String End Structure But I've quickly found out I don't really know what I'm doing when it comes to Linq. I've got this far my my queries: Dim goalieList = From d In player.Elements _ Where d.Value = "Goalies" _ Select From g In d.ElementsAfterSelf _ Take While (g.@class <> "role") _ Select New Players With {.Position = "Goalie", _ .Name = g.Value} Dim centersList = From d In player.Elements _ Where d.Value = "Centers" _ Select From g In d.ElementsAfterSelf _ Take While (g.@class <> "role") _ Select New Players With {.Position = "Centers", _ .Name = g.Value} Which gets me down to the the players by position, but then I can't do much with this afterwards the result type is System.Collections.Generic.IEnumerable(Of System.Collections.Generic.IEnumerable(Of Player)) What I want to do is add these two results to a new list, like: Dim playersList As List(Of Players) = Nothing playersList.AddRange(centersList) playersList.AddRange(goalieList) So that I can then query the list and use it. But it kicks the error: Unable to cast object of type 'WhereSelectEnumerableIterator2[System.Xml.Linq.XElement,System.Collections.Generic.IEnumerable1[Players]]' to type 'System.Collections.Generic.IEnumerable`1[Players]' As you can see, I may really have no idea how to work with all these objects/classes. Does anyone have any insight on what I may be doing wrong and how I can resolve it? RESOLVED: The Linq query needs to return a single iEnumerable, like this: Dim goalieList = From l In _ (From d In players.Elements _ Where d.Value = "Goalies" _ Select d.ElementsAfterSelf.TakeWhile(Function(f) f.@class <> "role")) _ Select New Players With {.Position = "Goalie", .Name = l.Value} and then use goalieList.ToList

    Read the article

  • How to do a "where in values" in LINQ-to-Entities

    - by Ty
    Does anybody know how to apply a "where in values" type condition using LINQ-to-Entities? I've tried the following but it doesn't work: var values = new[] { "String1", "String2" }; // some string values var foo = model.entitySet.Where(e = values.Contains(e.Name)); I believe this works in LINQ-to-SQL though? Any thoughts?

    Read the article

  • How to ignore blank elements in linq query

    - by Maestro1024
    How to ignore blank elements in linq query I have a linq query var usersInDatabase = from user in licenseUserTable where user.FirstName == first_name && user.LastName == last_name select user; But if I get here and first_name or last_name is blank then I want to still evaluate the other data item.

    Read the article

  • Linq to SQL Repository ~theory~ - Generic but now uses Linq to Objects?

    - by Matt Tolliday
    The project I am currently working on used Linq to SQL as an ORM data access technology. Its an MVC3 Web app. The problem I faced was primarily due to the inability to mock (for testing) the DataContext which gets autogenerated by the DBML designer. So to solve this issue (after much reading) I refactored the repository system which was in place - single repository with seperate and duplicated access methods for each table which ended up with something like 300 methods only 10 of which were unique - into a single repository with generic methods taking the table and returning more generic types to the upper reaches of the application. My question revolves more around the design I've used to get thus far and the differences I'm noticing in the structure of the app. 1) Having refactored the code from the dark ages which used classic Linq to SQL queries: public Billing GetBilling(int id) { var result = ( from bil in _bicDc.Billings where bil.BillingId == id select bil).SingleOrDefault(); return (result); } it now looks like: public T GetRecordWhere<T>(Expression<Func<T, bool>> predicate) where T : class { T result; try { result = _dataContext.GetTable<T>().Where(predicate).SingleOrDefault(); } catch (Exception ex) { throw ex; } return result; } and is used by the controller with a query along the lines of: _repository.GetRecordWhere<Billing>(x => x.BillingId == 1); which is fine, and precisely what I wanted to achieve. ...however.... I'm also having to do the following to get precisely the result set i require in the controller class (the highest point of the app in essence)... viewModel.RecentRequests = _model.GetAllRecordsWhere<Billing>(x => x.BillingId == 1) .Where(x => x.BillingId == Convert.ToInt32(BillingType.Submitted)) .OrderByDescending(x => x.DateCreated). Take(5).ToList(); This - as far as my understanding is correct - is now using Linq to Objects rather than the Linq to SQL queries I was previously? Is this okay practise? It feels wrong to me but I dont know why. Probably because the logic of the queries is in the very highest tier of the app, rather than the lowest, but... I defer to you good people for advice. One of the issues I considered was bringing the entire table into memory but I understand that using the Iqeryable return type the where clause is taken to the database and evaluated there. Thus returning only the resultset i require... i may be wrong. And if you've made it this far, well done. Thank you, and if you have any advice it is very much appreciated!!

    Read the article

  • Linq Query with aggregate function

    - by Billy Logan
    Hello everyone, I am trying to figure out how to go about writing a linq query to perform an aggregate like the sql query below: select d.ID, d.FIRST_NAME, d.LAST_NAME, count(s.id) as design_count from tbldesigner d inner join TBLDESIGN s on d.ID = s.DESIGNER_ID where s.COMPLETED = 1 and d.ACTIVE = 1 group by d.ID, d.FIRST_NAME, d.LAST_NAME Having COUNT(s.id) > 0 If this is even possible with a linq query could somebody please provide me with an example. Thanks in Advance, Billy

    Read the article

  • Implement LINQ to Entities unsupported method

    - by Dan
    Hi! LINQ to Entities has many LINQ methods marked as "Unsupported" (http://msdn.microsoft.com/en-us/library/bb738550.aspx). Is any way to implement some of these methods by hands? Or I should wait next release of EF? I'm especially needing this method: IQueryable<TResult> Select<TSource, TResult>(this IQueryable<TSource> source, Expression<Func<TSource, int, TResult>> selector) Thanks

    Read the article

  • OrderBy on children in a LINQ Query

    - by eka808
    Hello everybody I have a user entity who contains a one to many relationship with a role entity So with this linq expression : from user in USER_TABLE.Include("USERROLE_TABLE") order by user.Name select user I can get users with related roles as a child. My problem is that i want to get roles of each user ordered alphabetically. How can i do that ? I googled a lot and don't find anything Thank's by advance !

    Read the article

  • RC of Entity Framework 4.1 (which includes EF Code First)

    - by ScottGu
    Last week the data team shipped the Release Candidate of Entity Framework 4.1.  You can learn more about it and download it here. EF 4.1 includes the new “EF Code First” option that I’ve blogged about several times in the past.  EF Code First provides a really elegant and clean way to work with data, and enables you to do so without requiring a designer or XML mapping file.  Below are links to some tutorials I’ve written in the past about it: Code First Development with Entity Framework 4.x EF Code First: Custom Database Schema Mapping Using EF Code First with an Existing Database The above tutorials were written against the CTP4 release of EF Code First (and so some APIs might be a little different) – but the concepts and scenarios outlined in them are the same as with the RC. Go Live License Last week’s EF 4.1 RC ships with a “go live” license that enables you to use it in production environments.  The final release of EF 4.1 will ship within the next 4 weeks and will be 100% API compatible with the RC release. Improvements with the RC The RC includes several improvements and enhancements.  The EF team has a good blog post summarizing the RC changes.  Scott Hanselman also has a nice video interview with the data team that talks more about the release. One of my favorite improvements introduced with last week’s RC is its support for medium trust security.  This enables you to use EF 4.1 (and code-first) within low-cost ASP.NET shared hosting web environments – without requiring a hoster to install anything to use it. EF 4.1 also now supports validation with not only code-first scenarios, but also model-first and database-first workflows.  Upgrading from previous releases The RC does include a few API tweaks and changes from the prior CTP builds.  Read the release notes that come with the release to get a more detailed listing of the changes. John Papa also has an excellent Upgrading to EF 4.1 RC blog post that describes the steps he took when upgrading a large project he wrote with the previous CTP5 release.  The work to upgrade is pretty straight forward and easy – use his write-up as a guide on how to quickly update projects of your own. NuGet Package Rename One of the changes that the data team made between the CTP5 and RC releases was to rename the NuGet package name from “EFCodeFirst” to “EntityFramework”. They decided to make this change since the EF 4.1 release now includes several additions above and beyond just code first. If you already have installed the “EFCodeFirst” NuGet package, you’ll want to uninstall it and then install the new “EntityFramework” NuGet package.  John Papa’s blog post details the exact steps on how to do this (it only takes ~20 seconds to do this). More EF Tutorials Julie Lerman has created some nice whitepapers and tutorials for MSDN that show using the new EF4 and EF 4.1 feature set. Click here to find links to read and watch them. Summary I’m really excited about the EF 4.1 release that will be shipping next month.  It significantly improves the Entity Framework, and makes it even easier and cleaner to work with data inside of .NET.  You can take advantage of it within all ASP.NET projects (including both Web Forms and MVC), within client projects using Windows Forms and WPF, and within other project types like WCF, Console and Services.  You can use NuGet to easily install it within all of them. Hope this helps, Scott P.S. I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

    Read the article

  • Problem resolving a generic Repository with Entity Framework and Castle Windsor Container

    - by user368776
    Hi, im working in a generic repository implementarion with EF v4, the repository must be resolved by Windsor Container. First the interface public interface IRepository<T> { void Add(T entity); void Delete(T entity); T Find(int key) } Then a concrete class implements the interface public class Repository<T> : IRepository<T> where T: class { private IObjectSet<T> _objectSet; } So i need _objectSet to do stuff like this in the previous class public void Add(T entity) { _objectSet.AddObject(entity); } And now the problem, as you can see im using a EF interface like IObjectSet to do the work, but this type requires a constraint for the T generic type "where T: class". That constrait is causing an exception when Windsor tries to resolve its concrete type. Windsor configuration look like this. <castle> <components> <component id="LVRepository" service="Repository.Infraestructure.IRepository`1, Repository" type="Repository.Infraestructure.Repository`1, Repository" lifestyle="transient"> </component> </components> The container resolve code IRepository<Product> productsRep =_container.Resolve<IRepository<Product>>(); Now the exception im gettin System.ArgumentException: GenericArguments[0], 'T', on 'Repository.Infraestructure.Repository`1[T]' violates the constraint of type 'T'. ---> System.TypeLoadException: GenericArguments[0], 'T', on 'Repository.Infraestructure.Repository`1[T]' violates the constraint of type parameter 'T'. If i remove the constraint in the concrete class and the depedency on IObjectSet (if i dont do it get a compile error) everything works FINE, so i dont think is a container issue, but IObjectSet is a MUST in the implementation. Some help with this, please.

    Read the article

  • Changes to the LINQ-to-StreamInsight Dialect

    - by Roman Schindlauer
    In previous versions of StreamInsight (1.0 through 2.0), CepStream<> represents temporal streams of many varieties: Streams with ‘open’ inputs (e.g., those defined and composed over CepStream<T>.Create(string streamName) Streams with ‘partially bound’ inputs (e.g., those defined and composed over CepStream<T>.Create(Type adapterFactory, …)) Streams with fully bound inputs (e.g., those defined and composed over To*Stream – sequences or DQC) The stream may be embedded (where Server.Create is used) The stream may be remote (where Server.Connect is used) When adding support for new programming primitives in StreamInsight 2.1, we faced a choice: Add a fourth variety (use CepStream<> to represent streams that are bound the new programming model constructs), or introduce a separate type that represents temporal streams in the new user model. We opted for the latter. Introducing a new type has the effect of reducing the number of (confusing) runtime failures due to inappropriate uses of CepStream<> instances in the incorrect context. The new types are: IStreamable<>, which logically represents a temporal stream. IQStreamable<> : IStreamable<>, which represents a queryable temporal stream. Its relationship to IStreamable<> is analogous to the relationship of IQueryable<> to IEnumerable<>. The developer can compose temporal queries over remote stream sources using this type. The syntax of temporal queries composed over IQStreamable<> is mostly consistent with the syntax of our existing CepStream<>-based LINQ provider. However, we have taken the opportunity to refine certain aspects of the language surface. Differences are outlined below. Because 2.1 introduces new types to represent temporal queries, the changes outlined in this post do no impact existing StreamInsight applications using the existing types! SelectMany StreamInsight does not support the SelectMany operator in its usual form (which is analogous to SQL’s “CROSS APPLY” operator): static IEnumerable<R> SelectMany<T, R>(this IEnumerable<T> source, Func<T, IEnumerable<R>> collectionSelector) It instead uses SelectMany as a convenient syntactic representation of an inner join. The parameter to the selector function is thus unavailable. Because the parameter isn’t supported, its type in StreamInsight 1.0 – 2.0 wasn’t carefully scrutinized. Unfortunately, the type chosen for the parameter is nonsensical to LINQ programmers: static CepStream<R> SelectMany<T, R>(this CepStream<T> source, Expression<Func<CepStream<T>, CepStream<R>>> streamSelector) Using Unit as the type for the parameter accurately reflects the StreamInsight’s capabilities: static IQStreamable<R> SelectMany<T, R>(this IQStreamable<T> source, Expression<Func<Unit, IQStreamable<R>>> streamSelector) For queries that succeed – that is, queries that do not reference the stream selector parameter – there is no difference between the code written for the two overloads: from x in xs from y in ys select f(x, y) Top-K The Take operator used in StreamInsight causes confusion for LINQ programmers because it is applied to the (unbounded) stream rather than the (bounded) window, suggesting that the query as a whole will return k rows: (from win in xs.SnapshotWindow() from x in win orderby x.A select x.B).Take(k) The use of SelectMany is also unfortunate in this context because it implies the availability of the window parameter within the remainder of the comprehension. The following compiles but fails at runtime: (from win in xs.SnapshotWindow() from x in win orderby x.A select win).Take(k) The Take operator in 2.1 is applied to the window rather than the stream: Before After (from win in xs.SnapshotWindow() from x in win orderby x.A select x.B).Take(k) from win in xs.SnapshotWindow() from b in     (from x in win     orderby x.A     select x.B).Take(k) select b Multicast We are introducing an explicit multicast operator in order to preserve expression identity, which is important given the semantics about moving code to and from StreamInsight. This also better matches existing LINQ dialects, such as Reactive. This pattern enables expressing multicasting in two ways: Implicit Explicit var ys = from x in xs          where x.A > 1          select x; var zs = from y1 in ys          from y2 in ys.ShiftEventTime(_ => TimeSpan.FromSeconds(1))          select y1 + y2; var ys = from x in xs          where x.A > 1          select x; var zs = ys.Multicast(ys1 =>     from y1 in ys1     from y2 in ys1.ShiftEventTime(_ => TimeSpan.FromSeconds(1))     select y1 + y2; Notice the product translates an expression using implicit multicast into an expression using the explicit multicast operator. The user does not see this translation. Default window policies Only default window policies are supported in the new surface. Other policies can be simulated by using AlterEventLifetime. Before After xs.SnapshotWindow(     WindowInputPolicy.ClipToWindow,     SnapshotWindowInputPolicy.Clip) xs.SnapshotWindow() xs.TumblingWindow(     TimeSpan.FromSeconds(1),     HoppingWindowOutputPolicy.PointAlignToWindowEnd) xs.TumblingWindow(     TimeSpan.FromSeconds(1)) xs.TumblingWindow(     TimeSpan.FromSeconds(1),     HoppingWindowOutputPolicy.ClipToWindowEnd) Not supported … LeftAntiJoin Representation of LASJ as a correlated sub-query in the LINQ surface is problematic as the StreamInsight engine does not support correlated sub-queries (see discussion of SelectMany). The current syntax requires the introduction of an otherwise unsupported ‘IsEmpty()’ operator. As a result, the pattern is not discoverable and implies capabilities not present in the server. The direct representation of LASJ is used instead: Before After from x in xs where     (from y in ys     where x.A > y.B     select y).IsEmpty() select x xs.LeftAntiJoin(ys, (x, y) => x.A > y.B) from x in xs where     (from y in ys     where x.A == y.B     select y).IsEmpty() select x xs.LeftAntiJoin(ys, x => x.A, y => y.B) ApplyWithUnion The ApplyWithUnion methods have been deprecated since their signatures are redundant given the standard SelectMany overloads: Before After xs.GroupBy(x => x.A).ApplyWithUnion(gs => from win in gs.SnapshotWindow() select win.Count()) xs.GroupBy(x => x.A).SelectMany(     gs =>     from win in gs.SnapshotWindow()     select win.Count()) xs.GroupBy(x => x.A).ApplyWithUnion(gs => from win in gs.SnapshotWindow() select win.Count(), r => new { r.Key, Count = r.Payload }) from x in xs group x by x.A into gs from win in gs.SnapshotWindow() select new { gs.Key, Count = win.Count() } Alternate UDO syntax The representation of UDOs in the StreamInsight LINQ dialect confuses cardinalities. Based on the semantics of user-defined operators in StreamInsight, one would expect to construct queries in the following form: from win in xs.SnapshotWindow() from y in MyUdo(win) select y Instead, the UDO proxy method is referenced within a projection, and the (many) results returned by the user code are automatically flattened into a stream: from win in xs.SnapshotWindow() select MyUdo(win) The “many-or-one” confusion is exemplified by the following example that compiles but fails at runtime: from win in xs.SnapshotWindow() select MyUdo(win) + win.Count() The above query must fail because the UDO is in fact returning many values per window while the count aggregate is returning one. Original syntax New alternate syntax from win in xs.SnapshotWindow() select win.UdoProxy(1) from win in xs.SnapshotWindow() from y in win.UserDefinedOperator(() => new Udo(1)) select y -or- from win in xs.SnapshotWindow() from y in win.UdoMacro(1) select y Notice that this formulation also sidesteps the dynamic type pitfalls of the existing “proxy method” approach to UDOs, in which the type of the UDO implementation (TInput, TOuput) and the type of its constructor arguments (TConfig) need to align in a precise and non-obvious way with the argument and return types for the corresponding proxy method. UDSO syntax UDSO currently leverages the DataContractSerializer to clone initial state for logical instances of the user operator. Initial state will instead be described by an expression in the new LINQ surface. Before After xs.Scan(new Udso()) xs.Scan(() => new Udso()) Name changes ShiftEventTime => AlterEventStartTime: The alter event lifetime overload taking a new start time value has been renamed. CountByStartTimeWindow => CountWindow

    Read the article

  • Changes to the LINQ-to-StreamInsight Dialect

    - by Roman Schindlauer
    In previous versions of StreamInsight (1.0 through 2.0), CepStream<> represents temporal streams of many varieties: Streams with ‘open’ inputs (e.g., those defined and composed over CepStream<T>.Create(string streamName) Streams with ‘partially bound’ inputs (e.g., those defined and composed over CepStream<T>.Create(Type adapterFactory, …)) Streams with fully bound inputs (e.g., those defined and composed over To*Stream – sequences or DQC) The stream may be embedded (where Server.Create is used) The stream may be remote (where Server.Connect is used) When adding support for new programming primitives in StreamInsight 2.1, we faced a choice: Add a fourth variety (use CepStream<> to represent streams that are bound the new programming model constructs), or introduce a separate type that represents temporal streams in the new user model. We opted for the latter. Introducing a new type has the effect of reducing the number of (confusing) runtime failures due to inappropriate uses of CepStream<> instances in the incorrect context. The new types are: IStreamable<>, which logically represents a temporal stream. IQStreamable<> : IStreamable<>, which represents a queryable temporal stream. Its relationship to IStreamable<> is analogous to the relationship of IQueryable<> to IEnumerable<>. The developer can compose temporal queries over remote stream sources using this type. The syntax of temporal queries composed over IQStreamable<> is mostly consistent with the syntax of our existing CepStream<>-based LINQ provider. However, we have taken the opportunity to refine certain aspects of the language surface. Differences are outlined below. Because 2.1 introduces new types to represent temporal queries, the changes outlined in this post do no impact existing StreamInsight applications using the existing types! SelectMany StreamInsight does not support the SelectMany operator in its usual form (which is analogous to SQL’s “CROSS APPLY” operator): static IEnumerable<R> SelectMany<T, R>(this IEnumerable<T> source, Func<T, IEnumerable<R>> collectionSelector) It instead uses SelectMany as a convenient syntactic representation of an inner join. The parameter to the selector function is thus unavailable. Because the parameter isn’t supported, its type in StreamInsight 1.0 – 2.0 wasn’t carefully scrutinized. Unfortunately, the type chosen for the parameter is nonsensical to LINQ programmers: static CepStream<R> SelectMany<T, R>(this CepStream<T> source, Expression<Func<CepStream<T>, CepStream<R>>> streamSelector) Using Unit as the type for the parameter accurately reflects the StreamInsight’s capabilities: static IQStreamable<R> SelectMany<T, R>(this IQStreamable<T> source, Expression<Func<Unit, IQStreamable<R>>> streamSelector) For queries that succeed – that is, queries that do not reference the stream selector parameter – there is no difference between the code written for the two overloads: from x in xs from y in ys select f(x, y) Top-K The Take operator used in StreamInsight causes confusion for LINQ programmers because it is applied to the (unbounded) stream rather than the (bounded) window, suggesting that the query as a whole will return k rows: (from win in xs.SnapshotWindow() from x in win orderby x.A select x.B).Take(k) The use of SelectMany is also unfortunate in this context because it implies the availability of the window parameter within the remainder of the comprehension. The following compiles but fails at runtime: (from win in xs.SnapshotWindow() from x in win orderby x.A select win).Take(k) The Take operator in 2.1 is applied to the window rather than the stream: Before After (from win in xs.SnapshotWindow() from x in win orderby x.A select x.B).Take(k) from win in xs.SnapshotWindow() from b in     (from x in win     orderby x.A     select x.B).Take(k) select b Multicast We are introducing an explicit multicast operator in order to preserve expression identity, which is important given the semantics about moving code to and from StreamInsight. This also better matches existing LINQ dialects, such as Reactive. This pattern enables expressing multicasting in two ways: Implicit Explicit var ys = from x in xs          where x.A > 1          select x; var zs = from y1 in ys          from y2 in ys.ShiftEventTime(_ => TimeSpan.FromSeconds(1))          select y1 + y2; var ys = from x in xs          where x.A > 1          select x; var zs = ys.Multicast(ys1 =>     from y1 in ys1     from y2 in ys1.ShiftEventTime(_ => TimeSpan.FromSeconds(1))     select y1 + y2; Notice the product translates an expression using implicit multicast into an expression using the explicit multicast operator. The user does not see this translation. Default window policies Only default window policies are supported in the new surface. Other policies can be simulated by using AlterEventLifetime. Before After xs.SnapshotWindow(     WindowInputPolicy.ClipToWindow,     SnapshotWindowInputPolicy.Clip) xs.SnapshotWindow() xs.TumblingWindow(     TimeSpan.FromSeconds(1),     HoppingWindowOutputPolicy.PointAlignToWindowEnd) xs.TumblingWindow(     TimeSpan.FromSeconds(1)) xs.TumblingWindow(     TimeSpan.FromSeconds(1),     HoppingWindowOutputPolicy.ClipToWindowEnd) Not supported … LeftAntiJoin Representation of LASJ as a correlated sub-query in the LINQ surface is problematic as the StreamInsight engine does not support correlated sub-queries (see discussion of SelectMany). The current syntax requires the introduction of an otherwise unsupported ‘IsEmpty()’ operator. As a result, the pattern is not discoverable and implies capabilities not present in the server. The direct representation of LASJ is used instead: Before After from x in xs where     (from y in ys     where x.A > y.B     select y).IsEmpty() select x xs.LeftAntiJoin(ys, (x, y) => x.A > y.B) from x in xs where     (from y in ys     where x.A == y.B     select y).IsEmpty() select x xs.LeftAntiJoin(ys, x => x.A, y => y.B) ApplyWithUnion The ApplyWithUnion methods have been deprecated since their signatures are redundant given the standard SelectMany overloads: Before After xs.GroupBy(x => x.A).ApplyWithUnion(gs => from win in gs.SnapshotWindow() select win.Count()) xs.GroupBy(x => x.A).SelectMany(     gs =>     from win in gs.SnapshotWindow()     select win.Count()) xs.GroupBy(x => x.A).ApplyWithUnion(gs => from win in gs.SnapshotWindow() select win.Count(), r => new { r.Key, Count = r.Payload }) from x in xs group x by x.A into gs from win in gs.SnapshotWindow() select new { gs.Key, Count = win.Count() } Alternate UDO syntax The representation of UDOs in the StreamInsight LINQ dialect confuses cardinalities. Based on the semantics of user-defined operators in StreamInsight, one would expect to construct queries in the following form: from win in xs.SnapshotWindow() from y in MyUdo(win) select y Instead, the UDO proxy method is referenced within a projection, and the (many) results returned by the user code are automatically flattened into a stream: from win in xs.SnapshotWindow() select MyUdo(win) The “many-or-one” confusion is exemplified by the following example that compiles but fails at runtime: from win in xs.SnapshotWindow() select MyUdo(win) + win.Count() The above query must fail because the UDO is in fact returning many values per window while the count aggregate is returning one. Original syntax New alternate syntax from win in xs.SnapshotWindow() select win.UdoProxy(1) from win in xs.SnapshotWindow() from y in win.UserDefinedOperator(() => new Udo(1)) select y -or- from win in xs.SnapshotWindow() from y in win.UdoMacro(1) select y Notice that this formulation also sidesteps the dynamic type pitfalls of the existing “proxy method” approach to UDOs, in which the type of the UDO implementation (TInput, TOuput) and the type of its constructor arguments (TConfig) need to align in a precise and non-obvious way with the argument and return types for the corresponding proxy method. UDSO syntax UDSO currently leverages the DataContractSerializer to clone initial state for logical instances of the user operator. Initial state will instead be described by an expression in the new LINQ surface. Before After xs.Scan(new Udso()) xs.Scan(() => new Udso()) Name changes ShiftEventTime => AlterEventStartTime: The alter event lifetime overload taking a new start time value has been renamed. CountByStartTimeWindow => CountWindow

    Read the article

  • Entity Framework naming conventions for many-to-many link tables

    - by TimothyP
    Hi, We are designing a SQL Server database with link tables for many-to-many relations. The question is are there any best practices for naming these kinds of tables for use with the entity framework? Let's say there's a table Customer and Address Then there is a link table between them, what do we call it? CustomerAddress ? Or something else? Thnx

    Read the article

  • How to create entities in one Entity group ?

    - by Gopi
    I am building an app based on google app engine (Java) using JDO for persistence. Can someone give me an example or a point me to some code which shows persisting of multiple entities (of same type) using javax.jdo.PersistenceManager.makePersistentAll() within a transaction. Basically I need to understand how to put multiple entites in one Entity Group so that they can be saved using makePersistentAll() inside transaction.

    Read the article

  • Entity Framework 4 missing features?

    - by Roger Alsing
    I'm well aware that similair topics have been brought up before e.g. http://stackoverflow.com/questions/1639043/entity-framework-4-vs-nhibernate But instead of arguments like: NHibernate have been around longer and is more mature EF4 is drag n drop and not enterprisy EF4 and LinqToSql are ... I would like to see a more detailed list of features that you consider missing from EF4. Personally, I think the lack of enum support is the biggest drawback of EF4.

    Read the article

  • Repository Pattern: SaveOrUpdate() in Entity Framework and L2S

    - by JMSA
    These web articles uses separate Save() and Update() methods in the repository pattern. I am using repository pattern. How can I write a SaveOrUpdate() method in Entity Framework with the help of ObjectContext and in Linq-To-SQL with the help of DataContext? That is, how can I write a single method that shall do both save and update job?

    Read the article

< Previous Page | 8 9 10 11 12 13 14 15 16 17 18 19  | Next Page >