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  • LINQ TO SQL error: An attempt has been made to Attach or Add an entity that is not new...

    - by Collin Estes
    "An attempt has been made to Attach or Add an entity that is not new, perhaps having been loaded from another DataContext. This is not supported." I have scene a lot of solutions dealing with the Attach() method but I'm just trying to add in a new record. Not sure what is going on. Here is my code, It is failing on the star'd line.: try { LINQDataContext datacontext = new LINQDataContext(); TrackableItem ti = datacontext.TrackableItems.FirstOrDefault(_t => _t.pkId == obj.fkTrackableItemId); arcTrackableItem ati = new arcTrackableItem(); ati.barcode = ti.barcode; ati.dashNumber = ti.dashNumber; ati.dateDown = ti.dateDown; ati.dateUp = ti.dateUp; ati.fkItemStatusId = ti.fkItemStatusId; ati.fkItemTypeId = ti.fkItemTypeId; ati.partNumber = ti.partNumber; ati.serialNumber = ti.serialNumber; ati.archiveDate = DateTime.Now; datacontext.arcTrackableItems.InsertOnSubmit(ati); datacontext.SubmitChanges(); arcPWR aItem = new arcPWR(); aItem.comments = obj.comments; aItem.fkTrackableItemId = ati.pkId; aItem.fkPWRStatusId = obj.fkPWRStatusId; aItem.PwrStatus = obj.PwrStatus; **datacontext.arcPWRs.InsertOnSubmit(aItem);** datacontext.SubmitChanges();

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  • Alternative of SortedDictionary in Silverlight

    - by Rajneesh Verma
    Hi, As we know SortedDictionary is not not present in Silverlightso to find alternative of this i am using Dictionary as System.Collections.Generic . Dictionary (Of TKey, TValue ) . KeyCollection and for sorting i am using LINQ query. see the full code below. Dim sortedLists As New Dictionary(Of String, Object) Dim query = From sortedList In sortedLists Order By sortedList.Key Ascending Select sortedList.Key, sortedList.Value For Each que In query 'get the key value using que.Key 'get the value using...(read more)

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  • Best algorithm/practice when creating a search mechanism for your database?

    - by Alex Hope O'Connor
    I have been designing a database where it is very important to provide users with a good search mechanism. So I was wondering what some of the best practices are for using keywords to search over multiple database tables and return the relevent records? Some other things I am curious about: The users location, if they provide an address The speed of the algorithm Additional Information: I am using C# and LINQ-To-SQL.

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  • How can I achieve strong typing with a component messaging system?

    - by Vaughan Hilts
    I'm looking at implementing a messaging system in my entity component system. I've deduced that I can use an event / queue for passing messages, but right now, I just use a generic object and cast out the data I want. I also considered using a dictionary. I see a lot of information on this, but they all involve a lot of casting and guessing. Is there any way to do this elegantly and keep strong typing on my messages?

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  • How can I efficiently update only the entities that matter in a given frame?

    - by lezebulon
    I'm making a RTS, which can potentially have lots of units in one map (think Age of Empires). I'm looking for a way to update my units. I want to avoid calling a virtual Update() method every frame on every entity. On the other hand, units that are not in view should still be updated and behave "normally." I'm assuming this is a fairly standard question; what would be a way to handle this situation?

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  • LINQPad still being used much out there?

    - by CoffeeAddict
    I'm trying to guage how popular and how used LINQPad is today. I'm just wondering if it's still a useful tool or not as VS and other tools have gotten better. Furthermore, I am coding over LLBGen by working with LINQ to SQL. I see there is a plug-in for LLBGen and LINQPad. Still I wonder if LINQPad is really worth it or what benefits it can give me or if it's still highly suggested out there for ORMs, etc.

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  • Why does the entity framework need an ICollection for lazy loading?

    - by Akk
    I want to write a rich domain class such as public class Product { public IEnumerable<Photo> Photos {get; private set;} public void AddPhoto(){...} public void RemovePhoto(){...} } But the entity framework (V4 code first approach) requires an ICollection type for lazy loading! The above code no longer works as designed since clients can bypass the AddPhoto / RemovePhoto method and directly call the add method on ICollection. This is not good. public class Product { public ICollection<Photo> Photos {get; private set;} //Bad public void AddPhoto(){...} public void RemovePhoto(){...} } It's getting really frustrating trying to implement DDD with the EF4. Why did they choose the ICollection for lazy loading? How can i overcome this? Does NHibernate offer me a better DDD experience?

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  • Trying to edit an entity with data from dropdowns in MVC...

    - by user598352
    Hello! I'm having trouble getting my head around sending multiple models to a view in mvc. My problem is the following. Using EF4 I have a table with attributes organised by category. Couldn't post an image :-( [Have a table called attributes (AttributeTitle, AttributeName, CategoryID) connected to a table called Category (CategoryTitle).] What I want to do is be able to edit an attribute entity and have a dropdown of categories to choose from. I tried to make a custom viewmodel public class AttributeViewModel { public AttributeViewModel() { } public Attribute Attribute { get; set; } public IQueryable<Category> AllCategories { get; set; } } But it just ended up being a mess. <div class="editor-field"> <%: Html.DropDownList("Category", new SelectList((IEnumerable)Model.AllCategories, "CategoryID", "CategoryName")) %> </div> I was getting it back to the controller... [HttpPost] public ActionResult Edit(int AttributeID, FormCollection formcollection) { var _attribute = ProfileDB.GetAttribute(AttributeID); int _selcategory = Convert.ToInt32(formcollection["Category"]); _attribute.CategoryID = (int)_selcategory; try { UpdateModel(_attribute); (<---Error here) ProfileDB.SaveChanges(); return RedirectToAction("Index"); } catch (Exception e) { return View(_attribute); } } I've debugged the code and my _attribute looks correct and _attribute.CategoryID = (int)_selcategory updates the model, but then I get the error. Somewhere here I thought that there should be a cleaner way to do this, and that if I could only send two models to the view instead of having to make a custom viewmodel. To sum it up: I want to edit my attribute and have a dropdown of all of the available categories. Any help much appreciated!

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  • How do you make use of the provider independency in the Entity Framework?

    - by Anders Svensson
    I'm trying to learn more about data access and the Entity Framework. My goal is to have a "provider independent" data access layer (to be able to switch easily e.g. from SQL Server to MySQL or vice versa), and since the EF is supposed to be provider independent it seems like a good way to go. But how do you use this provider independence? I mean, I was expecting to be able to sort of "program to an interface", and then just be able to switch database provider. But as far as I can tell I'm only getting a concrete type to program against, an "Entities" class, e.g. in my case it is: UserDBEntities _context = new UserDBEntities(); What I would have expected to be able to switch provider easily was to have an interface e.g. like IEntities _context = new UserDBEntities(); Sort of like I can do with datasets... But maybe that isn't how it works at all with EF? Or do you just switch provider in the connectionstring, and the model stays the same?? Please remember that I'm a complete newbie at this EF, and rather inexperienced with databases in general, so I would really appreciate if you could be as clear as possible :-)

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  • Accessing both stored procedure output parameters AND the result set in Entity Framework?

    - by MS.
    Is there any way of accessing both a result set and output parameters from a stored procedure added in as a function import in an Entity Framework model? I am finding that if I set the return type to "None" such that the designer generated code ends up calling base.ExecuteFunction(...) that I can access the output parameters fine after calling the function (but of course not the result set). Conversely if I set the return type in the designer to a collection of complex types then the designer generated code calls base.ExecuteFunction<T>(...) and the result set is returned as ObjectResult<T> but then the value property for the ObjectParameter instances is NULL rather than containing the proper value that I can see being passed back in Profiler. I speculate the second method is perhaps calling a DataReader and not closing it. Is this a known issue? Any work arounds or alternative approaches? Edit My code currently looks like public IEnumerable<FooBar> GetFooBars( int? param1, string param2, DateTime from, DateTime to, out DateTime? createdDate, out DateTime? deletedDate) { var createdDateParam = new ObjectParameter("CreatedDate", typeof(DateTime)); var deletedDateParam = new ObjectParameter("DeletedDate", typeof(DateTime)); var fooBars = MyContext.GetFooBars(param1, param2, from, to, createdDateParam, deletedDateParam); createdDate = (DateTime?)(createdDateParam.Value == DBNull.Value ? null : createdDateParam.Value); deletedDate = (DateTime?)(deletedDateParam.Value == DBNull.Value ? null : deletedDateParam.Value); return fooBars; }

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  • What to set the scalar type to contain a byte []. Entity in MVC2

    - by Brad8118
    I'm trying out the EF 4.0 and using the Model first approach. I'd like to store images into the database and I'm not sure of the best type for the scalar in the entity. I currently have it(the image scalar type) setup as a binary. From what I have been reading the best way to store the image in the db is a byte[]. So I'm assuming that binary is the way to go. If there is a better way I'd switch. In my controller I have: //file from client to store in the db HttpPostedFileBase file = Request.Files[inputTagName]; if (file.ContentLength > 0) { keyToAdd.Image = new byte[file.ContentLength]; file.InputStream.Write(keyToAdd.Image, 0, file.ContentLength); } This builds fine but when I run it I get an exception writing the stream to keyToAdd.Image. The exception is something like: Method does not exist. Any ideas? Note that when using a EF 4.0 model first approach I only have int16, int32, double, string, decimal, binary, byte, DateTime, Double, Single, and SByte as available types. Thanks

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  • Why newly created entity object with navigation property is automaticly added to ObjectContext?

    - by Levelbit
    I have to entities: Company and Location (one to many). When I create new Location entity object and assign navigation property(Company) with the navigation property of already existing Location object (Location _new = new Location(); _new.Company = _old.Company). It seems that at that point newly created object is added to Object Context automatically, because when I call SaveChanges method that object is insert to database although I didn't call ObjectContext.AddObject(_new). I'm new in EF so there is probably reason why I have result like this? Is there need to assign also CompanyReference filed too and how to do it? IDaoFactory daoFactory = new DaoFactory(); ILocationDao locaitonDao = daoFactory.GetLocationDao(); IEnumerable<Location> locations = locaitonDao.GetLocations(); Location _old = locations.First(); Location _new = new Location(); _new.LocationName = _old.LocationName; _new.Company = _old.Company;// 1 _new.Address = _old.Address; //... ContactEntities.SaveChanges();//2 If I execute line (1) instantly _new object is added to object context and I can see additional datarow in my datagrid after line (2) is executed.

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  • T-SQL selecting values that match ISNUMERIC and also are within a specified range. (plus Linq-to-sql

    - by Toby
    I am trying to select rows from a table where one of the (NVARCHAR) columns is within a numeric range. SELECT ID, Value FROM Data WHERE ISNUMERIC(Value) = 1 AND CONVERT(FLOAT, Value) < 66.6 Unfortunately as part of the SQL spec the AND clauses don't have to short circuit (and don't on MSSQL Server EE 2008). More info: http://stackoverflow.com/questions/789231/is-the-sql-where-clause-short-circuit-evaluated My next attempt was to try this to see if I could achieve delayed evaluation of the CONVERT SELECT ID, Value FROM Data WHERE (CASE WHEN ISNUMERIC(Value) = 1 THEN CONVERT(FLOAT, Value) < 66.6 ELSE 0 END) but I cannot seem to use a < (or any comparison) with the result of a CONVERT. It fails with the error Incorrect syntax near '<'. I can get away with SELECT ID, CONVERT(FLOAT, Value) AS Value FROM Data WHERE ISNUMERIC(Value) = 1 So the obvious solution is to wrap the whole select statement in another SELECT and WHERE and return the converted values from the inner select and filter in there where of the outer select. Unfortunately this is where my Linq-to-sql problem comes in. I am filtering not only by one range but potentialy by many, or just by the existance of the record (there are some date range selects and comparisons I've left out.) Essentially I would like to be able to generate something like this: SELECT ID, TypeID, Value FROM Data WHERE (TypeID = 4 AND ISNUMERIC(Value) AND CONVERT(Float, Value) < 66.6) OR (TypeID = 8 AND ISNUMERIC(Value) AND CONVERT(Float, Value) > 99) OR (TypeID = 9) (With some other clauses in each of those where options.) This clearly doesn't work if I filter out the non-ISNUMERIC values in an inner select. As I mentioned I am using Linq-to-sql (and PredicateBulider) to build up these queries but unfortunately Datas.Where(x => ISNUMERIC(x.Value) ? Convert.ToDouble(x.Value) < 66.6 : false) Gets converted to this which fails the initial problem. WHERE (ISNUMERIC([t0].[Value]) = 1) AND ((CONVERT(Float,[t0].[Value])) < @p0) My last resort will have to be to outer join against a double select on the same table for each of the comparisons but this isn't really an idea solution. I was wondering if anyone has run into similar issues before?

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  • How to rewrite this SQL statement to LINQ 2 SQL ?

    - by Shyju
    How can i convert this SQL query to its equivalent LINQ 2 SQL statement for VB.NET? SELECT COUNT(*) AS 'Qty', IV200.itemnmbr, IV200.locncode, IV200.bin, CAST(IV112.Quantity as int) as 'Qty2' , 'parentBIN' = isnull(MDS.parentBIN,iv112.bin) From IV00200 IV200 (nolock) inner join IV00112 IV112 (nolock) on iv200.itemnmbr = iv112.itemnmbr and IV200.bin = IV112.bin and iv200.locncode = iv112.locncode left outer join mds_container mds (nolock) on isnull(mds.locncode,'nul') = isnull(iv112.locncode,'nul') and isnull(mds.containerbin,'nul') = isnull(iv112.bin,'nul') where IV200.bin = 'MU7I336A80' group by IV200.itemnmbr, IV200.locncode, IV200.bin, IV112.Quantity, isnull(MDS.parentBIN,iv112.bin) order by IV200.itemnmbr

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  • Linq/C#: Selecting and summing items from the result of a group by?

    - by Andrew White
    Hi, I have a list like this: City Total Sydney 11 Dublin 9 London 12 Dublin 3 London 9 Sydney 12 I first of all need to Group By City & Sum Total so I have Sydney 23 Dublin 12 London 21 Next I need to filter for those that entries where the total is 20 Sydney 23 London 21 And what I finally need is the total of these entries, e.g. 44 I really want to do it in 1 single LINQ statement, possible? Thx,

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  • VB .Net LINQ query to determine whether more than one element has the same value for a property?

    - by Alex Hope O'Connor
    I am trying to write a LINQ query which will return true if there are multiple objects which have a property with the same value. Here is what I have come up with so far: Formatters.Where(Function(f As DataModel.Formatter) _ Formatters.Select(Function(f2 As DataModel.Formatter) f2.Name.ToLower()).Contains(f.Name.ToLower())).Count > 1 However the above always returns true as long as their are more then 1 elements in the list, can someone please give me a hand with this? Thanks, Alex.

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  • How can I iterate over a collection of objects returned by a LINQ-to-XML query?

    - by billmaya
    I've got this XML: <BillingLog> <BillingItem> <date-and-time>2003-11-04</date-and-time> <application-name>Billing Service</application-name> <severity>Warning</severity> <process-id>123</process-id> <description>Timed out on a connection</description> <detail>Timed out after three retries.</detail> </BillingItem> <BillingItem> <date-and-time>2010-05-15</date-and-time> <application-name>Callback Service</application-name> <severity>Error</severity> <process-id>456</process-id> <description>Unable to process callback</description> <detail>Reconciliation timed out after two retries.</detail> </BillingItem> </BillingLog> That I want to project using LINQ-to-XML into a collection of BillingItem objects contained in a single BillingLog object. public class BillingLog { public IEnumerable<BillingItem> items { get; set; } } public class BillingItem { public string Date { get; set; } public string ApplicationName { get; set; } public string Severity { get; set; } public int ProcessId { get; set; } public string Description { get; set; } public string Detail { get; set;} } This is the LINQ query that I'm using to project the XML (which is contained in the string variable source). XDocument xdoc = XDocument.Parse(source); var log = from i in xdoc.Elements("BillingLog") select new BillingLog { items = from j in i.Descendants("BillingItem") select new BillingItem { Date = (string)j.Element("date-and-time"), ApplicationName = (string)j.Element("application-name"), Severity = (string)j.Element("severity"), ProcessId = (int)j.Element("process-id"), Description = (string)j.Element("description"), Detail = (string)j.Element("detail") } }; When I try and iterate over the objects in log using foreach. foreach (BillingItem item in log) { Console.WriteLine ("{0} | {1} | {2} | {3} | {4} | {5}", item.Date, item.ApplicationName, item.Severity, item.ProcessId.ToString(), item.Description, item.Detail); } I get the following error message from LINQPad. Cannot convert type 'UserQuery.BillingLog' to 'UserQuery.BillingItem' Thanks in advance.

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  • What is the most elegant way to implement a business rule relating to a child collection in LINQ?

    - by AaronSieb
    I have two tables in my database: Wiki WikiId ... WikiUser WikiUserId (PK) WikiId UserId IsOwner ... These tables have a one (Wiki) to Many (WikiUser) relationship. How would I implement the following business rule in my LINQ entity classes: "A Wiki must have exactly one owner?" I've tried updating the tables as follows: Wiki WikiId (PK) OwnerId (FK to WikiUser) ... WikiUser WikiUserId (PK) WikiId UserId ... This enforces the constraint, but if I remove the owner's WikiUser record from the Wiki's WikiUser collection, I recieve an ugly SqlException. This seems like it would be difficult to catch and handle in the UI. Is there a way to perform this check before the SqlException is generated? A better way to structure my database? A way to catch and translate the SqlException to something more useful? Edit: I would prefer to keep the validation rules within the LINQ entity classes if possible. Edit 2: Some more details about my specific situation. In my application, the user should be able to remove users from the Wiki. They should be able to remove any user, except the user who is currently flagged as the "owner" of the Wiki (a Wiki must have exactly one owner at all times). In my control logic, I'd like to use something like this: wiki.WikiUsers.Remove(wikiUser); mRepository.Save(); And have any broken rules transferred to the UI layer. What I DON'T want to have to do is this: if(wikiUser.WikiUserId != wiki.OwnerId) { wiki.WikiUsers.Remove(wikiUser); mRepository.Save(); } else { //Handle errors. } I also don't particularly want to move the code to my repository (because there is nothing to indicate not to use the native Remove functions), so I also DON'T want code like this: mRepository.RemoveWikiUser(wiki, wikiUser) mRepository.Save(); This WOULD be acceptable: try { wiki.WikiUsers.Remove(wikiUser); mRepository.Save(); } catch(ValidationException ve) { //Display ve.Message } But this catches too many errors: try { wiki.WikiUsers.Remove(wikiUser); mRepository.Save(); } catch(SqlException se) { //Display se.Message } I would also PREFER NOT to explicitly call a business rule check (although it may become necessary): wiki.WIkiUsers.Remove(wikiUser); if(wiki.CheckRules()) { mRepository.Save(); } else { //Display broken rules }

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