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  • form data posted using linq-to-sql not showing until I refresh the page

    - by PeteShack
    I have an asp.net mvc app with a form. When you submit the form, it adds records to the sql database with linq-to-sql. After adding the records, the controller displays the form again, and should show those new values on the form. But, when it displays the form, the values are blank, until you refresh the page. While tracing through the code, I can see the records being added to the database when they are submitted, but the view doesnt display them, unless I refresh. The view is not the problem, it just displays the view model, which is missing the new records immediately after the post. I know this is kind of vague, but wasnt sure what parts of code to include here. Could this have something to do with data context life cycle? Basically, there is a data context created when the form is posted, then a different data context is created in the method that displays the form. Any suggestions on what might be causing this?

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  • Mapping LINQ to SQL table to another very similar table without iterating through every one

    - by Daniel Coffman
    Apologies for the vague question. Here it is: I have a table object created by LINQ to SQL. I am copying entries from one table to an "archive" table that has all the columns of the original, plus a couple extra ones. It feels sloppy to iterate through every object and manually define the mapping like: foreach (oldTable in dbContextOldTables) { var newTable = new NewTable(); newTable.TableID = oldTable.ID; newTable.Title = oldTable.Title; ... (repeat for twenty columns) newTable.ColumnThatIsntInOldTable = "Data that will be the same for every row"; dbContext.NewTables.InsertOnSubmit(newTable); } dbContext.SubmitChanges(); Is there a clever way to do this?

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  • LINQ to SQL - Get only substring from a field

    - by domanokz
    I'm studying ASP.NET MVC and I use LINQ to SQL for model. I have a table named "Note" with the fields "Title" and "Content". The "Content" field can contain thousand characters. What I want to do is to display the LIST of notes in a page. I use table with two columns, for "Title" and SUBSTRING of the "Content" (50 characters). My problem is, I don't know how to edit the model so that it will display only the substring of the "Content". Thanks in advance!

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  • Dynamic "WHERE IN" on IQueryable (linq to SQL)

    - by user320235
    I have a LINQ to SQL query returning rows from a table into an IQueryable object. IQueryable<MyClass> items = from table in DBContext.MyTable select new MyClass { ID = table.ID, Col1 = table.Col1, Col2 = table.Col2 } I then want to perform a SQL "WHERE ... IN ...." query on the results. This works fine using the following. (return results with id's ID1 ID2 or ID3) sQuery = "ID1,ID2,ID3"; string[] aSearch = sQuery.Split(','); items = items.Where(i => aSearch.Contains(i.ID)); What I would like to be able to do, is perform the same operation, but not have to specify the i.ID part. So if I have the string of the field name I want to apply the "WHERE IN" clause to, how can I use this in the .Contains() method?

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  • Help me construct this Linq statement

    - by Geoffrey
    There should be a simple Linq query for what I'm trying to accomplish, but I'm producing some ugly code. I have two tables, one of issues and another of issue status. There is a one-to-many relationship between issue and issue status. When an issue is created an IssueStatus is also created with the status field set to "Open" when it is closed, another IssueStatus is created with the status field set to "Closed" ... but issues can be re-opened. It seems like I should be able to write something like this: public static List<Issue> FindOpenIssues(this IList<Issue> issues) { return ( from issue in issues from issueStatus in issue.issueStatus.OrderBy(x=>x.CreatedOn).Single() where issueStatus.Status == "Open" select issue ).ToList(); } This obviously fails, but there must be a clean way to do this? Thanks!

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  • Next Identity Key LINQ + SQL Server

    - by user569347
    To represent our course tree structure in our Linq Dataclasses we have 2 columns that could potentially be the same as the PK. My problem is that if I want to Insert a new record and populate 2 other columns with the PK that was generated there is no way I can get the next identity and stop conflict with other administrators who might be doing the same insert at the same time. Case: A Leaf node has right_id and left_id = itself (prereq_id) **dbo.pre_req:** prereq_id left_id right_id op_id course_id is_head is_coreq is_enforced parent_course_id and I basically want to do this: pre_req rec = new pre_req { left_id = prereq_id, right_id = prereq_id, op_id = 3, course_id = query.course_id, is_head = true, is_coreq = false, parent_course_id = curCourse.course_id }; db.courses.InsertOnSubmit(rec); try { db.SubmitChanges(); } Any way to solve my dilemma? Thanks!

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  • Using LINQ to filter rows of a matrix based on inclusion in an array

    - by Bob Feng
    I have a matrix, IEnumerable<IEnumerable<int>> matrix, for example: { {10,23,16,20,2,4}, {22,13,1,33,21,11 }, {7,19,31,12,6,22}, ... } and another array: int[] arr={ 10, 23, 16, 20} I want to filter the matrix on the condition that I group all rows of the matrix which contain the same number of elements from arr. That is to say the first row in the matrix {10,23,16,20,2,4} has 4 numbers from arr, this array should be grouped with the rest of the rows with 4 numbers from arr. better to use linq, thank you very much!

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  • SQL to LINQ translating probem

    - by ognjenb
    I have problem with convertion this SQL statement to LINQ : SELECT a.Id, a.Name, a.ArtiklNumber, a.Notes, a.Weight, l.StartDate AS LastStartDate, l.LocationNameId, loc.Name AS CarrentLocation, a.Reserved FROM Accessories a LEFT OUTER JOIN Location l LEFT JOIN LocationName loc ON l.LocationNameId = loc.Id ON a.Id = (SELECT AccessoriesId FROM Location WHERE AccessoriesId = a.Id HAVING MAX(StartDate) = StartDate ) This is part of my translated code: testEntities6 accessoriesEntities = new testEntities6(); var max_StartDate = (from msd in accessoriesEntities.location from d in accessoriesEntities.device where msd.DeviceId == d.Id select msd.StartDate).Min(); var accessories_query = from accs in accessoriesEntities.accessories join l in accessoriesEntities.location on accs.Id equals l.AccessoriesId join loc in accessoriesEntities.locationname on l.LocationNameId equals loc.Id select new AccessoriesModel { //Accessories Id = accs.Id, Name = accs.Name, ArtiklNumber = accs.ArtiklNumber, Notes = accs.Notes, Weight = accs.Weight, Reserved = accs.Reserved, //Location LocationNameId = l.LocationNameId, StartDate = max_StartDate,//l.StartDate, //Locationname Loc_name = loc.Name };

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  • Linq to CSV select by column

    - by griegs
    If I have the following (sample) text file; year,2008,2009,2010 income,1000,1500,2000 dividends,100,200,300 net profit,1100,1700,2300 expenses,500,600,500 profit,600,1100,1800 Is there a way in Linq that I can select the expenses for 2010 only? So far I have the following which gets me all the data; var data = File.ReadAllLines(fileName) .Select( l => { var split = l.CsvSplit(); return split; } ); foreach (var item in data) Console.WriteLine("{0}: ${1}", item[0], item[1]);

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  • Select a Dictionary<T1, T2> with LINQ

    - by Rich
    I have used the "select" keyword and extension method to return an IEnumerable<T> with LINQ, but I have a need to return a generic Dictionary<T1, T2> and can't figure it out. The example I learned this from used something in a form similar to the following: IEnumerable<T> coll = from x in y select new SomeClass{ prop1 = value1, prop2 = value2 }; I've also done the same thing with extension methods. I assumed that since the items in a Dictionary<T1, T2> can be iterated as KeyValuePair<T1, T2> that I could just replace "SomeClass" in the above example with "new KeyValuePair<T1, T2> { ...", but that didn't work (Key and Value were marked as readonly, so I could not compile this code). Is this possible, or do I need to do this in multiple steps? Thanks.

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  • Calculate average in LINQ C# with string representation of property name

    - by Paul
    I need to calculate a whole bunch of averages on an List of Surveys. The surveys have lots of properties that are int and double valued. I am creating a business object to handle all the calculations (there are like 100) and I'd rather not code 100 different methods for finding the average for a particular property. I'd like to be able to have the UI pass a string (representing the property) and have the the business object return an average for that property. So, like... int AverageHeightInInches = MyObject.GetIntAverage("HeightInInches"); . . . Then have linq code to calculate the result. Thanks!

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  • Linq - Grouping where items fall in multiple groups?

    - by PirateKitten
    Is it possible using Linq to create a group where items fall into more than one group? Using the following trivial example: public class Data { public string ID; public int From; public int To; } And this list: List<Data> data = new List<Data>() { new Data() { ID = "A", From = 1, To = 3 }, // Call this A new Data() { ID = "B", From = 1, To = 2 }, // Call this B new Data() { ID = "C", From = 2, To = 3 } // Call this C }; I'd like to group by each possible integer in the ranges From and To (though instead of finding the min + max I could supply the query with the range I want, for example 1 to 3), and in each group would be a reference to the Data instance where the grouping int fits in its range. Hard to explain, easier to show each group and the instances I'd expect in each: [Group 1] 1 - A, B [Group 2] 2 - A, B, C [Group 3] 3 - A, C Is this possible? Or must groups be mutually exclusive?

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  • where clause in linq query

    - by masoud
    in the below code "transmittalno.TransID" always has value but "doctranstocon.Transid" sometimes has value and sometimes does not, so when "doctranstocon.Transid" has value I have no problem but when there is not any value, when compare in the where clause like :"transmittalno.TransID == doctranstocon.Transid". It returns error" Object reference not set to an instance of an object." TranstoCons = from doctranstocon in _DocTranstoCons where ( transmittalno.TransID == doctranstocon.Transid ) select doctranstocon.tblTranstoCon I like TranstoCons returns null when there is not any value for " doctranstocon.Transid " How I can handle this error in the below linq query: var query = from transmittalno in _Transmittals Select new TransmittaltoConPresentationModel { TransID = transmittalno.TransID, Transmittal = transmittalno.TRANSMITTAL, TranstoCons = from doctranstocon in _DocTranstoCons where ( transmittalno.TransID == doctranstocon.Transid ) select doctranstocon.tblTranstoCon };

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  • querying nested array elements in C#

    - by the berserker
    I have following object structure, deseralized from XML (WS): <ns2:Category> <ns2:CategoryId>800003</ns2:CategoryId> <ns2:CategoryName>Name1</ns2:CategoryName> <ns2:Categories> <ns2:Category> <ns2:CategoryId>800008</ns2:CategoryId> <ns2:CategoryName>Name2</ns2:CategoryName> <ns2:Categories> <ns2:Category> <ns2:CategoryId>800018</ns2:CategoryId> <ns2:CategoryName>Name3</ns2:CategoryName> <ns2:Categories/> </ns2:Category> <ns2:Category> <ns2:CategoryId>800028</ns2:CategoryId> <ns2:CategoryName>Name4</ns2:CategoryName> <ns2:Categories/> </ns2:Category> </ns2:Categories> </ns2:Category> <ns2:Category> <ns2:CategoryId>800009</ns2:CategoryId> <ns2:CategoryName>Name5</ns2:CategoryName> <ns2:Categories> <ns2:Category> <ns2:CategoryId>800019</ns2:CategoryId> <ns2:CategoryName>Name6</ns2:CategoryName> <ns2:Categories> <ns2:Category> <ns2:CategoryId>800119</ns2:CategoryId> <ns2:CategoryName>Name7</ns2:CategoryName> <ns2:Categories/> </ns2:Category> <ns2:Category> <ns2:CategoryId>800219</ns2:CategoryId> <ns2:CategoryName>Name111</ns2:CategoryName> <ns2:Categories/> </ns2:Category> </ns2:Categories> </ns2:Category> </ns2:Categories> </ns2:Category> </ns2:Categories> </ns2:Category> How would I find Category object with CategoryId 800119 efficiently? So, Im looking for something like FindCategory(long categoryId) - Prefferably with LINQ to objects. Any other option?

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  • Constructor or Explicit cast

    - by Felan
    In working with Linq to Sql I create a seperate class to ferry data to a web page. To simplify creating these ferry objects I either use a specialized constructor or an explicit conversion operator. I have two questions. First which approach is better from a readibility perspective? Second while the clr code that is generated appeared to be the same to me, are there situations where one would be treated different than the other by the compiler (in lambda's or such). Example code (DatabaseFoo uses specialized constructor and BusinessFoo uses explicit operator): public class DatabaseFoo { private static int idCounter; // just to help with generating data public int Id { get; set; } public string Name { get; set; } public DatabaseFoo() { Id = idCounter++; Name = string.Format("Test{0}", Id); } public DatabaseFoo(BusinessFoo foo) { this.Id = foo.Id; this.Name = foo.Name; } } public class BusinessFoo { public int Id { get; set; } public string Name { get; set; } public static explicit operator BusinessFoo(DatabaseFoo foo) { return FromDatabaseFoo(foo); } public static BusinessFoo FromDatabaseFoo(DatabaseFoo foo) { return new BusinessFoo {Id = foo.Id, Name = foo.Name}; } } public class Program { static void Main(string[] args) { Console.WriteLine("Creating the initial list of DatabaseFoo"); IEnumerable<DatabaseFoo> dafoos = new List<DatabaseFoo>() { new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo()}; foreach(DatabaseFoo dafoo in dafoos) Console.WriteLine(string.Format("{0}\t{1}", dafoo.Id, dafoo.Name)); Console.WriteLine("Casting the list of DatabaseFoo to a list of BusinessFoo"); IEnumerable<BusinessFoo> bufoos = from x in dafoos select (BusinessFoo) x; foreach (BusinessFoo bufoo in bufoos) Console.WriteLine(string.Format("{0}\t{1}", bufoo.Id, bufoo.Name)); Console.WriteLine("Creating a new list of DatabaseFoo by calling the constructor taking BusinessFoo"); IEnumerable<DatabaseFoo> fufoos = from x in bufoos select new DatabaseFoo(x); foreach(DatabaseFoo fufoo in fufoos) Console.WriteLine(string.Format("{0}\t{1}", fufoo.Id, fufoo.Name)); } }

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  • Loading the last related record instantly for multiple parent records using Entity framework

    - by Guillaume Schuermans
    Does anyone know a good approach using Entity Framework for the problem described below? I am trying for our next release to come up with a performant way to show the placed orders for the logged on customer. Of course paging is always a good technique to use when a lot of data is available I would like to see an answer without any paging techniques. Here's the story: a customer places an order which gets an orderstatus = PENDING. Depending on some strategy we move that order up the chain in order to get it APPROVED. Every change of status is logged so we can see a trace for statusses and maybe even an extra line of comment per status which can provide some extra valuable information to whoever sees this order in an interface. So an Order is linked to a Customer. One order can have multiple orderstatusses stored in OrderStatusHistory. In my testscenario I am using a customer which has 100+ Orders each with about 5 records in the OrderStatusHistory-table. I would for now like to see all orders in one page not using paging where for each Order I show the last relevant Status and the extra comment (if there is any for this last status; both fields coming from OrderStatusHistory; the record with the highest Id for the given OrderId). There are multiple scenarios I have tried, but I would like to see any potential other solutions or comments on the things I have already tried. Trying to do Include() when getting Orders but this still results in multiple queries launched on the database. Each order triggers an extra query to the database to get all orderstatusses in the history table. So all statusses are queried here instead of just returning the last relevant one, plus 100 extra queries are launched for 100 orders. You can imagine the problem when there are 100000+ orders in the database. Having 2 computed columns on the database: LastStatus, LastStatusInformation and a regular Linq-Query which gets those columns which are available through the Entity-model. The problem with this approach is the fact that those computed columns are determined using a scalar function which can not be changed without removing the formula from the computed column, etc... In the end I am very familiar with SQL and Stored procedures, but since the rest of the data-layer uses Entity Framework I would like to stick to it as long as possible, even though I have my doubts about performance. Using the SQL approach I would write something like this: WITH cte (RN, OrderId, [Status], Information) AS ( SELECT ROW_NUMBER() OVER (PARTITION BY OrderId ORDER BY Id DESC), OrderId, [Status], Information FROM OrderStatus ) SELECT o.Id, cte.[Status], cte.Information AS StatusInformation, o.* FROM [Order] o INNER JOIN cte ON o.Id = cte.OrderId AND cte.RN = 1 WHERE CustomerId = @CustomerId ORDER BY 1 DESC; which returns all orders for the customer with the statusinformation provided by the Common Table Expression. Does anyone know a good approach using Entity Framework?

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  • "Attach or Add an entity that is not new...loaded from another DataContext. This is not supported."

    - by sah302
    Similar error as other questions, but not quite the same, I am not trying to attach anything. What I am trying to do is insert a new row into a linking table, specifically UserAccomplishment. Relations are set in LINQ to User and Accomplishment Tables. I have a generic insert function: Public Function insertRow(ByVal entity As ImplementationType) As Boolean If entity IsNot Nothing Then Dim lcfdatacontext As New LCFDataContext() Try lcfdatacontext.GetTable(Of ImplementationType)().InsertOnSubmit(entity) lcfdatacontext.SubmitChanges() lcfdatacontext.Dispose() Return True Catch ex As Exception Return False End Try Else Return False End If End Function If you try and give UserAccomplishment the two appropriate objects this will naturally crap out if either the User or Accomplishment already exist. It only works when both user and accomplishment don't exist. I expected this behavior. What does work is simply giving the userAccomplishment object a user.id and accomplishment.id and populating the rest of the fields. This works but is kind of awkward to use in my app, it would be much easier to simply pass in both objects and have it work out what already exists and what doesn't. Okay so I made the following (please ignore the fact that this is horribly inefficient because I know it is): Public Class UserAccomplishmentDao Inherits EntityDao(Of UserAccomplishment) Public Function insertLinkerObjectRow(ByVal userAccomplishment As UserAccomplishment) Dim insertSuccess As Boolean = False If Not userAccomplishment Is Nothing Then Dim userDao As New UserDao() Dim accomplishmentDao As New AccomplishmentDao() Dim user As New User() Dim accomplishment As New Accomplishment() 'see if either object already exists in db' user = userDao.getOneByValueOfProperty("Id", userAccomplishment.User.Id) accomplishment = accomplishmentDao.getOneByValueOfProperty("Id", userAccomplishment.Accomplishment.Id) If user Is Nothing And accomplishment Is Nothing Then 'neither the user or the accomplishment exist, both are new so insert them both, typical insert' insertSuccess = Me.insertRow(userAccomplishment) ElseIf user Is Nothing And Not accomplishment Is Nothing Then 'user is new, accomplishment is not new, so just insert the user, and the relation in userAccomplishment' Dim userWithExistingAccomplishment As New UserAccomplishment(userAccomplishment.User, userAccomplishment.Accomplishment.Id, userAccomplishment.LastUpdatedBy) insertSuccess = Me.insertRow(userWithExistingAccomplishment) ElseIf Not user Is Nothing And accomplishment Is Nothing Then 'user is not new, accomplishment is new, so just insert the accomplishment, and the relation in userAccomplishment' Dim existingUserWithAccomplishment As New UserAccomplishment(userAccomplishment.UserId, userAccomplishment.Accomplishment, userAccomplishment.LastUpdatedBy) insertSuccess = Me.insertRow(existingUserWithAccomplishment) Else 'both are not new, just add the relation' Dim userAccomplishmentBothExist As New UserAccomplishment(userAccomplishment.User.Id, userAccomplishment.Accomplishment.Id, userAccomplishment.LastUpdatedBy) insertSuccess = Me.insertRow(userAccomplishmentBothExist) End If End If Return insertSuccess End Function End Class Alright, here I basically check if the supplied user and accomplishment already exists in the db, and if so call an appropriate constructor that will leave whatever already exists empty, but supply the rest of the information so the insert can succeed. However, upon trying an insert: Dim result As Boolean = Me.userAccomplishmentDao.insertLinkerObjectRow(userAccomplishment) In which the user already exists, but the accomplishment does not (the 99% typical scenario) I get the error: "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 debugged this multiple times now and am not sure why this is occuring, if either User or Accomplishment exist, I am not including it in the final object to try to insert. So nothing appears to be attempted to be added. Even in debug, upon insert, the object was set to empty. So the accomplishment is new and the user is empty. 1) Why is it still saying that and how can I fix it ..using my current structure 2) Pre-emptive 'use repository pattern answers' - I know this way kind of sucks in general and I should be using the repository pattern. However, I can't use that in the current project because I don't have time to refactor that due to my non existence knowledge of it and time constraints. The usage of the app is going to so small that the inefficient use of datacontext's and what have you won't matter so much. I can refactor it once it's up and running, but for now I just need to 'push through' with my current structure. Edit: I also just tested this when having both already exists, and only insert each object's IDs into the table, that works. So I guess I could manually insert whichever object doesn't exist as a single insert, then put the ids only into the linking table, but I still don't know why when one object exists, and I make it empty, it doens't work.

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  • How to Loop through LINQ results (VB.NET)

    - by rockinthesixstring
    I've got some code to try and loop through LINQ results, but it doesn't seem to be working. HERE'S THE CODE Public Sub ProcessRequest(ByVal context As System.Web.HttpContext) Implements System.Web.IHttpHandler.ProcessRequest ' the page contenttype is plain text' HttpContext.Current.Response.ContentType = "text/plain" ' store the querystring as a variable' Dim qs As Nullable(Of Integer) = Integer.TryParse(HttpContext.Current.Request.QueryString("ID"), Nothing) ' use the RegionsDataContext' Using RegionDC As New DAL.RegionsDataContext 'create a (q)uery variable' Dim q As Object ' if the querystring PID is not blank' ' then we want to return results based on the PID' If Not qs Is Nothing Then ' that fit within the Parent ID' q = (From r In RegionDC.bt_Regions _ Where r.PID = qs _ Select r.Region).ToArray ' now we loop through the array' ' and write out the ressults' For Each item As DAL.bt_Region In q HttpContext.Current.Response.Write(item.Region & vbCrLf) Next End If End Using End Sub HERE'S THE ERROR Public member 'Region' on type 'String' not found. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.MissingMemberException: Public member 'Region' on type 'String' not found. Source Error: Line 33: ' and write out the ressults Line 34: For Each item In q Line 35: HttpContext.Current.Response.Write(item.Region & vbCrLf) Line 36: Next Line 37: Source File: E:\Projects\businesstrader\App_Code\Handlers\RegionsAutoComplete.vb Line: 35 Stack Trace: [MissingMemberException: Public member 'Region' on type 'String' not found.] Microsoft.VisualBasic.CompilerServices.Container.GetMembers(String& MemberName, Boolean ReportErrors) +509081 Microsoft.VisualBasic.CompilerServices.NewLateBinding.LateGet(Object Instance, Type Type, String MemberName, Object[] Arguments, String[] ArgumentNames, Type[] TypeArguments, Boolean[] CopyBack) +222 BT.Handlers.RegionsAutoComplete.ProcessRequest(HttpContext context) in E:\Projects\businesstrader\App_Code\Handlers\RegionsAutoComplete.vb:35 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +181 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +75 Can anyone tell me what I'm doing wrong?

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  • Linq to SQL EntitySet Binding the MVVM way

    - by Savvas Sopiadis
    Hi everybody! In a WPF application i'm using LINQ to SQL classes (created by SQL Metal, thus implementing POCOs). Let's assume i have a table User and a Table Pictures. These pictures are actually created from one picture, the difference between them may be the size, coloring,... So every user may has more than one Pictures, so the association is 1:N (User:Pictures). My problems: a) how do i bind, in a MVVM manner, a picture control to one picture (i will take one specific picture) in the EntitySet, to show it up? b) everytime a user changes her picture the whole EntitySet should be thrown away and the newly created Picture(s) should be a added. Is this the correct way? e.g. //create the 1st piture object UserPicture1 = new UserPicture(); UserPicture1.Description = "... some description.. "; USerPicture1.Image = imgBytes; //array of bytes //create the 2nd piture object UserPicture2 = new UserPicture(); UserPicture2.Description = "... another description.. "; UserPicture2.Image = DoSomethingWithPreviousImg(imgBytes); //array of bytes //Assuming that the entityset is called Pictures //add these pictures to the corresponding user User.Pictures.Add(UserPicture1); User.Pictures.Add(UserPicture2); //save changes datacontext.Save() Thanks in advance

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  • Update XML element with LINQ to XML in VB.NET

    - by Bayonian
    Hi, I'm trying to update an element in the XML document below: Here's the code: Dim xmldoc As XDocument = XDocument.Load(theXMLSource1) Dim ql As XElement = (From ls In xmldoc.Elements("LabService") _ Where CType(ls.Element("ServiceType"), String).Equals("Scan") _ Select ls.Element("Price")).FirstOrDefault ql.SetValue("23") xmldoc.Save(theXMLSource1) Here's the XML file: <?xml version="1.0" encoding="utf-8"?> <!--Test XML with LINQ to XML--> <LabSerivceInfo> <LabService> <ServiceType>Copy</ServiceType> <Price>1</Price> </LabService> <LabService> <ServiceType>PrintBlackAndWhite</ServiceType> <Price>2</Price> </LabService> </LabSerivceInfo> But, I got this error message: Object reference not set to an instance of an object. Exception Details: System.NullReferenceException: Object reference not set to an instance of an object. Error line:ql.SetValue("23") Can you show me what the problem is? Thank you.

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  • C# PredicateBuilder Entities: The parameter 'f' was not bound in the specified LINQ to Entities quer

    - by Neothor
    I needed to build a dynamic filter and I wanted to keep using entities. Because of this reason I wanted to use the PredicateBuilder from albahari. I created the following code: var invoerDatums = PredicateBuilder.True<OnderzoeksVragen>(); var inner = PredicateBuilder.False<OnderzoeksVragen>(); foreach (var filter in set.RapportInvoerFilter.ToList()) { if(filter.IsDate) { var date = DateTime.Parse(filter.Waarde); invoerDatums = invoerDatums.Or(o => o.Van >= date && o.Tot <= date); } else { string temp = filter.Waarde; inner = inner.Or(o => o.OnderzoekType == temp); } } invoerDatums = invoerDatums.And(inner); var onderzoeksVragen = entities.OnderzoeksVragen .AsExpandable() .Where(invoerDatums) .ToList(); When I ran the code there was only 1 filter which wasn't a date filter. So only the inner predicate was filled. When the predicate was executed I got the following error. The parameter 'f' was not bound in the specified LINQ to Entities query expression. While searching for an answer I found the following page. But this is already implemented in the LINQKit. Does anyone else experienced this error and know how to solve it?

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  • LINQ to Entity, using a SQL LIKE operator

    - by Mario
    I have a LINQ to ENTITY query that pulls from a table, but I need to be able to create a "fuzzy" type search. So I need to add a where clause that searches by lastname IF they add the criteria in the search box (Textbox, CAN be blank --- in which case it pulls EVERYTHING). Here is what I have so far: var query = from mem in context.Member orderby mem.LastName, mem.FirstName select new { FirstName = mem.FirstName, LastName = mem.LastName, }; That will pull everything out of the Member table that is in the Entity object. Then I have an addition to the logic: sLastName = formCollection["FuzzyLastName"].ToString(); if (!String.IsNullOrEmpty(sLastName)) query = query.Where(ln => ln.LastName.Contains(sLastName)); The problem is when the search button is pressed, nothing is returned (0 results). I have run the query against the SQL Server that I expect to happen here and it returns 6 results. This is the query I expect: SELECT mem.LastName, mem.FirstName FROM Members mem WHERE mem.LastName = 'xxx' (when xxx is entered into the textbox) Anyone see anything wrong with this?

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  • Join 3 tables in 1 LINQ-EF

    - by user100161
    I have to fill warehouse table cOrders with program using Ado.NET EF. I have SQL command but i don't know how to do this with LINQ. static void Main(string[] args) { var SPcontex = new PI_NorthwindSPEntities(); var contex = new NorthwindEntities(); dCustomers dimenzijaCustomers = new dCustomers(); dDatum dimenzijaDatum = new dDatum(); ... CREATE TABLE PoslovnaInteligencija.dbo.cOrders( cOrdersID int PRIMARY KEY IDENTITY(1,1), OrderID int NOT NULL, dCustomersID int FOREIGN KEY REFERENCES PoslovnaInteligencija.dbo.dCustomers(dCustomersID), dEmployeesID int FOREIGN KEY REFERENCES PoslovnaInteligencija.dbo.dEmployees(dEmployeesID), OrderDateID int FOREIGN KEY REFERENCES PoslovnaInteligencija.dbo.dDatum(sifDatum), RequiredDateID int FOREIGN KEY REFERENCES PoslovnaInteligencija.dbo.dDatum(sifDatum), ShippedDateID int FOREIGN KEY REFERENCES PoslovnaInteligencija.dbo.dDatum(sifDatum), dShippersID int FOREIGN KEY REFERENCES PoslovnaInteligencija.dbo.dShippers(dShippersID), dShipID int FOREIGN KEY REFERENCES PoslovnaInteligencija.dbo.dShip(dShipID), Freight money, WaitingDay int ) INSERT INTO PoslovnaInteligencija.dbo.cOrders (OrderID, dCustomersID, dEmployeesID, OrderDateID, RequiredDateID, dShippersID, dShipID, Freight, ShippedDateID, WaitingDay) SELECT OrderID, dc.dCustomersID, de.dEmployeesID, orderD.sifDatum, requiredD.sifDatum, dShippersID, ds.dShipID, Freight, ShippedDateID=CASE WHEN (ShippedDate IS NULL) THEN -1 ELSE shippedD.sifDatum END, WaitingDay=CASE WHEN (shippedD.sifDatum - orderD.sifDatum) IS NULL THEN -1 ELSE shippedD.sifDatum - orderD.sifDatum END FROM PoslovnaInteligencija.dbo.dShippers AS s, PoslovnaInteligencija.dbo.dCustomers AS dc, PoslovnaInteligencija.dbo.dEmployees AS de, PoslovnaInteligencija.dbo.dShip AS ds,PoslovnaInteligencija.dbo.dDatum AS orderD, PoslovnaInteligencija.dbo.dDatum AS requiredD, PoslovnaInteligencija.dbo.Orders AS o LEFT OUTER JOIN PoslovnaInteligencija.dbo.dDatum AS shippedD ON shippedD.datum=DATEADD(dd, 0, DATEDIFF(dd, 0, o.ShippedDate)) WHERE o.ShipVia=s.ShipperID AND dc.CustomerID=o.CustomerID AND de.EmployeeID=o.EmployeeID AND ds.ShipName=o.ShipName AND orderD.datum=DATEADD(dd, 0, DATEDIFF(dd, 0, o.OrderDate)) AND requiredD.datum=DATEADD(dd, 0, DATEDIFF(dd, 0, o.RequiredDate));

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  • LINQ to DataSet Dataclass assignment question

    - by Overhed
    Hi all, I'm working on a Silverlight project trying to access a database using LINQ To DataSet and then sending data over to Silverlight via .ASMX web service. I've defined my DataSet using the Server Explorer tool (dragging and dropping all the different tables that I'm interested in). The DataSet is able to access the server and database with no issues. Below is code from one of my Web Methods: public List<ClassSpecification> getSpecifications() { DataSet2TableAdapters.SpecificationTableAdapter Sta = new DataSet2TableAdapters.SpecificationTableAdapter(); return (from Spec in Sta.GetData().AsEnumerable() select new ClassSpecification() { Specification = Spec.Field<String>("Specification"), SpecificationType = Spec.Field<string>("SpecificationType"), StatusChange = Spec.Field<DateTime>("StatusChange"), Spec = Spec.Field<int>("Spec") }).ToList<ClassSpecification>(); } I created a "ClassSpecification" data class which is going to contain my data and it has all the table fields as properties. My question is, is there a quicker way of doing the assignment than what is shown here? There are actually about 10 more fields, and I would imagine that since my DataSet knows my table definition, that I would have a quicker way of doing the assignment than going field by field. I tried just "select new ClassSpecification()).ToList Any help would be greatly appreciated.

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  • Linq to SQL not inserting data onto the DB

    - by Jesus Rodriguez
    Hello! I have a little / weird behaviour here and Im looking over internet and SO and I didn't find a response. I have to admit that this is my first time using databases, I know how to use them with SQL but never used it actually. Anyway, I have a problem with my app inserting data, I just created a very simple project for testing that and no solution yet. I have an example database with Sql Server Id - int (identity primary key) Name - nchar(10) (not null) The table is called "Person", simple as pie. I have this: static void Main(string[] args) { var db = new ExampleDBDataContext {Log = Console.Out}; var jesus = new Person {Name = "Jesus"}; db.Persons.InsertOnSubmit(jesus); db.SubmitChanges(); var query = from person in db.Persons select person; foreach (var p in query) { Console.WriteLine(p.Name); } } As you can see, nothing extrange. It show Jesus in the console. But if you see the table data, there is no data, just empty. I comment the object creation and insertion and the foreach doesn't print a thing (normal, there is no data in the database) The weird thing is that I created a row in the database manually and the Id was 2 and no 1 (Was the linq really playing with the database but it didn't create the row?) There is the log: INSERT INTO [dbo].Person VALUES (@p0) SELECT CONVERT(Int,SCOPE_IDENTITY()) AS [value] -- @p0: Input NChar (Size = 10; Prec = 0; Scale = 0) [Jesus] -- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.30729.4926 SELECT [t0].[Id], [t0].[Name] FROM [dbo].[Person] AS [t0] -- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.30729.4926 I am really confused, All the blogs / books use this kind of snippet to insert an element to a database. Thank you for helping.

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