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  • How to Solve this Error "Cannot convert lambda expression to type 'string' because it is not a deleg

    - by peace
    . I get this error: "Cannot convert lambda expression to type 'string' because it is not a delegate type" - keyword select become underlined in blue Can you please advice. Employee emp = new Employee(); comHandledBySQt.DataSource = from x in emp.GetDataFromTable("1") select new { x.Id, Name = x.FirstName + " " + x.LastName }; comHandledBySQt.DisplayMember = "Name"; comHandledBySQt.ValueMember = "Id"; Above code should displays drop list of employees first name and last name in a combo box

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  • Handling duplicate insertion

    - by Francis
    So I've got this piece of code which, logically should work but Entity Framework is behaving unexpectedly. Here: foreach (SomeClass someobject in allObjects) { Supplier supplier = new Supplier(); supplier.primary_key = someobject.id; supplier.name = someobject.displayname; try { sm.Add(supplier); ro.Created++; } catch (Exception ex) { ro.Error++; } } Here's what I have in sm.Add() public Supplier Add(Supplier supplier) { try { _ctx.AddToSupplier(supplier); _ctx.SaveChanges(); return supplier; } catch (Exception ex) { throw; } } I can have records in allObjects that have the same id. My piece of code needs to support this and just move on to the next and try to insert it, which I think should work. If this happens, an exception is throw, saying that records with dupe PKs cannot be inserted (of course). The exception mentions the value of the PK, for example 1000. All is well, a new supplier is passed to sm.Add() containing a PK that's never been used before. (1001) Weirdly though, when doing SaveChanges(), EF will whine about not being able to insert records with dupe PKs. The exception still mentions 1000 even though supplier contains 10001 in primary_key. I feel this is me not using _ctx properly. Do I need to call something else to sync it ?

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  • Cannot add an entity that already exists.

    - by mazhar
    Code: public ActionResult Create(Group group) { if (ModelState.IsValid) { group.int_CreatedBy = 1; group.dtm_CreatedDate = DateTime.Now; var Groups = Request["Groups"]; int GroupId = 0; GroupFeature GroupFeature=new GroupFeature(); foreach (var GroupIdd in Groups) { // GroupId = int.Parse(GroupIdd.ToString()); } var Features = Request["Features"]; int FeatureId = 0; int t = 0; int ids=0; string[] Feature = Features.Split(',').ToArray(); //foreach (var FeatureIdd in Features) for(int i=0; i<Feature.Length; i++) { if (int.TryParse(Feature[i].ToString(), out ids)) { GroupFeature.int_GroupId = 35; GroupFeature.int_FeaturesId = ids; if (ids != 0) { GroupFeatureRepository.Add(GroupFeature); GroupFeatureRepository.Save(); } } } return RedirectToAction("Details", new { id = group.int_GroupId }); } return View(); } I am getting an error here Cannot add an entity that already exists. at this line GroupFeatureRepository.Add(GroupFeature); GroupFeatureRepository.Save();

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  • initializing properties with private sets in .Net

    - by Martin Neal
    public class Foo { public string Name { get; private set;} // <-- Because set is private, } void Main() { var bar = new Foo {Name = "baz"}; // <-- This doesn't compile /*The property or indexer 'UserQuery.Foo.Name' cannot be used in this context because the set accessor is inaccessible*/ using (DataContext dc = new DataContext(Connection)) { // yet the following line works. **How**? IEnumerable<Foo> qux = dc.ExecuteQuery<Foo>( "SELECT Name FROM Customer"); } foreach (q in qux) Console.WriteLine(q); } I have just been using the private modifier because it works and kept me from being stupid with my code, but now that I need to create a new Foo, I've just removed the private modifier from my property. I'm just really curious, why does the ExecuteQuery into an IEnumerable of Foo's work?

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  • How can i mock or test my deferred execution functionality?

    - by cottsak
    I have what could be seen as a bizarre hybrid of IQueryable<T> and IList<T> collections of domain objects passed up my application stack. I'm trying to maintain as much of the 'late querying' or 'lazy loading' as possible. I do this in two ways: By using a LinqToSql data layer and passing IQueryable<T>s through by repositories and to my app layer. Then after my app layer passing IList<T>s but where certain elements in the object/aggregate graph are 'chained' with delegates so as to defer their loading. Sometimes even the delegate contents rely on IQueryable<T> sources and the DataContext are injected. This works for me so far. What is blindingly difficult is proving that this design actually works. Ie. If i defeat the 'lazy' part somewhere and my execution happens early then the whole thing is a waste of time. I'd like to be able to TDD this somehow. I don't know a lot about delegates or thread safety as it applies to delegates acting on the same source. I'd like to be able to mock the DataContext and somehow trace both methods of deferring (IQueryable<T>'s SQL and the delegates) the loading so that i can have tests that prove that both functions are working at different levels/layers of the app/stack. As it's crucial that the deferring works for the design to be of any value, i'd like to see tests fail when i break the design at a given level (separate from the live implementation). Is this possible?

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  • What is the correct method to load an XML file and re-write it as a CVS? (C# Only)

    - by codesmack
    Hello, I have a XML file that I want to load into an unknown object type. (I say unknown object type because I am not sure what direction to go) Once I have the data loaded I need to do some processing on certain elements that are now loaded into the new object. For sake of example, we can say that the xml file is full of elements named and within the car element I need to process the element. Then once this is all done I need to write the file as a CSV file. I would like to do this is the most direct way possible. (The less code the better) I am using VS 2008 C# Thank you, CodeSmack

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  • Database cache that I'm not aware of?

    - by Martin
    I'm using asp.net mvc, linq2sql, iis7 and sqlserver express 2008. I get these intermittent server errors, primary key conflicts on insertion. I'm using a different setup on my development computer so I can't debug. After a while they go away. Restarting iis helps. I'm getting the feeling there is cache somewhere that I'm not aware of. Can somebody help me sort out these errors? Cannot insert duplicate key row in object 'dbo.EnquiryType' with unique index 'IX_EnquiryType'. Edits regarding Venemos answer Is it possible that another application is also accessing the same database simultaneously? Yes there is, but not this particular table and no inserts or updates. There is one other table with which I experience the same problem but it has to do with a different part of the model. How often an in what context do you create a new DataContext instance? Only once, using the singleton pattern. Are the primary keys generated by the database or by the application? Database. Which version of ASP.NET MVC and which version of .NET are you using? RC2 and 3.5.

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  • performing more than one Where in query return null!!! why? how to fix this?

    - by Sadegh
    hi, i have wrote a method that filters output with provided query and return it. when one Where excuted; it return correct output but when more than one Where excuted; output is null and Exception occured with message "Enumeration yielded no results". why? how i can fix it? public IQueryable<SearchResult> PerformSearch(string query, int skip = 0, int take = 5) { if (!string.IsNullOrEmpty(query)) { var queryList = query.Split('+').ToList(); var results = GENERATERESULTS(); string key; foreach (string _q in queryList) { if (_q.StartsWith("(") && _q.EndsWith(")")) { key = _q.Replace("(", "").Replace(")", ""); results = results.Where(q => q.Title.Contains(key, StringComparison.CurrentCultureIgnoreCase)); } else if (_q.StartsWith("\"") && _q.EndsWith("\"")) { key = _q.Replace("\"", "").Replace("\"", ""); results = results.Where(q => q.Title.Contains(key, StringComparison.CurrentCulture)); } else if (_q.StartsWith("-(") && _q.EndsWith(")")) { key = _q.Replace("-(", "").Replace(")", ""); results = results.Where(q=> !q.Title.Contains(key, StringComparison.CurrentCultureIgnoreCase)); } else { key = _q; results = results.Where(q => q.Title.Contains(key, StringComparison.CurrentCulture)); } } this._Count = results.Count(); results = results.Skip(skip).Take(take); this._EndOn = DateTime.Now; this.ExecutionTime(); return results; } else return null; } thanks in advance ;)

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  • Lambda expressions and nullable types

    - by Mathew
    I have two samples of code. One works and returns the correct result, one throws a null reference exception. What's the difference? I know there's some magic happening with capturing variables for the lambda expression but I don't understand what's going on behind the scenes here. int? x = null; bool isXNull = !x.HasValue; // this works var result = from p in data.Program where (isXNull) select p; return result.Tolist(); // this doesn't var result2 = from p in data.Program where (!x.HasValue) select p; return result2.ToList();

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  • Textbox is disabled after adding text dynamically in codebehind

    - by user1761348
    Can't quite work out what is happening but The background is that I am dynamically adding table rows in a web page and some of the cells hold controls such as dropdowns etc. One of the columns pulls a size into it. However the column I am having issues with is the next column which takes the text from teh previous dropdown and shows the appropriate price. On doing htis however the textbox which is being created appears to turn into a label as I cannot select or adjust the text that has been put in there. var gotPrice =(from a in getPrice.Sizes where a.Size1 == Size.SelectedValue select a).First(); TextBox Price = new TextBox(); Price.Width = 100; PriceField.Controls.Add(Price); PriceField.Text = gotPrice.RackRate.ToString(); I have tried then calling .Enabled but still the text box is not editable. any help appreciated.

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  • Updating an object with L2S with ASP.NET MVC

    - by Paul
    Is there an easier way to update an object with L2S other then doing it property by property? This is what I am doing now: Public ActionResult Edit(Object obj) { var objToUpdate = _repository.Single<Object>(o => o.id = obj.id); objToUpdate.Prop1 = obj.Prob1; objToUpdate.Prop2 = obj.Prop2; ... _repository.SubmitChanges(); } I am hoping there is a way to just say objToUpdate = obj then submit the changes??? Any help on this would be appreciated!

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  • Interview Question: .Any() vs if (.Length > 0) for testing if a collection has elements

    - by Chris
    In a recent interview I was asked what the difference between .Any() and .Length > 0 was and why I would use either when testing to see if a collection had elements. This threw me a little as it seems a little obvious but feel I may be missing something. I suggested that you use .Length when you simply need to know that a collection has elements and .Any() when you wish to filter the results. Presumably .Any() takes a performance hit too as it has to do a loop / query internally.

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  • Column.DbType affecting runtime behavior

    - by leppie
    Hi According to the MSDN docs, the DbType property/attribute of a Column type/element is only used for database creation. Yet, today, when trying to submit data to an IMAGE column on a SQLCE database (not sure if only on CE), I got an exception of 'Data truncated to 8000 bytes'. This was due to the DbType still being defined as VARBINARY(MAX) which SQLCE does not support. Changing the type to IMAGE in the DbType fixes the issue. So what other surprises does Linq2SQL attributes hold in store? Is this a bug or intended? Should I report it to MS? UPDATE After getting the answer from Guffa, I tested it, but it seems for NVARCHAR(10) adding a 11 char length string causes a SQL exception, and not Linq2SQL one. The data was truncated while converting from one data type to another. [ Name of function(if known) = ] A first chance exception of type 'System.Data.SqlServerCe.SqlCeException' occurred in System.Data.SqlServerCe.dll

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  • How to pass a Lambda Expression as method parameter with EF

    - by Registered User
    How do I pass an EF expression as a method argument? To illustrate my question I have created a pseudo code example: The first example is my method today. The example utilizes EF and a Fancy Retry Logic. What I need to do is to encapsulate the Fancy Retry Logic so that it becomes more generic and does not duplicate. In the second example is how I want it to be, with a helper method that accepts the EF expression as an argument. This would be a trivial thing to do with SQL, but I want to do it with EF so that I can benefit from the strongly typed objects. First Example: public static User GetUser(String userEmail) { using (MyEntities dataModel = new MyEntities ()) { var query = FancyRetryLogic(() => { (dataModel.Users.FirstOrDefault<User>(x => x.UserEmail == userEmail))); }); return query; } } Second Example: T RetryHelper<T>(Expression<Func<T, TValue>> expression) { using (MyEntities dataModel = new (MyEntities ()) { var query = FancyRetryLogic(() => { return dataModel.expression }); } } public User GetUser(String userEmail) { return RetryHelper<User>(<User>.FirstOrDefault<User>(x => x.UserEmail == userEmail)) }

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  • Eager loading in EF1.0

    - by Dave Swersky
    I have a many-to-many relationship: Application - Applications_Servers - Server This is set up in my Entity Data Model and all is well. My problem is that I'd like to eager-load the whole graph of Applications so that I have an IEnumerable<Applications>, each Application member populated with the Servers collection associated by the many-to-many relationship. Normally this wouldn't be a problem, but according to my research there must be a navigation property between Application and Server. This is not the case for me because my Applications_Servers join table has more in it than just the two keys. Therefore, there is no navigation property directly between Application and Server, and this doesn't work: var apps = (from a in context.Application.Include("Server") select a).ToList(); I get an error saying there is no navigation property on Application called "Server", and that's correct, there is none. How do I write the query to eager-load my Applications with their Servers in this case?

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  • Linq2Sql How to write outer join query?

    - by Malcolm
    Hi, I have following SQL tables. ImportantMessages impID Message ImportantMessageUsers imuID imuUserID imuImpID I want to write a Linq2Sql query so that it returns any rows from ImportantMessages that does not have a record in ImportantMessagesUsers. Matchiing fields are impID ----- imuImpID Assume imuUserID of 6

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  • c# finding matching words in table column using Linq2Sql

    - by David Liddle
    I am trying to use Linq2Sql to return all rows that contain values from a list of strings. The linq2sql class object has a string property that contains words separated by spaces. public class MyObject { public string MyProperty { get; set; } } Example MyProperty values are: MyObject1.MyProperty = "text1 text2 text3 text4" MyObject2.MyProperty = "text2" For example, using a string collection, I pass the below list var list = new List<>() { "text2", "text4" } This would return both items in my example above as they both contain "text2" value. I attempted the following using the below code however, because of my extension method the Linq2Sql cannot be evaluated. public static IQueryable<MyObject> WithProperty(this IQueryable<MyProperty> qry, IList<string> p) { return from t in qry where t.MyProperty.Contains(p, ' ') select t; } I also wrote an extension method public static bool Contains(this string str, IList<string> list, char seperator) { if (String.IsNullOrEmpty(str) || list == null) return false; var splitStr = str.Split(new char[] { seperator }, StringSplitOptions.RemoveEmptyEntries); foreach (string s in splitStr) foreach (string l in list) if (String.Compare(s, l, true) == 0) return true; return false; } Any help or ideas on how I could achieve this?

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  • Updating Many-to-Many relationship with LinqToSQL

    - by Noffie
    If I had, for example, a Many-to-Many mapping table called "RolesToUsers" between a Users and an Roles table, here is how I do it: // DataContext is db, usr is a User entity // newUserRolesMappings is a collection with the desired new mappings, probably // derived by looking at selections in a checkbox list of Roles on a User Edit page db.RolesToUsers.DeleteAllOnSubmit(usr.RolesToUsers); usr.RolesToUsers.Clear(); usr.RolesToUsers.AddRange(newUserRolesMappings); I used the SQL profiler once, and this seems to generate very intelligent SQL - it will only drop the rows which are no longer in the mapping relationship, and only add rows which did not already exist in the relationship. It doesn't blindly do a complete clearing and re-construction of the relationship, as I thought it would. The internet is surprisingly quiet on the subject, and the query "LinqToSQL many-to-many" mostly just turns up articles about how the LinqToSQL data mapper doesn't "support" it very well. How does everyone else update many-to-many with LinqToSQL?

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  • Linq2Entities: Update relationship?

    - by Poku
    Hey, How do i create a new row in a table which have a relationship with another table? I have an Employees table and a EmployeeProjects table. One Employee can have 1-* EmployeeProjects. Now i want to create a new EmployeeProject which relates to an Employee. How do i do this? Here is want i have tried so far: var ep = new EmployeeProjects(); ep.JobNo = jobNo; employee.EmployeeProjects.Add(ep); var originalEmployee = GetEmployee(employee.Id); _entities.ApplyPropertyChanges(originalEmployee.EntityKey.EntitySetName, employee); _entities.SaveChanges();

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  • Question about the ITextUndoHistory that gets returned from TryGetHistory

    - by Nick U
    Everytime the IWpfTextView's TextBuffer changes I am trying to get the history's redostack and undostack and simply checking the count. When doing this I am encountering a "Method not supported exception" when trying to access the two stacks. Am I retrieving the history incorrectly or does VS not want me seeing/editing the contents of the stacks? I can post the code if necessary... Thanks, Nick

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  • Beginner Question on traversing a EF4 model

    - by user564577
    I have a basic EF4 model with two entities. I'm using Self Tracking Entities Client has ClientAddresses relationship on clientkey = clientkey. (1 to many) How do i get a list/collection of client entities (STE) and their addresses (STE) but only ones where they live in a particular state or some such filter on the address??? This seems to filter and bring back clients but doesnt bring back addresses. var j = from client in context.Clients where client.ClientAddresses.All(c => c.ZIP == "80923") select client; I cant get this to create the Addresses because ClientAddresses is IEnumerable and it needs a TrackableCollection var query = from t1 in context.Clients join t2 in context.ClientAddresses on t1.ClientKey equals t2.ClientKey where t2.ZIP == "80923" select new Client { FirstName = t1.FirstName, LastName = t1.LastName, IsEnabled = t1.IsEnabled, ClientKey = t1.ClientKey, ChangeUser = t1.ChangeUser, ChangeDate = t1.ChangeDate, ClientAddresses = from a in t1.ClientAddresses select new ClientAddress { AddressKey = a.AddressKey, AddressLine1 = a.AddressLine1, AddressLine2 = a.AddressLine2, AddressTypeCode = a.AddressTypeCode, City = a.City, ClientKey = a.ClientKey, State = a.State, ZIP = a.ZIP } }; Any pointers would be appreciated. Thanks Edit: This seems to work.... var j = from client in context.Clients.Include("ClientAddresses") where client.ClientAddresses.Any(c => c.ZIP == "80923") select client;

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  • Use DataContext to create schema in an existing blank database file?

    - by jdk
    With a DataContext and a blank file-based database that already exists, is it possible to write the Data Context classes (i.e. the ones I added to the designer) to create the db schema? With a data context I only see the abilities to either: create a new database file and have its structure created at the same time, or to populate data into an existing database having preexisting schema. I'm looking for a hybrid solution between those two worlds. Update 1: My proof that a preexisting db is not compatible with the Data Context CreateDatabase() operation is this error Database 'C:...\App_Data\IntermediateData.mdf' already exists. Choose a different database name. based on this code using (IntermediateClassesDataContext intermediateContext = new IntermediateClassesDataContext(_getIntermediateConn())) { intermediateContext.CreateDatabase(); }

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  • StreamInsight complex query with filter on HoppingWindow

    - by hh354
    I'm trying out StreamInsight and I came across a problem with a query I need. I'm trying to throw a warning if there are several changes in my measured values (of up to 20% change) in the last 30 minutes. This is the query I came up with for now but it isn't working and it's not even correct I think. Apparently I can't filter on a window...? var deviationQuery = from s in wcfStream group s by s.SensorId into grouped from window in grouped.HoppingWindow(TimeSpan.FromMinutes(30),TimeSpan.FromMinutes(1)) where window.StdDev(e => e.Value) > measurableValue * 1.2 select new OutputEvent { Error = "Deviation" }; Thanks in advance!

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  • How to perform a select using a WHERE NOT EXISTS

    - by Peter Bridger
    I'm using LINQ2SQL and I want to compare two tables and select all rows that are missing from one tables (based upon one of the column values). In standard SQL I would write this as: SELECT FirstName, LastName, RefId, Email FROM Users_ActiveDirectory AS ADU WHERE NOT EXISTS ( SELECT U.RefId FROM Users AS U WHERE U.RefID = ADU.RefId ) However I'm not sure how to achieve the same result using LINQ2SQL?

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