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• Losing scope for DataContex using LINQToSQL intermediately

  - by greektreat

  I am having a weird Situation with my DataConext. All My code is in C# I have a DLL project for my data access layer and business Layer which and Winforms project for my UI layer. My Data access Layer's Namespace is xxx.Data this is where have my xxx.dbml I also have xxx.Data.BusinessObjects name space of course for my business object in that project In my UI Layer I have these namespaces xxxApp(for Forms), xxxApp.Controls (For Controls) I have lost scope of the DataContext, it was accessible now when I do a Rebuild Solution I sometimes get compile errors saying for example: Error 34 'xxx.Data.xxxDataContext' does not contain a definition for 'SubmitChanges' and no extension method 'SubmitChanges' accepting a first argument of type 'xxx.Data.xxxDataContext' could be found (are you missing a using directive or an assembly reference?) Also intelisense doesn't recognize the methods and table classes from my xxxDataContext anymore I can access all object fine when I am in the DLL project but now in the Winforms project this is very strange. If anyone can help me out I would be extremely grateful!

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• Updating database row from model

  - by Jamie Dixon

  Hey everyone, I'm haing a few problems updating a row in my database using Linq2Sql. Inside of my model I have two methods for updating and saving from my controller, which in turn receives an updated model from my view. My model methods like like: public void Update(Activity activity) { _db.Activities.InsertOnSubmit(activity); } public void Save() { _db.SubmitChanges(); } and the code in my Controller likes like: [HttpPost] public ActionResult Edit(Activity activity) { if (ModelState.IsValid) { UpdateModel<Activity>(activity); _activitiesModel.Update(activity); _activitiesModel.Save(); } return View(activity); } The problem I'm having is that this code inserts a new entry into the database, even though the model item i'm inserting-on-submit contains a primary key field. I've also tried re-attaching the model object back to the data source but this throws an error because the item already exists. Any pointers in the right direction will be greatly appreciated. UPDATE: I'm using dependancy injection to instantiate my datacontext object as follows: IMyDataContext _db; public ActivitiesModel(IMyDataContext db) { _db = db; }

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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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• Distinct items from IEnumerable< T>

  - by ScG

  I have an IEnumerable< Person object. The Person class has a Designation proeprty. I want to select distinct Designation values from IEnumerable< Person and assign that to a DropDownList. How can I do it?

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• How to return a message from my repository class to my controller and then to my view in asp.net-mvc

  - by Pandiya Chendur

  I use this for checking an existing emailId in my table and inserting it...It works fine how to show message to user when he tries to register with an existing mailId.... if (!taxidb.Registrations.Where(u => u.EmailId == reg.EmailId).Any()) { taxidb.Registrations.InsertOnSubmit(reg); taxidb.SubmitChanges(); } and my controller has this, RegistrationBO reg = new RegistrationBO(); reg.UserName = collection["UserName"]; reg.OrgName = collection["OrgName"]; reg.Address = collection["Address"]; reg.EmailId = collection["EmailId"]; reg.Password = collection["Password"]; reg.CreatedDate = System.DateTime.Now; reg.IsDeleted = Convert.ToByte(0); regrep.registerUser(reg); Any sugesstion how to show "EmailID" already exists to the user with asp.net mvc...

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• Matching on search attributes selected by customer on front end

  - by CodeNinja1974

  I have a method in a class that allows me to return results based on a certain set of Customer specified criteria. The method matches what the Customer specifies on the front end with each item in a collection that comes from the database. In cases where the customer does not specify any of the attributes, the ID of the attibute is passed into the method being equal to 0 (The database has an identity on all tables that is seeded at 1 and is incremental). In this case that attribute should be ignored, for example if the Customer does not specify the Location then customerSearchCriteria.LocationID = 0 coming into the method. The matching would then match on the other attributes and return all Locations matching the other attibutes, example below: public IEnumerable<Pet> FindPetsMatchingCustomerCriteria(CustomerPetSearchCriteria customerSearchCriteria) { if(customerSearchCriteria.LocationID == 0) { return repository.GetAllPetsLinkedCriteria() .Where(x => x.TypeID == customerSearchCriteria.TypeID && x.FeedingMethodID == customerSearchCriteria.FeedingMethodID && x.FlyAblityID == customerSearchCriteria.FlyAblityID ) .Select(y => y.Pet); } } The code for when all criteria is specified is shown below: private PetsRepository repository = new PetsRepository(); public IEnumerable<Pet> FindPetsMatchingCustomerCriteria(CustomerPetSearchCriteria customerSearchCriteria) { return repository.GetAllPetsLinkedCriteria() .Where(x => x.TypeID == customerSearchCriteria.TypeID && x.FeedingMethodID == customerSearchCriteria.FeedingMethodID && x.FlyAblityID == customerSearchCriteria.FlyAblityID && x.LocationID == customerSearchCriteria.LocationID ) .Select(y => y.Pet); } I want to avoid having a whole set of if and else statements to cater for each time the Customer does not explicitly select an attribute of the results they are looking for. What is the most succint and efficient way in which I could achieve this?

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• DataContext to DB

  - by JD

  Hi all, I have designed my DB using the ORM in VS 2008. What is the best way to export this to an SQL server so it will create the tables and relations on SQL Server? Thanks, JD

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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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• Where is the best place to call the .tolist(); inside my controller classes or inside my model repository classes

  - by john G

  I have the following action method, inside my asp.net mvc web application:- public JsonResult LoadZoneByDataCenter(string id) { var zonelist = repository.getrealtedzone(Convert.ToInt32(id)).ToList(); //code goes here Which calls the following model repository method:- public IQueryable<Zone> getrealtedzone(int? dcid) { return tms.Zones.Where(a=> a.DataCenterID == dcid || dcid == null); } Currently I am calling the .tolist() which will interpret the Database from my action method, but my question is where is the best place to call the .tolist() inside the controller or inside the model classes and why ? thanks

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• How cast in c#/.net 3.5 works? for types with '?'

  - by Inez

  This is my code which works public decimal? Get() { var res = ... return res.Count() > 0 ? res.First() : (decimal?) null; } and this one doesn't work public decimal? Get() { var res = ... return res.Count() > 0 ? res.First() : null; } giving the compilator error: Error 1 Type of conditional expression cannot be determined because there is no implicit conversion between 'decimal' and '' I wonder why? any ideas?

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• How does cast in C#/.NET 3.5 work for types with '?'

  - by Inez

  This is my code which works public decimal? Get() { var res = ... return res.Count() > 0 ? res.First() : (decimal?) null; } and this one doesn't work public decimal? Get() { var res = ... return res.Count() > 0 ? res.First() : null; } giving the compiler error: Error 1 Type of conditional expression cannot be determined because there is no implicit conversion between 'decimal' and '<null>' I wonder why? any ideas?

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• How can I find all items beginning with a or â?

  - by Malcolm Frexner

  I have a list of items that are grouped by their first letter. By clicking a letter the user gets alle entries that begin with that letter. This does not work for french. If I choose the letter a, items with â are not returned. What is a good way to return items no matter if they have an accent or not? <% char alphaStart = Char.Parse("A"); char alphaEnd = Char.Parse("Z"); %> <% for (char i = alphaStart; i <= alphaEnd; i++) { %> <% char c = i; %> <% var abcList = Model.FaqList.Where(x => x.CmsHeader.StartsWith(c.ToString())).ToList(); %> <% if (abcList.Count > 0 ) { %> <div class="naviPkt"> <a id="<%= i.ToString().ToUpper() %>" class="naviPktLetter" href="#<%= i.ToString().ToLower() %>"><%= i.ToString().ToUpper() %></a> </div> <ul id="menuGroup<%= i.ToString().ToUpper() %>" class="contextMenu" style="display:none;"> <% foreach (var info in abcList) { %> <li class="<%= info.CmsHeader%>"> <a id="infoId<%= info.CmsInfoId%>" href="#<%= info.CmsInfoId%>" class="abcEntry"><%= info.CmsHeader%></a> </li> <% } %> </ul> <% } %> <% } %>

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• Is using .h as a header for a c++ file wrong?

  - by Chris Huang-Leaver

  Is using .h as a header for a c++ file wrong? I see it all over the place, especially with code written in the "C style". I noticed that Emacs always selects C highlighting style for a .h header, but c++ for hpp or hh. Is it actually "wrong" to label your headers .h or is it just something which annoys me? EDIT: There is a good (ish) reason why this annoys me, if I have project files labelled, 'hpp & cpp' I can get away with 'grep something *pp' etc. otherwise I have to type '.h cpp'

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• Quickly or concisely determine the longest string per column in a row-based data collection

  - by ccornet

  Judging from the failure of my last inquiry, I need to calculate and preset the widths of a set of columns in a table that is being made into an Excel file. Unfortunately, the string data is stored in a row-based format, but the widths must be calculated in a column-based format. The data for the spreadsheets are generated from the following two collections: var dictFiles = l.Items.Cast<SPListItem>().GroupBy(foo => foo.GetSafeSPValue("Category")).ToDictionary(bar => bar.Key); StringDictionary dictCols = GetColumnsForItem(l.Title); Where l is an SPList whose title determines which columns are used. Each SPListItem corresponds to a row of data, which are sorted into separate worksheets based on Category (hence the dictionary). The second line is just a simple StringDictionary that has the column name (A, B, C, etc.) as a key and the corresponding SPListItme field display name as the corresponding value. So for each Category, I enumerate through dictFiles[somekey] to get all the rows in that sheet, and get the particular cell data using SPListItem.Fields[dictCols[colName]]. What I am asking is, is there a quick or concise method, for any one dictFiles[somekey], to retrieve a readout of the longest string in each column provided by dictCols? If it is impossible to get both quickness and conciseness, I can settle for either (since I always have the O(n*m) route of just enumerating the collection and updating an array whenever strCurrent.Length strLongest.Length). For example, if the goal table was the following... Item# Field1 Field2 Field3 1 Oarfish Atmosphere Pretty 2 Raven Radiation Adorable 3 Sunflower Flowers Cute I'd like a function which could cleanly take the collection of items 1, 2, and 3 and output in the correct order... Sunflower, Atmosphere, Adorable Using .NET 3.5 and C# 3.0.

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• Caching stored procedure results in Linq'u

  - by itdebeloper

  In our web application we have a lots of stored procedures look like this one: getSomeData(/* 7 diffrent params */) This stored procedure don't make any updates. We are using Linq'u. I know that the date are changing no often than once per day so the results for the same sets of parameters values will be the same. Does Linqu have cache simple solution? I know how to 'manually' write cache mechanism in .net, but I supposed that in Linqu this problem was solved. I'm a lazy guy :) so I'm looking for something realy simple like: Linqu_global_store_procedure_configuration.CacheDuration="600" Linqu_global_store_procedure_configuration.CacheVaryByParam="*" I'm using .net 3.5 but its not any problem to move for 4.0.

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• asp.net viewdata

  - by mazhar

  public ActionResult AddDinner() { Dinner dinner = dinnerRepository.GetDinner(id); ViewData["dinner"] = repository.AllDinners(); return View(dinner); } 1) First of all both the dinner object and the ViewData["dinner"] is passing to the view? 2) Secondly how would I iterate over the ViewData["dinner"] in the view?

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• [C#] How to create a constructor of a class that return a collection of instances of that class?

  - by codemonkie

  My program has the following class definition: public sealed class Subscriber { private subscription; public Subscriber(int id) { using (DataContext dc = new DataContext()) { this.subscription = dc._GetSubscription(id).SingleOrDefault(); } } } ,where _GetSubscription() is a sproc which returns a value of type ISingleResult<_GetSubscriptionResult> Say, I have a list of type List<int> full of 1000 ids and I want to create a collection of subscribers of type List<Subscriber>. How can I do that without calling the constructor in a loop for 1000 times? Since I am trying to avoid switching the DataContext on/off so frequently that may stress the database. TIA.

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• Is there any extension method which get void returning lamda expression ?

  - by Freshblood

  For example int[] Array = { 1, 23, 4, 5, 3, 3, 232, 32, }; Array.JustDo(x => Console.WriteLine(x));

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• Would you make this method Static or not?

  - by Adam Drummond

  During a code review I presented a method quickly to the team that I had made static and one person agreed that there was no reason for it to not be static and a person disagreed saying that he would not make it static because it wasn't necessary and just to be on the safe side for future modifications and testing. So I did quite a bit of research and obviously it's a specialized case but I would like to know what you would do in this situation and why? (Its basically a helper method I call from a few different methods, a very low traffic page. More for my knowledge and learning on Static.) private IEnumerable<Category> GetCategoryByID(int id, Context context) { var categoryQuery = from selectAllProc in context.SelectAll_sp() where selectAllProc.CategoryID == id select selectAllProc; return categoryQuery; }

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• How can I bind an Enum to a DbType of bit or int?

  - by uriDium

  Hi I am using Linq2Sql and want to bind an objects field (which is enum) to either a bit or a int type in the database. For example I want have a gender field in my model. I have already edited the DBML and changed the Type to point to my enum. I want to create Radio buttons (which I think I have figured out) for gender and dropdown lists for other areas using the same idea. My enum looks like this public enum Gender { Male, Female } Mapping between DbType 'int' and Type 'Project.Models.Gender' in Column 'Gender' of Type 'Candidate' is not supported. Any ideas on how to do this mapping. Am I missing something on the enums.

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

  - by codesmack

  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 <car> and within the car element I need to process the <mileage> 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#

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• Showing multiple models in a single ListView

  - by Veer

  I've three models (Contacts, Notes, Reminders). I want to search all these and produce the filtered result in a single listview and depending upon the selection I've to display the corresponding view(UserControl) to its right. I want the right way of implementing the design or atleast alternatives to this method that I've tried. Now I've tried it using a IntegratedViewModel having all the properties from all the three models. public class IntegratedViewModel { ContactModel _contactModel; NoteModel _noteModel; public IntegratedViewModel(ContactModel contactModel) { _contactModel = contactModel; } // similarly for other models also public string DisplayTitle // For displaying in ListView { get; //same as set set { If(_contactModel != null) return _contactModel.Name; If(_noteModel != null) return _noteModel.Title; } } // All other properties from the three models includin the Name/Title properties for displaying them in the corresponding views(UserControl) } Now I set the itemsSource as the List<IntegratedViewModel>. I've to now bind the visibility of the views to some properties in the MainViewModel. I tried setting bool properties like IsContactViewSelected, IsNoteViewSelected using the setter of SelectedEntity property which is bound to the ListView's SelectedItem. public SelectedEntity { //get set { oldvalue = _selectedEntity; _selectedEntity = value; // now i find the Type of model selected using oldvalue.ModelType // where ModelType is a property in the IntegratedViewModel // according to the type, i set one of the above bool properties to false // and do the same for _selectedEntity but set the property to true // so that the view corresponding to the selectedEntityType is visible // and others are collapsed } } Here is the problem: For eg: let us say, I selected an item of type ContactModel, the old selection being NoteModel. I set the property IsNoteModelSelected to false according to the oldvalue, it sets the property and then Raises the propertychanged event and does not go and check the remaining if condition where i check for _selectedEntity which is used to set the IsContactModelSelected to true.

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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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• Why one loop is performing better than other memory wise as well as performance wise?

  - by Mohit

  I have following two loops in C#, and I am running these loops for a collection with 10,000 records being downloaded with paging using "yield return" First foreach(var k in collection) { repo.Save(k); } Second var collectionEnum = collection.GetEnumerator(); while (collectionEnum.MoveNext()) { var k = collectionEnum.Current; repo.Save(k); k = null; } Seems like that the second loop consumes less memory and it faster than the first loop. Memory I understand may be because of k being set to null(Even though I am not sure). But how come it is faster than for each. Following is the actual code [Test] public void BechmarkForEach_Test() { bool isFirstTimeSync = true; Func<Contact, bool> afterProcessing = contactItem => { return true; }; var contactService = CreateSerivce("/administrator/components/com_civicrm"); var contactRepo = new ContactRepository(new Mock<ILogger>().Object); contactRepo.Drop(); contactRepo = new ContactRepository(new Mock<ILogger>().Object); Profile("For Each Profiling",1,()=>{ var localenumertaor=contactService.Download(); foreach (var item in localenumertaor) { if (isFirstTimeSync) item.StateFlag = 1; item.ClientTimeStamp = DateTime.UtcNow; if (item.StateFlag == 1) contactRepo.Insert(item); else contactRepo.Update(item); afterProcessing(item); } contactRepo.DeleteAll(); }); } [Test] public void BechmarkWhile_Test() { bool isFirstTimeSync = true; Func<Contact, bool> afterProcessing = contactItem => { return true; }; var contactService = CreateSerivce("/administrator/components/com_civicrm"); var contactRepo = new ContactRepository(new Mock<ILogger>().Object); contactRepo.Drop(); contactRepo = new ContactRepository(new Mock<ILogger>().Object); var itemsCollection = contactService.Download().GetEnumerator(); Profile("While Profiling", 1, () => { while (itemsCollection.MoveNext()) { var item = itemsCollection.Current; //if First time sync then ignore and overwrite the stateflag if (isFirstTimeSync) item.StateFlag = 1; item.ClientTimeStamp = DateTime.UtcNow; if (item.StateFlag == 1) contactRepo.Insert(item); else contactRepo.Update(item); afterProcessing(item); item = null; } contactRepo.DeleteAll(); }); } static void Profile(string description, int iterations, Action func) { // clean up GC.Collect(); GC.WaitForPendingFinalizers(); GC.Collect(); // warm up func(); var watch = Stopwatch.StartNew(); for (int i = 0; i < iterations; i++) { func(); } watch.Stop(); Console.Write(description); Console.WriteLine(" Time Elapsed {0} ms", watch.ElapsedMilliseconds); } I m using the micro bench marking, from a stackoverflow question itself benchmarking-small-code The time taken is For Each Profiling Time Elapsed 5249 ms While Profiling Time Elapsed 116 ms

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• Can't delete record via the datacontext it was retrieved from

  - by Antilogic

  I just upgraded one of my application's methods to use compiled queries (not sure if this is relevant). Now I'm getting contradicting error messages when I run the code. This is my method: MyClass existing = Queries.MyStaticCompiledQuery(MyRequestScopedDataContext, param1, param2).SingleOrDefault(); if (existing != null) { MyRequestScopedDataContext.MyClasses.DeleteOnSubmit(existing); } When I run it I get this message: Cannot remove an entity that has not been attached. Note that the compiled query and the DeleteOnSubmit reference the same DataContext. Still I figured I'd humor the application and add an attach command before the DeleteOnSubmit, like so: MyClass existing = Queries.MyStaticCompiledQuery(MyRequestScopedDataContext, param1, param2).SingleOrDefault(); if (existing != null) { MyRequestScopedDataContext.MyClasses.Attach(existing); MyRequestScopedDataContext.MyClasses.DeleteOnSubmit(existing); } BUT... When I run this code, I get a completely different contradictory error message: 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'm at a complete loss... Does anyone else have some insight as to why I can't delete a record via the same DataContext I retrieved it from?

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