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  • Cannot implicitly convert type 'System.Linq.IQueryable<int>' to 'int?'

    - by Aneef
    Hi this is my code var cityList = from country in doc.Element("result").Element("cities").Descendants("city") select new { Name = country.Element("name").Value, Code = country.Element("code").Value, CountryCode = int.Parse(country.Element("countrycode").Value) }; foreach(var citee in cityList) { City city = new City(); city.CountryID = from cnt in db.Countries where cnt.DOTWInternalID == citee.CountryCode select cnt.ID; } Im getting an error on the second query as the title of this post, i tried converting to int, to nullable int nothing worked? help me guys Thanks,

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  • How to implement paging for datagrid using LINQ to Entities in wpf?

    - by Levelbit
    I'm new in wpf. My main problem is to understand how DataGrid works with its datacontext. It would help me a lot because I don't know how to make a universal paging usercontrol for all my datagrids in the projects for different database tables. DataGrid converts received DataContext from object to some kind of list. How it is implemented. I tried to do some casting from object to IQueryable to generalize thinig because base class of every entity in the entity model is EntityObject class. But it doesen't work in runtime although I don't receive complains at design time.

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  • Linq 2 SQL One to Zero or One relationship possible?

    - by Mr. Flibble
    Is it possible to create a one to zero or one relationship in Linq2SQL? My understanding is that to create a one to one relationship you create a FK relationship on the PK of each table. But you cannot make the PK nullable, so I don't see how to make a one to zero or one relationship work? I'm using the designer to automatically create the model - so I would like to know how to set up the SQL tables to induce the relationship - not some custom ORM code.

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  • How to mass insert/update in linq to sql?

    - by chobo2
    Hi How can I do these 2 scenarios. Currently I am doing something like this public class Repository { private LinqtoSqlContext dbcontext = new LinqtoSqlContext(); public void Update() { // find record // update record // save record ( dbcontext.submitChanges() } public void Insert() { // make a database table object ( ie ProductTable t = new ProductTable() { productname ="something"} // insert record ( dbcontext.ProductTable.insertOnSubmit()) // dbcontext.submitChanges(); } } So now I am trying to load an XML file what has tons of records. First I validate the records one at a time. I then want to insert them into the database but instead of doing submitChanges() after each record I want to do a mass submit at the end. So I have something like this public class Repository { private LinqtoSqlContext dbcontext = new LinqtoSqlContext(); public void Update() { // find record // update record } public void Insert() { // make a database table object ( ie ProductTable t = new ProductTable() { productname ="something"} // insert record ( dbcontext.ProductTable.insertOnSubmit()) } public void SaveToDb() { dbcontext.submitChanges(); } } Then in my service layer I would do like for(int i = 0; i < 100; i++) { validate(); if(valid == true) { update(); insert() } } SaveToDb(); So pretend my for loop is has a count for all the record found in the xml file. I first validate it. If valid then I have to update a table before I insert the record. I then insert the record. After that I want to save everything in one go. I am not sure if I can do a mass save when updating of if that has to be after every time or what. But I thought it would work for sure for the insert one. Nothing seems to crash and I am not sure how to check if the records are being added to the dbcontext.

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  • Linq to SQL DynamicInvoke(System.Object[])' has no supported translation to SQL.

    - by ewwwyn
    I have a class, Users. Users has a UserId property. I have a method that looks something like this: static IQueryable<User> FilterById(this IQueryable<User> p, Func<int, bool> sel) { return p.Where(m => sel(m)); } Inevitably, when I call the function: var users = Users.FilterById(m => m > 10); I get the following exception: Method 'System.Object DynamicInvoke(System.Object[])' has no supported translation to SQL. Is there any solution to this problem? How far down the rabbit hole of Expression.KillMeAndMyFamily() might I have to go? To clarify why I'm doing this: I'm using T4 templates to autogenerate a simple repository and a system of pipes. Within the pipes, instead of writing: new UserPipe().Where(m => m.UserId > 10 && m.UserName.Contains("oo") && m.LastName == "Wee"); I'd like to generate something like: new UserPipe() .UserId(m => m > 10) .UserName(m => m.Contains("oo")) .LastName("Wee");

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  • How to group a complex list of objects using LINQ?

    - by Daoming Yang
    I want to select and group the products, and rank them by the number of times they occur. For example, I have an OrderList each of order object has a OrderProductVariantList(OrderLineList), and each of OrderProductVariant object has ProductVariant, and then the ProductVariant object will have a Product object which contains product information. A friend helped me with the following code. It could be compiled, but it did not return any value/result. I used the watch window for the query and it gave me "The name 'query' does not exist in the current context". Can anyone help me? Many thanks. var query = orderList.SelectMany( o => o.OrderLineList ) // results in IEnumerable<OrderProductVariant> .Select( opv => opv.ProductVariant ) .Select( pv => p.Product ) .GroupBy( p => p ) .Select( g => new { Product = g.Key, Count = g.Count() });

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  • Index was outside the bounds of the array. IndexOutOfRangeException in LINQ to SQL

    - by gtas
    Im getting this exception in the protected virtual void SendPropertyChanged(String propertyName) { if ((this.PropertyChanged != null)) { this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); <---- HERE !!! } } of one recently table association i created, there lots of same associations around the database, and this happened in the 4 specific tables i added. Its 1...* relationship and association is Primary Table - Id (identity auto generated) Foreign PId column int not null. I just dont get it....Im using SqlMetal for generation, i regenerated the schema, rebuild, same. This is causing while inserting row in DevExpress XtraGrid, but i dont think this should be issue, same control with same functionality but for different tables works ok. I use grid's event for append value in a property when the entity creating. I disabled this but same again. Recreated the association. No change, exception occurs. Any ideas?

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  • How to avoid "source !=null" when using Code Contracts and Linq To Sql?

    - by Florian
    I have the following code using a normal data context which works great: var dc = new myDataContext(); Contract.Assume(dc.Cars!= null); var cars = (from c in dc.Cars where c.Owner = 'Jim' select c).ToList(); However when I convert the filter to an extension method like this: var dc = new myDataContext(); Contract.Assume(dc.Cars!= null); var cars = dc.Cars.WithOwner('Jim'); public static IQueryable<Car> WithOwner(IQueryable<Car> cars, string owner) { Contract.Requires(cars != null); return cars.Where(c => c.Owner = owner); } I get the following warning: warning : CodeContracts: requires unproven: source != null

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  • 'Invalid column name [ColumnName]' on a nested linq query.

    - by Joe
    I've got the following query: ATable .GroupBy(x=> new {FieldA = x.FieldAID, FieldB = x.FieldBID, FieldC = x.FieldCID}) .Select(x=>new {FieldA = x.Key.FieldA, ..., last_seen = x.OrderByDescending(y=>y.Timestamp).FirstOrDefault().Timestamp}) results in: SqlException: Invalid column name 'FieldAID' x 5 SqlException: Invalid column name 'FieldBID' x 5 SqlException: Invalid column name 'FieldCID' x 1 I've worked out it has to do with the last query to Timestamp because this works: ATable .GroupBy(x=> new {FieldA = x.FieldAID, FieldB = x.FieldBID, FieldC = x.FieldCID}) .Select(x=>new {FieldA = x.Key.FieldA, ..., last_seen = x.OrderByDescending(y=>y.Timestamp).FirstOrDefault()}) The query has been simplified. The purpose is to group by a set of variables and then show the last time this grouping occured in the db. I'm using Linqpad 4 to generate these results so the Timestamp gives me a string whereas FirstOrDefault gives me the whole object which isn't ideal. Update On further testing I've noticed that the number and type of SQLException is related to the class created in the groupby clause. So, ATable .GroupBy(x=> new {FieldA = x.FieldAID}) .Select(x=>new {FieldA = x.Key.FieldA, last_seen = x.OrderByDescending(y=>y.Timestamp).FirstOrDefault()}) results in SqlException: Invalid column name 'FieldAID' x 5

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  • Linq to find pair of points with longest length?

    - by Chris
    I have the following code: foreach (Tuple<Point, Point> pair in pointsCollection) { var points = new List<Point>() { pair.Value1, pair.Value2 }; } Within this foreach, I would like to be able to determine which pair of points has the most significant length between the coordinates for each point within the pair. So, let's say that points are made up of the following pairs: (1) var points = new List<Point>() { new Point(0,100), new Point(100,100) }; (2) var points = new List<Point>() { new Point(150,100), new Point(200,100) }; So I have two sets of pairs, mentioned above. They both will plot a horizontal line. I am interested in knowing what the best approach would be to find the pair of points that have the greatest distance between, them, whether it is vertically or horizontally. In the two examples above, the first pair of points has a difference of 100 between the X coordinate, so that would be the point with the most significant difference. But if I have a collection of pairs of points, where some points will plot a vertical line, some points will plot a horizontal line, what would be the best approach for retrieving the pair from the set of points whose difference, again vertically or horizontally, is the greatest among all of the points in the collection? Thanks! Chris

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  • Can I check wheter Linq 2 SQL's DataContext is tracking entities?

    - by Thomas Jespersen
    We want to throw an exception, if a user calls DataContext.SubmitChanges() and the DataContext is not tracking anything. That is... it is OK to call SubmitChanges if there are no inserts, updates or deletes. But we want to ensure that the developer didn't forget to attach the entity to the DataContext. Even better... is it possible to get a collection of all entities that the DataContext is tracking (including those that are not changed)? PS: The last question I asked were answered with: "do it this way instead"... please don't :-)

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  • c# and linq: want {1,1,2,3} == {1,2,3,1} returns true but {1,1,2,3} == {1,2,3} returns false

    - by dFlat
    I have two sets, both IEnumerables, and I want to compare them. string[] names1 = { "tom", "dick", "harry" }; string[] names2 = { "tom", "dick", "harry", "harry"}; string[] names3 = { "tom", "dick", "harry", "sally" }; string[] names4 = { "dick", "harry", "tom" }; Want names1 == names4 to return true (and self == self returns true obviously) But all other combos return false. What is the most efficient way? These can be large sets of complex objects. I looked at doing: var a = name1.orderby<MyCustomType, string>(v => v.Name); var b = name4.orderby<MyCustomType, string>(v => v.Name); return a == b;

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  • How do I add ROW_NUMBER to a LINQ query or Entity?

    - by Whozumommy
    I'm stumped by this easy data problem. I'm using the Entity framework and have a database of products. My results page returns a paginated list of these products. Right now my results are ordered by the number of sales of each product, so my code looks like this: return Products.OrderByDescending(u => u.Sales.Count()); This returns an IQueryable dataset of my entities, sorted by the number of sales. I want my results page to show the rank of each product (in the dataset). My results should look like this: Page #1 1. Bananas 2. Apples 3. Coffee Page #2 4. Cookies 5. Ice Cream 6. Lettuce I'm expecting that I just want to add a column in my results using the SQL ROW_NUMBER variable...but I don't know how to add this column to my results datatable. My resulting page does contain a foreach loop, but since I'm using a paginated set I'm guessing using that number to fake a ranking number would NOT be the best approach. So my question is, how do I add a ROW_NUMBER column to my query results in this case?

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  • I'm trying to handle the updates on 2 related tables in one DetailsView using Jquery and Linq, and h

    - by Ben Reisner
    Given two related tables (reports, report_fields) where there can be many report_fields entries for each reports entry, I need to allow the user to enter new report_fields, delete existing report_fields, and re-arrange the order. Currently I am using a DetailsView to handle the editing of the reports. I added some logic to handle report_fields, and currently it allows you to succesfully re-arrange the order, but i'm a little stumped as to the best way to add new items, or delete existing items. The basic logic I have is that each report_fields is represented by a . It has a description as the text, and a field for each field in the report_fields table. I use JQuery Sortable to allow the user to re-arrange the LIs. Abbreviated Create Table Statements:(foreign key constraint ignored for brevity) create table report( id integer primary key identity, reportname varchar(250) ) create table report_fields( id integer primary key identity, reportID integer, keyname integer, keyvalue integer, field_order integer ) My abbreviated markup: <asp:DetailsView ...> ... <asp:TemplateField HeaderText="Fields"> <EditItemTemplate> <ul class="MySortable"> <asp:Repeater ID="Repeater1" runat="server" DataSource='<%# Eval("report_fields") %>'> <ItemTemplate> <li> <%# Eval("keyname") %>: <%# Eval("keyvalue") %> <input type="hidden" name="keyname[]" value='<%# Eval("keyname") %>' /> <input type="hidden" name="keyvalue[]" value='<%# Eval("keyvalue") %>' /> </li> </ItemTemplate> </asp:Repeater> </ul> </EditItemTemplate> </asp:TemplateField> </asp:DetailsView> <asp:LinqDataSource ID="LinqDataSource2" onupdating="LinqDataSource2_Updating" table=reports ... /> $(function() { $(".MySortable").sortable({ placeholder: 'MySortable-highlight' }).disableSelection(); }); Code Behind Class: public partial class Administration_AddEditReport protected void LinqDataSource2_Updating(object sender, LinqDataSourceUpdateEventArgs e) { report r = (report)e.NewObject; MyDataContext dc = new MyDataContext(); var fields = from f in dc.report_fields where f.reportID == r.id select f; dc.report_fields.DeleteAllOnSubmit(fields); NameValueCollection nvc = Request.Params; string[] keyname = nvc["keyname[]"].Split(','); string[] keyvalue = nvc["keyvalue[]"].Split(','); for (int i = 0; i < keyname.Length; i++) { report_field rf = new report_field(); rf.reportID = r.id; rf.keyname = keyname[i]; rf.keyvalue = keyvalue[i]; rf.field_order = i; dc.report_fields.InsertOnSubmit(rf); } dc.SubmitChanges(); } }

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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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  • Is this Where condition in Linq-to-sql join correct?

    - by Pandiya Chendur
    I have the following Iqueryable method to show details of a singl material, public IQueryable<Materials> GetMaterial(int id) { return from m in db.Materials join Mt in db.MeasurementTypes on m.MeasurementTypeId equals Mt.Id where m.Mat_id equals id select new Materials() { Id = Convert.ToInt64(m.Mat_id), Mat_Name = m.Mat_Name, Mes_Name = Mt.Name, }; } Any suggestion....

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  • How do you compare dates in a LINQ query?

    - by Gina
    I am tring to compare a date from a asp calendar control to a date in the table.... here's what i have... it doesn't like the == ? var query = from details in db.TD_TravelCalendar_Details where details.StartDate == calStartDate.SelectedDate && details.EndDate == calEndDate.SelectedDate select details;

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  • LINQ to SQL: ExecuteQuery not working when performing a parameterized query.

    - by ajbeaven
    I have a weird problem with ExecuteQuery in that it isn't working when performing a parameterized query. The following returns 1 record: db.ExecuteQuery<Member>(@"SELECT * FROM Member INNER JOIN aspnet_Users ON Member.user_id = aspnet_Users.UserId WHERE [aspnet_Users].[UserName] = 'Marina2'"); However, the parameterized version returns no results: db.ExecuteQuery<Member>(@"SELECT * FROM Member INNER JOIN aspnet_Users ON Member.user_id = aspnet_Users.UserId WHERE [aspnet_Users].[UserName] = '{0}'", "Marina2"); What am I doing wrong?

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  • What is the best way in assigning foreign key when using entity framework & LINQ to Entities?

    - by Abdel Olakara
    Hi all, I need to know the best practice of creating an entity object and assigning the foreign key. Here is my scenario. I have a Product table with pid,name,unit_price etc.. I also have a Rating table with pid (foregin key),rate,votes etc... Currently i am doing the following to create the rating object: var prod = entities.Product.First(p => p.product_id == pid); prod.Rating.Load(); if (prod.Rating != null) { log.Info("Rating already exists!"); // set values and Calcuate the score } else { log.Info("New Rating!!!"); Rating rating = new Rating(); // set values and do inital calculation prod.Rating = rating; } entities.SaveChanges(); Even though this works fine, i would like to know the best practice in doing these kind of assignment. Thanks for your suggestions and info. Best Regards, Abdel Olakara

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  • LINQ: why does this query not work on an ArrayList?

    - by Benny
    public static ArrayList GetStudentAsArrayList() { ArrayList students = new ArrayList { new Student() { RollNumber = 1,Name ="Alex " , Section = 1 ,HostelNumber=1 }, new Student() { RollNumber = 2,Name ="Jonty " , Section = 2 ,HostelNumber=2 } }; return students; } The following code doesn't compile. The error is ArrayList is not IEnumerable ArrayList lstStudents = GetStudentAsArrayList(); var res = from r in lstStudents select r; This compiles: ArrayList lstStudents = GetStudentAsArrayList(); var res = from Student r in lstStudents select r; Can anybody explain what the difference is between these two snippets? Why the second works?

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  • An attempt has been made to Attach or Add an entity that is not new Linq to Sql error

    - by Collin Oconnor
    I have a save function for my order entity that looks like this and it breaks on the sumbmitChanges line: public void SaveOrder ( Order order ) { if (order.OrderId == 0) orderTable.InsertOnSubmit(order); else if (orderTable.GetOriginalEntityState(order) == null) { orderTable.Attach(order); orderTable.Context.Refresh(RefreshMode.KeepCurrentValues , order); } orderTable.Context.SubmitChanges(); } The order entity contains two other entities; an Address entity and a credit card entity. Now i want these two entities to be null sometimes. Now my guess for why this is throwing an error is because that both of these entites that are inside order are null. If this is the case, How can I insert an new order into the database with both entities (Address and creditCard) being null.

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  • Locked DataGridView. Linq is a problem ?

    - by phenevo
    Hi, I get the collection from webservice: var allPlaceHolders = (from ph in new MyService().GetPlaceHolders() select ph).Select(l => new { Code = l.Code, Name = l.Name, Related = false }).ToList(); dgPlaceHoldersAdd.DataSource = allPlaceHolders; Designer.cs: this.dgPlaceHoldersAdd.ColumnHeadersHeightSizeMode = System.Windows.Forms.DataGridViewColumnHeadersHeightSizeMode.AutoSize; this.dgPlaceHoldersAdd.Location = new System.Drawing.Point(3, 54); this.dgPlaceHoldersAdd.Name = "dgPlaceHoldersAdd"; this.dgPlaceHoldersAdd.RowHeadersVisible = false; this.dgPlaceHoldersAdd.Size = new System.Drawing.Size(286, 151); this.dgPlaceHoldersAdd.TabIndex = 15; The problem is, that I can't changing value of checkBox column. I has enabled AutoGeneratedColumns (In datagridview at start there is not any column)

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