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  • How to test a lamda expression var query result is null?

    - by mike
    var query = from emp in dbEmp.Employees join dept in dbEmp.Departments on emp.DeptID equals dept.DeptID where dept.DepartmentName.Contains(this.TextBox1.Text) select new { EmpID = emp.EmpID, EmpName = emp.EmpName, Age = emp.Age, Address = emp.Address, DeptName = dept.DepartmentName }; if (query==null) Label1.Text = "no results match your search"; GridView1.DataSource = query; GridView1.DataBind(); Everything works in the right way, but the label doesn't show the message when query result returns null. The label can show without condition(querry==null). So how to test if a var query result returns nothing? Thanks

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  • Problem Writing Linq2Xml Query

    - by Gavin Draper
    I'm trying to write a Linq2XML query to query the following XML. I need it to pull back all photos for a given GalleryID. <Albums> <Album GalleryId="1" Cover="AlbumCover1.jpg" Title="Album 1"> <Photos> <Photo Title="Image1" URL="img1.jpg" DateAdded="01/01/2010 09:20"/> <Photo Title="Image2" URL="img2.jpg" DateAdded="01/01/2010 09:20"/> <Photo Title="Image3" URL="img3.jpg" DateAdded="01/01/2010 09:20"/> </Photos> </Album> <Album GalleryId="2" Cover="AlbumCover1.jpg" Title="Album 2"> <Photos> <Photo Title="Image1" URL="img1.jpg" DateAdded="01/01/2010 09:20"/> <Photo Title="Image2" URL="img2.jpg" DateAdded="01/01/2010 09:20"/> </Photos> </Album> </Albums> The best I've come up with is XDocument xmlDoc = XDocument.Load(GalleryFilePath); var x = from c in xmlDoc.Descendants("Album") where c.Attribute("GalleryId").Equals(GalleryId) orderby c.Attribute("Title").Value descending select new { Title = c.Element("Photo").Attribute("Title"), URL = c.Element("Photo").Attribute("URL"), DateAdded = c.Element("Photo").Attribute("DateAdded") }; This returns nothing, I'm guessing this is because I'm telling it to query the Album element then trying to loop through the photo elements. Any tips as to how this should be done? Thanks

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  • Entity Date Modelset Generates Errors in Visual Web Developer

    - by davemackey
    I attempted to add a ADO.NET Entity Data Model to my Visual Web Developer 2010 Express project and it generates but returns a whole slew of errors. Why is this generating errors? Here are the main errors: 'Public Property ID As Integer' has multiple definitions with identical signatures. Method 'Onaddress_IDChanging' cannot be declared 'Partial' because only one method 'Onaddress_IDChanging' can be marked 'Partial'. '_line1' is already declared as 'Private _line1 As String' in this class.

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  • mvc fill dropdownlist

    - by user276640
    i use this code to fill dropdownlist ViewData["projectType"] = new SelectList(_dataManager.Project.ProjectTypeList(), "Id", "Name"); but what i must do if i want to use not one table column but two or more columns? for example ViewData["projectType"] = new SelectList(_dataManager.Project.ProjectTypeList(), "Id", "Name1"+"Name2");

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  • How do I simulate "Is In" using Linq2Sql

    - by flipdoubt
    I often find myself with a list of disconnected Linq2Sql objects or keys that I need to re-select from a Linq2Sql data-context to update or delete in the database. If this were SQL, I would use IS IN in the SQL WHERE clause, but I am stuck with what to do in Linq2Sql. Here is a sample of what I would like to write: public void MarkValidated(IList<int> idsToValidate) { using(_Db.NewSession()) // Instatiates new DataContext { // ThatAreIn <- this is where I am stuck var items = _Db.Items.ThatAreIn(idsToValidate).ToList(); foreach(var item in items) item.Validated = DateTime.Now; _Db.SubmitChanges(); } // Disposes of DataContext } Or: public void DeleteItems(IList<int> idsToDelete) { using(_Db.NewSession()) // Instatiates new DataContext { // ThatAreIn <- this is where I am stuck var items = _Db.Items.ThatAreIn(idsToValidate); _Db.Items.DeleteAllOnSubmit(items); _Db.SubmitChanges(); } // Disposes of DataContext } Can I get this done in one trip to the database? If so, how? Is it possible to send all those ints to the database as a list of parameters and is that more efficient than doing a foreach over the list to select each item one at a time?

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  • Is there an easy way to compare if 2 XDocuments are equal ignoring element/attribute order?

    - by Davy8
    Unit testing my serialization code I found one failed because I had attributes listed in a different order (I'm just comparing the XDocument.ToString() values) and while I could fix that, it really doesn't matter to me in what order the elements or attributes appear as long as they're all there with the right name at the right level of hierarchy. I could probably write a method do this, but I'm wondering if there's an easy built in way I'm not aware of.

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  • Linqify this: Aggregate a subset of a list

    - by JMarsch
    Suppose I have a list or array of items, and I want to sum a subset of the items in the list. (in my case, it happens to always be a sequential subset). Here's the old-fashioned way: int sum = 0; for(int i = startIndex; i <= stopIndex; i++) sum += myList[i].TheValue; return sum; What's the best way to linqify that code?

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  • GetRolesForUser tries to get Roles on old username?

    - by Xaisoft
    I have a section on a page where a user can change their username. This is basically the code for that: user.UserName = txtNewUserName.Text; user.Save(); user is a class in my dbml and Save calls SubmitChanges on the data context. The name is changed in the database, so when it calls the following method, it fails because it is trying to get the user with the old username instead of the one that is in the database now. public override string[] GetRolesForUser(string username) { return dc.Users.Where(u => u.UserName== username) .SingleOrDefault().Roles .Select(r => r.RoleName).ToArray<string>(); }

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  • C# XElement: Node Formatting with HTML

    - by Arnej65
    I'm extracting XML node from an XElement. When I use XElement.Value it strips any HTML that may be in the node. I know that if I do XElement.ToString() I can keep the HTML, but it also gives me the node tags. Is there any way to extract the content of a Node as is without the HTML being stripped out? Cheers.

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  • ASP.NET GridView Sort?

    - by Curtis White
    I'm performing a query with a sort in the Selecting event of the LinqDataSource. I'm then casting my query to a list and assigning it to the result. I'm using this data source in an ASP.NET gridview. I can see the list is sorted but when the ASP.NET gridview does not seem to be respecting the sort order. How can I get the gridview to respect my default sort order?

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  • Precompile Lambda Expression Tree conversions as constants?

    - by Nathan
    It is fairly common to take an Expression tree, and convert it to some other form, such as a string representation (for example this question and this question, and I suspect Linq2Sql does something similar). In many cases, perhaps even most cases, the Expression tree conversion will always be the same, i.e. if I have a function public string GenerateSomeSql(Expression<Func<TResult, TProperty>> expression) then any call with the same argument will always return the same result for example: GenerateSomeSql(x => x.Age) //suppose this will always return "select Age from Person" GenerateSomeSql(x => x.Ssn) //suppose this will always return "select Ssn from Person" So, in essence, the function call with a particular argument is really just a constant, except time is wasted at runtime re-computing it continuously. Assuming, for the sake of argument, that the conversion was sufficiently complex to cause a noticeable performance hit, is there any way to pre-compile the function call into an actual constant?

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  • How can i return IEnumarable data from function in GridView with Entity FrameWork?

    - by programmerist
    protected IEnumerable GetPersonalsData() { // List personel; using (FirmaEntities firmactx = new FirmaEntities()) { var personeldata = (from p in firmactx.Personals select new { p.ID, p.Name, p.SurName }); return personeldata.AsEnumerable(); } } i wan to send GetPersonelData() into GridView DataSource. Like That: gwPersonel.DataSource = GetPersonelData(); gwPersonel.DataBind(); it monitored to me on : gwPersonel.DataBind(); this error: "The ObjectContext instance has been disposed and can no longer be used for operations that require a connection."

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  • Liqn to sql null-able value in query

    - by msony
    I need get all items what have no categories int? categoryId = null; var items=db.Items.Where(x=>x.CategoryId==categoryId); this code generate in where: where CategoryId=null instead of where CategoryId is null ok, when i write var items=db.Items.Where(x=>x.CategoryId==null); in my sql profiler it works: where CategoryId is null BUT when i do this HACK it doesn't: var items=db.Items.Where(x=>x.CategoryId==(categoryId.HasValue ? categoryId : null)); so what's the problem? is there by in L2S?

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  • linq2sql and multiple joins

    - by zerkms
    is it possible to do multiple joins: from g in dataContext.Groups join ug in dataContext.UsersGroups on g.Id equals ug.GroupId join u in dataContext.Users on u. where ug.UserId == user.Id select GroupRepository.ToEntity(g); in the sample above all is fine until i press "." in the end of the 3rd line. there i expect to get intellisense and write u.Id == ug.UserId but it doesn't appear. and of course this code doesn't compile after. what did i wrong?

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  • If I select from an IQueryable then the Include is lost

    - by Connor Murphy
    The include does not work after I perform a select on the IQueryable query. Is there a way arround this? My query is public IQueryable<Network> GetAllNetworks() { var query = (from n in _db.NetworkSet .Include("NetworkContacts.Contact") .Include("NetworkContacts.Contact.RelationshipSource.Target") .Include("NetworkContacts.Contact.RelationshipSource.Source") select (n)); return query;; } I then try to populate mya ViewModel in my WebUI layer using the following code var projectedNetworks = from n in GetAllNetworks() select new NetworkViewModel { Name = n.Name, Contacts = from contact in networkList .SelectMany(nc => nc.NetworkContacts) .Where(nc => nc.Member == true) .Where(nc => nc.NetworkId == n.ID) .Select(c => c.Contact) select contact, }; return projectedNetworks; The problem now occurs in my newly createdNetworkViewModel The Contacts object does include any loaded data for RelationshipSource.Target or RelationshipSource.Source The data should is there when run from the original Repository IQueryable object. However the related include data does not seem to get transferred into the new Contacts collection that is created from this IQueryable using the Select New {} code above. Is there a way to preserve this Include data when it gets passed into a new object?

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  • Using Linq2Sql to insert data into multiple tables using an auto incremented primary key

    - by Thomas
    I have a Customer table with a Primary key (int auto increment) and an Address table with a foreign key to the Customer table. I am trying to insert both rows into the database in one nice transaction. using (DatabaseDataContext db = new DatabaseDataContext()) { Customer newCustomer = new Customer() { Email = customer.Email }; Address b = new Address() { CustomerID = newCustomer.CustomerID, Address1 = billingAddress.Address1 }; db.Customers.InsertOnSubmit(newCustomer); db.Addresses.InsertOnSubmit(b); db.SubmitChanges(); } When I run this I was hoping that the Customer and Address table automatically had the correct keys in the database since the context knows this is an auto incremented key and will do two inserts with the right key in both tables. The only way I can get this to work would be to do SubmitChanges() on the Customer object first then create the address and do SubmitChanges() on that as well. This would create two roundtrips to the database and I would like to see if I can do this in one transaction. Is it possible? Thanks

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  • c#: Clean way to fit a collection into a multidimensional array?

    - by Rosarch
    I have an ICollection<MapNode>. Each MapNode has a Position attribute, which is a Point. I want to sort these points first by Y value, then by X value, and put them in a multidimensional array (MapNode[,]). The collection would look something like this: (30, 20) (20, 20) (20, 30) (30, 10) (30, 30) (20, 10) And the final product: (20, 10) (20, 20) (20, 30) (30, 10) (30, 20) (30, 30) Here is the code I have come up with to do it. Is this hideously unreadable? I feel like it's more hacky than it needs to be. private Map createWorldPathNodes() { ICollection<MapNode> points = new HashSet<MapNode>(); Rectangle worldBounds = WorldQueryUtils.WorldBounds(); for (float x = worldBounds.Left; x < worldBounds.Right; x += PATH_NODE_CHUNK_SIZE) { for (float y = worldBounds.Y; y > worldBounds.Height; y -= PATH_NODE_CHUNK_SIZE) { // default is that everywhere is navigable; // a different function is responsible for determining the real value points.Add(new MapNode(true, new Point((int)x, (int)y))); } } int distinctXValues = points.Select(node => node.Position.X).Distinct().Count(); int distinctYValues = points.Select(node => node.Position.Y).Distinct().Count(); IList<MapNode[]> mapNodeRowsToAdd = new List<MapNode[]>(); while (points.Count > 0) // every iteration will take a row out of points { // get all the nodes with the greatest Y value currently in the collection int currentMaxY = points.Select(node => node.Position.Y).Max(); ICollection<MapNode> ythRow = points.Where(node => node.Position.Y == currentMaxY).ToList(); // remove these nodes from the pool we're picking from points = points.Where(node => ! ythRow.Contains(node)).ToList(); // ToList() is just so it is still a collection // put the nodes with max y value in the array, sorting by X value mapNodeRowsToAdd.Add(ythRow.OrderByDescending(node => node.Position.X).ToArray()); } MapNode[,] mapNodes = new MapNode[distinctXValues, distinctYValues]; int xValuesAdded = 0; int yValuesAdded = 0; foreach (MapNode[] mapNodeRow in mapNodeRowsToAdd) { xValuesAdded = 0; foreach (MapNode node in mapNodeRow) { // [y, x] may seem backwards, but mapNodes[y] == the yth row mapNodes[yValuesAdded, xValuesAdded] = node; xValuesAdded++; } yValuesAdded++; } return pathNodes; } The above function seems to work pretty well, but it hasn't been subjected to bulletproof testing yet.

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  • Can I serialize an object if I didn't write the class used to instantiate that object?

    - by Richard77
    Hello, I've a simple class [Serializable] public class MyClass { public String FirstName { get; set: } public String LastName { get; set: } //Bellow is what I would like to do //But, it's not working //I get an exception ContactDataContext db = new ContactDataContext(); public void Save() { Contact contact = new Contact(); contact.FirstName = FirstName; contact.LastName = LastName; db.Contacts.InsertOnSubmit(contact); db.SubmitChanges(); } } I wanted to attach a Save method to the class so that I could call it on each object. When I introduced the above statement which contains ContactDataContext, I got the following error "In assembly ... PublicKeyToken=null' is not marked as serializable" It's clear that the DataContext class is generated by the framework (). I checked and did not see where that class was marked serialize. What can I do to overcome that? What's the rule when I'm not the author of a class? Just go ahead and mark the DataContext class as serializable, and pretend that everything will work? Thanks for helping

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  • LINQtoSQL Custom Constructor off Partial Class?

    - by sah302
    Hi all, I read this question here: http://stackoverflow.com/questions/82409/is-there-a-way-to-override-the-empty-constructor-in-a-class-generated-by-linqtosq Typically my constructor would look like: public User(String username, String password, String email, DateTime birthday, Char gender) { this.Id = Guid.NewGuid(); this.DateCreated = this.DateModified = DateTime.Now; this.Username = username; this.Password = password; this.Email = email; this.Birthday = birthday; this.Gender = gender; } However, as read in that question, you want to use partial method OnCreated() instead to assign values and not overwrite the default constructor. Okay so I got this : partial void OnCreated() { this.Id = Guid.NewGuid(); this.DateCreated = this.DateModified = DateTime.Now; this.Username = username; this.Password = password; this.Email = email; this.Birthday = birthday; this.Gender = gender; } However, this gives me two errors: Partial Methods must be declared private. Partial Methods must have empty method bodies. Alright I change it to Private Sub OnCreated() to remove both of those errors. However I am still stuck with...how can I pass it values as I would with a normal custom constructor? Also I am doing this in VB (converted it since I know most know/prefer C#), so would that have an affect on this?

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  • Read from XML > Add to Listview

    - by Zubirg
    I have some problems getting the data that i read from XML split into seperate columns. Any help this new C# coder would get would be appreciated. XDocument xmlDoc = XDocument.Load("emails.xml"); var t = from c in xmlDoc.Descendants("dt") select (string)c.Element("name") + (string)c.Element("email"); foreach (string item in t) { listView.Items.Add(item); }

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  • ASP.NET MVC- Bizarre problem - suddennly lost all LINQTO SQL data context objects

    - by MikeD
    I was making an edit to a long existing project. Specifically I added some fields to a table and had to delete the table from the LINQTOSQL designer and re-add it. doesn't Also had to do the same for a view. Mode some other code changes and went to build . Now my project won't build because it can't resolve any of the data context objects (all tables and views) in my code. I don't know what I did or how this happeened. I have many tables and views in the project's L2S data context so I don't wont to try and do over. Please any suggestions on how to resolve this problem are greatly appreciated. Desparate! The error messages I am getting are the familiar The type or namespace name 'equipment' could not be found (are you missing a using directive or an assembly reference?)

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