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  • Storing records in a dropdownlist from DB without using LINQ Data source

    - by user1318369
    I have a website for dance academy where Users can register and add/drop dance classes. In the web page to drop a particular dance, for a particular user, the dropdown displays her registered dances. Now I want to delete one of the dances from the list. So i'll remove the row from the table and also from the dropdownlist. The problem is that everytime the item with the lowest ID (index) is getting deleted, no matter which one the user selects. I think I am storing the DataTextField and DataValueField for the dropdown incorrectly. Can someone please help me out? The code is: private void PopulateDanceDropDown() { var registereddanceList = from dd in context.DANCER_AND_DANCE where dd.UserId == dancerId select new { Text = dd.DanceName, Value = dd.DanceId }; dances.DataSource = registereddanceList; dances.DataTextField = "Text"; dances.DataValueField = "Value"; dances.DataBind(); } protected void dropthedance(object o, EventArgs e) { String strDataValueField = dances.SelectedItem.Value; int danceIDFromDropDown = Convert.ToInt32(strDataValueField); var dancer_dance = from dd in context.DANCER_AND_DANCE where dd.DanceId == danceIDFromDropDown select dd; foreach (var dndd in dancer_dance) { context.DANCER_AND_DANCE.DeleteOnSubmit(dndd); } try { context.SubmitChanges(); } catch (Exception ex) { Console.WriteLine(ex); } PopulateDanceDropDown(); }

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  • VB.NET and linQ: How to delete entries from a dictionary using the value

    - by user350233
    I have a dictionary collection as bleow: mydic.addvalue(key1, val1) mydic.addvalue(key2, val1) mydic.addvalue(key3, val1) mydic.addvalue(key4, val2) mydic.addvalue(key5, val2) From the above dictionary I want to delete all the entries where value == "val1", so that the result would have only following entry: mydic.addvalue(key4, val2) mydic.addvalue(key5, val2) My VB source code is on VS2008 and targeted for 3.5

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  • How to use the IN operator in linq

    - by Hallaghan
    I'm querying a view and filtering the results with a column named status. I'd like to query it so I can search for rows with different status, by using the IN operator as I'd do in SQL. As so: SELECT * FROM VIEW WHERE Status in ('....', '.....') How can I achieve this?

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  • Linq-to-sql join/where?

    - by Curtis White
    I've the following table structures Users id Types id isBool UsersTypes userid types I want to select all the UserTypes based on id and isBool. I tried this query var q = from usertype in usertypes from type in types where type.isBool == false where userstypes.user == id select usertype; But this did not work as expected. My questions are: Why? Is there any difference in using the join on syntax vs where, where vs where cond1 && cond2? My understanding is query optimizer will optimize. Is there any difference in using where cond1 == var1 && cond2 == var2 with and without the parenthesis? This seems peculiar that it is possible to build this without parenthesis What type of query do I need in this case? I can see that I could do a subquery or use a group but not 100% sure if it is required. An example might be helpful. I'm thinking a subquery may be required in this case.

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  • Making linq avoid using in memory filtering where possible

    - by linqmonkey
    Consider the these two LINQ2SQL data retrieval methods. The first creates a 'proper' SQL statement that filters the data, but requires passing the data context into the method. The second has a nicer syntax but loads the entire list of that accounts projects, then does in memory filtering. Is there any way to preserve the syntax of the second method but with the performance advantage of the first? public partial class Account { public IQueryable<Project> GetProjectsByYear(LinqDataContext context, int year) { return context.Projects.Where(p => p.AccountID==this.AccountID && p.Year==year).OrderBy(p => p.ProjectNo) } public IQueryable<Project> GetProjectsByYear(int year) { return this.Projects.Where(p => p.Year==year).OrderBy(p => p.ProjectNo).AsQueryable() } }

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  • linq to sql update data

    - by pranay
    can i update my employee record as given in below function or i have to make query of employee collection first and than i update data public int updateEmployee(App3_EMPLOYEE employee) { DBContextDataContext db = new DBContextDataContext(); db.App3_EMPLOYEEs.Attach(employee); db.SubmitChanges(); return employee.PKEY; } or i have to do this public int updateEmployee(App3_EMPLOYEE employee) { DBContextDataContext db = new DBContextDataContext(); App3_EMPLOYEE emp = db.App3_EMPLOYEEs.Single(e => e.PKEY == employee.PKEY); db.App3_EMPLOYEEs.Attach(employee,emp); db.SubmitChanges(); return employee.PKEY; } But i dont want to use second option is there any efficient way to update data

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  • Query decendants in XML to Linq

    - by Gordon
    I have the following xml data: <portfolio> <item> <title>Site</title> <description>Site.com is a </description> <url>http://www.site.com</url> <photos> <photo url="http://www.site.com/site/thumbnail.png" thumbnail="true" description="Main" /> <photo url="http://www.site.com/site/1.png" thumbnail="false" description="Main" /> </photos> </item> </portfolio> In c# I am using the following link query: List list = new List(); XDocument xmlDoc = XDocument.Load(HttpContext.Current.Server.MapPath("~/app_data/portfolio.xml")); list = (from portfolio in xmlDoc.Descendants("item") select new PortfolioItem() { Title = portfolio.Element("title").Value, Description = portfolio.Element("description").Value, Url = portfolio.Element("url").Value }).ToList(); How do I go about querying the photos node? In the PortfolioItem class I have a property: List Photos {get;set;} Any ideas would be greatly appreciated!

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  • Grabbing Just The Top Entry From A LINQ Query

    - by Soo
    I basically have a lot of poorly designed code to do something that, I'm sure, can be done far more elegantly. What I'm trying to do is grab the last date from a database table. var Result = from a in DB.Table orderby a.Date descending select new {Date = a}; foreach(var Row in Result) { LastDate = Row.Date.Date; break; } Basically, there's a foreach loop that is designed to run only once. Crappy code! What's a "best practice" way to accomplish the same thing?

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  • Exploding a range of dates with LINQ

    - by Robert Gowland
    If I have a pair of dates, and I want to generate a list of all the dates between them (inclusive), I can do something like: System.DateTime s = new System.DateTime(2010, 06, 05); System.DateTime e = new System.DateTime(2010, 06, 09); var list = Enumerable.Range(0, (e - s).Days) .Select(value => s.AddDays(value)); What I'm stuck on is that I've got a list of pairs of dates that I want to explode into a list of all the dates between them. Example: {2010-05-06, 2010-05-09}, {2010-05-12, 2010-05-15} should result in {2010-05-06, 2010-05-07, 2010-05-08, 2010-05-09, 2010-05-12, 2010-05-13, 2010-05-14, 2010-05-15} Note the pairs of dates are guaranteed not to overlap each other.

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  • C# LINQ join With Just One Row

    - by Soo
    I'm trying to make a query that grabs a single row from an SQL database and updates it. TableA AId AValue TableB BId AId BValue Ok, so TableA and TableB are linked by AId. I want to select a row in TableB based on AValue using a join. The following query is what I have and only grabs a value from TableB based on AId, I just don't know how to grab a row from TableB using AValue. I know you would need to use a join, but I'm not sure how to accomplish that. var row = DbObject.TableB.Single(x => x.AId == 1) row.BValue = 1; DbObject.SubmitChanges();

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  • LINQ Expression help with Func TEntity,TType

    - by Chris Conway
    I have a repository method that accepts an order by parameter in the form: public IEnumerable<TEntity> Get<TEntity>(Expression<Func<TEntity,string>> orderBy) Now that works fine when trying to sort by a property of type string, var entities = rep.Get(x => x.Name); but what if i want to sort by double or int or any other type. Doing something like var entities = rep.Get(x => x.Price); obviously throws a compile error saying I can't convert double to string. How can I make this more generic so I can sort by any property in my entity, or at least the properties where the type implements IComparable or something similar?

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  • Linq Return node level of hierarchical xml

    - by Ryan
    In a treeview you can retrieve the level of an item. I am trying to accomplish the same thing with the given input being an object. The XML data I will use for this example would be something like the following <?xml version="1.0" encoding="utf-8" ?> <Testing> <Numbers> <Number val="1"> <Number val="1.1"> <Number val="1.1.1"> <Number val="1.1.2" /> <Number val="1.1.3" /> <Number val="1.1.4" /> </Number> </Number> <Number val="1.2" /> <Number val="1.3" /> <Number val="1.4" /> </Number> <Number val="2" /> <Number val="3" /> <Number val="4" /> </Numbers> <Numbers> <Number val="5" /> <Number val="6" /> <Number val="7" /> <Number val="8" /> </Numbers> </Testing> This one is kicking my butt!

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  • SQL and/or LINQ query for determining daily increases in viewers

    - by Gio
    We're montioring usage of a certain resources by monitoring users logins (We can see user logins growing daily). After filtering out repeat inter day logins for users, we'd like to track the # of users using the service each day, and then using that info to determine overall incremental gains for each calendar day. Our table is pretty simple: class ServiceLogin { String login; DateTime loginTime; }

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  • Using Linq to filter parents by their children

    - by Nick L
    Having some problems with my Silverlight app (with RIA services) filtering my results. The idea is on the client I set up the EntityQuery and its filters and call load. However this isn't working for me. Heres my code. public void FireQuery(string filterValue) { EntityQuery<Parent> query = m_ParentDomainContext.GetParentQuery(); query = query.Where(p => p.Children.Any(c => c.Name.Contains(filterValue))); m_ParentDomainContext.Load(query, Query_Completed, null); } Compiles just fine, however, runtime I get "Query operator 'Any' is not supported." Exception. Does anyone know of a good way to filter like this? Again, I'm looking for a way to set this up on the client.

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  • LINQ Query to filter DTO

    - by brabone
    I have an array...and I need to exclude all the items in this array of string from the masterList.customField as shown below string[] excludeItem = {"a","b","c"}; CustomDTO[] masterList = service.LoadMasterList(); masterList.Where(c=> masterList.customField NOT IN excludeItem How do I achieve the NOT IN part above?

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  • 'Random' Orderby in webservice using LINQ To Entities

    - by MrDean
    Morning all Now I know there is a reason to this odering but my tiny little brain can't get my head around it. I am using a webservice to pull through data to a webp[age and have the following that is so far pulling data through from UUF1: public string[] GetBuyer(string Memberkey) { try { WebService.EntitiesConnection buyer = new WebService.EntitiesConnection(); return buyer.tblProducts .Where(p => p.MemberId == Memberkey) .OrderBy(p => p.UnitUserfield1) .Select(p => p.UnitUserfield1) .Distinct() .ToArray(); } catch (Exception) { return null; } } This works fine and pulls the data through but in a strange order. Where I would expect results of A B C D E F, it appears to be returning A C E B D F. Could someone point out the error in my ways please?

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  • Linq.Where-to-SQL on a text field comparing to a list of values

    - by StampedeXV
    Customer.text is a field in an T-SQL DB (that I do not control and thus may not alter) of type "text". I'd like to do something like this: List<string> compare = new List<string>(); compare.Add("one"); compare.Add("two"); var q = from t in customer where t.text.Contains( compare.First()) select t; this will work. But now I'd like to do something like: (!NOT WORKING!) var q = from t in customer where compare.Contains( t.text ) select t; How can I achieve this? Is it even possible?

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  • How do I switch the table that is queried with linq-to-sql

    - by Ian Ringrose
    We have two tables with the same set of columns; depending on the “type” of object the value is stored in one of the two tables. I wish to use common code to access these two tables. If I was using “raw sql” I could just use String.Format() to change the table name. (Likewise for updates etc) The two separate tables are needed as the data access patterns are very different for the common queries on the two tables and therefore different indexes are needed. “Views” and “instead of triggers” etc to make the tables look like a single table are not liked here. A lot of our customers use low end version of SqlServer so we cannot use partition tables.

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  • LINQ to Entites: Doing a count over one-to-many relationships

    - by chris
    I have a couple of tables where there are one to many relationships. Let's say I have a Country table, a State table with a FK to Country, and a City table with a FK to State. I'd like to be able to create a count of all Cities for a given country, and also a count of cities based on a filter - something like: foreach( var country in Model.Country ) { total = country.State.All().City.All().Count() ; filtered = country.State.All().City.Any(c=>c.field == value).Count(); } Obviously, this doesn't work - is there any way to do this?

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  • Objects in Java ArrayList don't get updated.

    - by Sbm007
    This is going to be a very long post, hopefully you can understand what I'm talking about and I appreciate any help. Thanks Basically, I've created a personal, non-commercial project (which I don't plan to release) that can read ZIP and RAR files. It can only read the contents in the archive, the folders inside, the files inside the folders and its properties (such as last modified date, last modified time, CRC checksum, uncompressed size, compressed size and file name). It can't extract files either, so it's really a ZIP/RAR viewer if you may. Anyway that's slightly irrelevant to my problem but I thought I'd give you some background info. Now for my problem: I can successfully list all the folders and files inside a ZIP archive, so now I want to take that raw input and link it together in some useful way. I made 2 classes: ArchiveFile (represents a file inside a ZIP) and ArchiveFolder (represents a folder inside a ZIP). They both have some useful methods such as getLastModifiedDate, getName, getPath and so on. But the difference is that ArchiveFolder can hold an ArrayList of ArchiveFile's and additional ArchiveFolder's (think of this as files and folders inside a folder). Now I want to populate my raw input into one root ArchiveFolder, which will have all the files in the root dir of the ZIP in the ArchiveFile's ArrayList and any additional folders in the root dir of the ZIP in the ArchiveFolder's ArrayList (and this process can continue on like this like a chain reaction (more files/folders in that ArchiveFolder etc etc). So I came up with the following code: while (archive.hasMore()) { String path = ""; ArchiveFolder current = root; String[] contents = archive.getName().split("/"); for (int x = 0; x < contents.length; ++x) { if (x == (contents.length - 1) && !archive.getName().endsWith("/")) { // If on last item and item is a file path += contents[x]; // Update final path ArchiveFile file = new ArchiveFile(path, contents[x], archive.getUncompressedSize(), archive.getCompressedSize(), archive.getModifiedTime(), archive.getModifiedDate(), archive.getCRC()); current.addFile(file); // Create and add the file to the current ArchiveFolder } else if (x == (contents.length - 1)) { // Else if we are on last item and it is a folder path += contents[x] + "/"; // Update final path ArchiveFolder folder = new ArchiveFolder(path, contents[x], archive.getModifiedTime(), archive.getModifiedDate()); current.addFolder(folder); // Create and add this folder to the current ArchiveFile } else { // Else if we are still traversing through the path path += contents[x] + "/"; // Update path ArchiveFolder folder = new ArchiveFolder(path, contents[x]); current.addFolder(folder); // Create and add folder (remember we do not know the modified date/time as all we know is the path, so we can deduce the name only) current = folder; // Update current ArchiveFolder to the newly created one for the next iteration of the for loop } } archive.getNext(); } Assume that root is the root ArchiveFolder (initially empty). And that archive.getName() returns the name of the current file OR folder in the following fashion: file.txt or folder1/file2.txt or folder4/folder2/ (this is a empty folder) etc. So basically the relative path from the root of the ZIP archive. Please read through the comments in the above code to familiarize yourself with it. Also assume that the addFolder method in an ArchiveFile, only adds the folder if it doesn't exist already (so there are no multiple folders) and it also updates the time and date of an existing folder if it is blank (ie it was a intermediate folder we only knew the name of, but now we know its details). The code for addFolder is (pretty self-explanitory): public void addFolder(ArchiveFolder folder) { int loc = folders.indexOf(folder); // folders is the ArrayList containing ArchiveFolder's if (loc == -1) { folders.add(folder); } else { ArchiveFolder real = folders.get(loc); if (real.time == null) { real.setTime(folder.getTime()); real.setDate(folder.getDate()); } } } So I can't see anything wrong with the code, it works and after finishing, the root ArchiveFolder contains all the files in the root of the ZIP as I want it to, and it contains all the direcories in the root folder as I want it to. So you'd think it works as expected, but no the ArchiveFolder's in the root folder don't contain the data inside those 'child' folders, it's just a blank folder with no additional files and folders (while it does really contain some more files/folders when viewed in WinZip). After debugging using Eclipse, the for loop does iterate through all the files (even those not included above), so this led me to believe that there is a problem with this line of the code: current = folder; What it does is, it updates the current folder (used as an intermediate by the loop) to the newly added folder. I thought Java passed by reference and thus all new operations and new additions in future ArchiveFile's and ArchiveFolder's are automatically updated, and parent ArchiveFolder's will be updated accordingly. But that does not appear to be the case? I know this is a long ass post and I really hope anyone can help me out with this. Thanks in advance.

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  • LINQ query to navigate an object hierachy

    - by TesterTurnedDeveloper
    Let's say I have an object graph of Countries / States / Cities, like below: public class City { public string Name { get; set; } } public class State { public List<City> Cities { get; set; } } public class Country { public List<State> States { get; set; } } Is there a simple way to query a List<Country> to get all the cities?

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  • Using LINQ, need help splitting a byte array on data received from Silverlight sockets

    - by gcadmes
    The message packats received contains multiple messages deliniated by a header=0xFD and a footer=0xFE // sample message packet with three // different size messages List<byte> receiveBuffer = new List<byte>(); receiveBuffer.AddRange(new byte[] { 0xFD, 1, 2, 0xFE, 0xFD, 1, 2, 3, 4, 5, 6, 7, 8, 0xFE, 0xFD, 33, 65, 25, 44, 0xFE}); // note: this sample code is without synchronization, // statements, error handling...etc. while (receiveBuffer.Count > 0) { var bytesInRange = receiveBuffer.TakeWhile(n => n != 0xFE); foreach (var n in bytesInRange) Console.WriteLine(n); // process message.. // 1) remove bytes read from receive buffer // 2) construct message object... // 3) etc... receiveBuffer.RemoveRange(0, bytesInRange.Count()); } As you can see, (including header/footer) the first message in this message packet contains 4 bytes, and the 2nd message contains 10 bytes,a and the 3rd message contains 6 bytes. In the while loop, I was expecting the TakeWhile to add the bytes that did not equal the footer part of the message. Note: Since I am removing the bytes after reading them, the header can always be expected to be at position '0'. I searched examples for splitting byte arrays, but non demonstrated splitting on arrays of unknown and fluctuating sizes. Any help will be greatly appreciated. thanks much!

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  • Linq to Sql GroupJoin Paging oddity

    - by OllyA
    I have noticed a strange Sql Translation in a LinqToSql Query I was trying to optimise. If I execute the following Recipients.GroupJoin( RecipientAttributes, x => x.Recipient_Id, y => y.Recipient_Id, (x,y) => new {Recipient = x, Attributes = y}) .Skip(1) .Take(1000) It executes in a single query as expected. However Recipients.GroupJoin( RecipientAttributes, x => x.Recipient_Id, y => y.Recipient_Id, (x,y) => new {Recipient = x, Attributes = y}) .Skip(0) .Take(1000) executes in a separate query for each Attributes selection. Removing the Skip(0) makes no difference either. Can anyone explain this and is there something I can do to get the first page query executing in a single sql statement?

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  • GetByLatest in LINQ ?

    - by Ritz
    hello all, Please provide me a solution for GetByLatest it is giving me an error How to use this "GetByLatest" IList<IRss> news = new Trytable().GetByLatest().Cast<IRss>().ToList(); please help me Thanks Ritz

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