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  • What is the preferred sql server column definition to use for a LINQ to SQL Version property?

    - by Mike Two
    We are using the IsVersion property on the ColumnAttribute on a property in a LINQ to SQL class for optimistic concurrency checks. What should the column definition be in the database? Currently we are using version_number int NOT NULL IDENTITY (1, 1) Do we need Identity? Can we get LINQ to SQL to update the version number for us? The only issue with Identity is that every row has a different number. We'd like to see the number increment by 1 when the row is updated.

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  • How can I evaluate a deferred Linq statement when debugging?

    - by DanO
    I'm debugging in VS2010, and I want to inspect a string value but all I can get the debugger to show me (through watches, hovering, locals, etc.) is: "System.Linq.Enumerable+<TakeIterator>d__3a`1[System.Char]" I don't care if there are side effects from premature evaluation or whatever, I just want to see what the expression would evaluate to if I evaluate it right now at the current breakpoint. How is this done? Also can I change my code in such a way that it evaluates earlier? Not that I care when I'm not debugging... but just wondering. In case it is relevant... (I doubt it.) I'm stuffing a new entity object before saving it to the database... some fields are assigned with LINQ statements, I'm not sure when they get evaluated under the covers of EF. The DB update fails with 'string or binary data would be truncated... So I'm trying to find the too-long field.

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  • Using FileSystemWatcher in detecting a xml file, using Linq in reading the xml file and prompt the results error "Root Element is Missing"

    - by GrayFullBuster
    My application is already working it can detect the xml file and prompt the content of the xml file but sometimes it will prompt "Root element is missing", and sometimes also it is okay but when I open the xml file, it is ok, it has contents on it. How to solve this issue. Here is the screenshot of the error: Here is the code: private void fileSystemWatcher_Created(object sender, System.IO.FileSystemEventArgs e) { string invoice = ""; using (var stream = System.IO.File.Open(e.FullPath, System.IO.FileMode.Open, System.IO.FileAccess.Read, System.IO.FileShare.ReadWrite)) { var doc = System.Xml.Linq.XDocument.Load(stream); var transac = from r in doc.Descendants("Transaction") select new { InvoiceNumber = r.Element("InvoiceNumber").Value, }; foreach (var i in transac) { invoice = i.InvoiceNumber; } } MessageBox.Show(invoice); fileSystemWatcher.EnableRaisingEvents = false; } The error goes here var doc = System.Xml.Linq.XDocument.Load(stream);

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  • Insert objects into a collection with LINQ based on a property of the existing objects in the collection

    - by DavidS
    Hi, I've got a collection of object which contains data as follows: FromTime Duration 2010-12-28 24.0000 2010-12-29 24.0000 2010-12-30 24.0000 2010-12-31 22.0000 2011-01-02 1.9167 2011-01-03 24.0000 2011-01-04 24.0000 2011-01-05 24.0000 2011-01-06 24.0000 2011-01-07 22.0000 2011-01-09 1.9167 2011-01-10 24.0000 In the "FromTime" column, there are data "gaps" i.e. 2011-01-01 and 2011-01-08 are "missing". So what I'd like to do is to loop through a range of dates (in this instance 2010-12-28 to 2011-01-10) and "fill in" the "missing" data with a duration of 0. As I've just started with LINQ, I feel that it should be "fairly" easy but I can't quite get it right. I'm reading the book "LINQ in Action" but feel that I'm still quite a way off before I can resolve this particular issue. So any help would be much appreciated. David

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  • How do i parse the new wow RSS feed? (LINQ to XML)

    - by Sunzaru Sven
    The link i want to parse is here. I'm looking to parse it in "real time" so that as things happen i can send myself messages/tweets and what not. I plan on having each element of the XML from the feed as an item of a class/struct. I'm really looking for LINQ to XML examples, and a good book. I've seen other LINQ to XML articles out there, but i'm just not grasping how they work. Old SQL minds are hard to break perhaps... /shrug.

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  • 'Timeout Expired' error against local SQL Express on only 2 LINQ Methods...

    - by Refracted Paladin
    I am going to sum up my problem first and then offer massive details and what I have already tried. Summary: I have an internal winform app that uses Linq 2 Sql to connect to a local SQL Express database. Each user has there own DB and the DB stay in sync through Merge Replication with a Central DB. All DB's are SQL 2005(sp2or3). We have been using this app for over 5 months now but recently our users are getting a Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. Detailed: The strange part is they get that in two differnt locations(2 differnt LINQ Methods) and only the first time they fire in a given time period(~5mins). One LINQ method is pulling all records that match a FK ID and then Manipulating them to form a Heirarchy View for a TreeView. The second is pulling all records that match a FK ID and dumping them into a DataGridView. The only things I can find in common with the 2 are that the first IS an IEnumerable and the second converts itself from IQueryable - IEnumerable - DataTable... I looked at the query's in Profiler and they 'seemed' normal. They are not very complicated querys. They are only pulling back 10 - 90 records, from one table. Any thoughts, suggestions, hints whatever would be greatly appreciated. I am at my wit's end on this.... public IList<CaseNoteTreeItem> GetTreeViewDataAsList(int personID) { var myContext = MatrixDataContext.Create(); var caseNotesTree = from cn in myContext.tblCaseNotes where cn.PersonID == personID orderby cn.ContactDate descending, cn.InsertDate descending select new CaseNoteTreeItem { CaseNoteID = cn.CaseNoteID, NoteContactDate = Convert.ToDateTime(cn.ContactDate). ToShortDateString(), ParentNoteID = cn.ParentNote, InsertUser = cn.InsertUser, ContactDetailsPreview = cn.ContactDetails.Substring(0, 75) }; return caseNotesTree.ToList<CaseNoteTreeItem>(); } AND THIS ONE public static DataTable GetAllCNotes(int personID) { using (var context = MatrixDataContext.Create()) { var caseNotes = from cn in context.tblCaseNotes where cn.PersonID == personID orderby cn.ContactDate select new { cn.ContactDate, cn.ContactDetails, cn.TimeSpentUnits, cn.IsCaseLog, cn.IsPreEnrollment, cn.PresentAtContact, cn.InsertDate, cn.InsertUser, cn.CaseNoteID, cn.ParentNote }; return caseNotes.ToList().CopyLinqToDataTable(); } }

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  • How can I avoid setting some columns if others haven't changed, when working with Linq To SQL?

    - by Patrick Szalapski
    In LINQ to SQL, I want to avoid setting some columns if others haven't changed? Say I have dim row = (From c in dataContext.Customers Where c.Id = 1234 Select c).Single() row.Name = "Example" ' line 3 dataContext.SubmitChanges() ' line 4 Great, so LINQ to SQL fetches a row, sets the name to "Example" in memory, and generates an update SQL query only when necessary--that is, no SQL will be generated if the customer's name was already "Example". So suppose on line 3, I want to detect if row has changed, and if so, set row.UpdateDate = DateTime.Now. If row has not changed, I don't want to set row.UpdateDate so that no SQL is generated. Is there any good way to do this?

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  • c# How to make linq master detail query for 0..n relationship?

    - by JK
    Given a classic DB structure of Orders has zero or more OrderLines and OrderLine has exactly one Product, how do I write a linq query to express this? The output would be OrderNumber - OrderLine - Product Name Order-1 null null // (this order has no lines) Order-2 1 Red widget I tried this query but is not getting the orders with no lines var model = (from po in Orders from line in po.OrderLines select new { OrderNumber = po.Id, OrderLine = line.LineNumber, ProductName = line.Product.ProductDescription, } ) I think that the 2nd from is limiting the query to only those that have OrderLines, but I dont know another way to express it. LINQ is very non-obvious if you ask me!

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  • How do I "propagate" my VS2008 Data Sources window with a LINQ query table?

    - by Kent S. Clarkson
    I´m (professionally) creating a SQL Server database client by using Visual Studio 2008, C# - Windows Form(s). And I´m using all the built in stuff, provided by my friend VS Studio, dragging and dropping, creating SQL query tables in DataSet.xsd, and so on... I like that. But! I would like to try out LINQ, as I would like to have something that to me is more intuitive than pure SQL... And (here comes the newbie-problem to be solved)! I don´t know where to put the LINQ code to make a table "pop up" in the Data Sources window - meaning I´m completely stuck! How should I do it?

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  • How to choose programaticaly the column to be querried by Linq using PropertyInfo???

    - by Richard77
    Hello, I would like to control how linq querries my database programaticaly. For instance, I'd like to querry the column X, column Y, or column Z, depending on some conditions. First of all, I've created an array of all the properties inside my class called myPropertyInfo. Type MyType = (typeOf(MyClass)); PropertyInfo[] myPropertyInfo = myType.GetProperties( BindingFlags.Public|BindingFlags.Instance); the myPropertyInfo array allows me to access each property details (Name, propertyType, etc) through the index*[i]* Now, how can I use the above information to control how linq querries my DB? Here's a sample of a querry I'd like to exploit. var myVar = from tp in db.MyClass select tp.{expression}; Expression using myPropertyInfo[i] to choose which property(column) to querry. I'm not sure if that's the way of doing it, but if there's another way to do so, I'll be glad to learn. Thanks for helping.

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  • How to choose programaticaly the column to be queried by Linq using PropertyInfo???

    - by Richard77
    Hello, I would like to control how linq querries my database programaticaly. For instance, I'd like to query the column X, column Y, or column Z, depending on some conditions. First of all, I've created an array of all the properties inside my class called myPropertyInfo. Type MyType = (typeOf(MyClass)); PropertyInfo[] myPropertyInfo = myType.GetProperties( BindingFlags.Public|BindingFlags.Instance); The myPropertyInfo array allows me to access each property details (Name, propertyType, etc) through the index*[i]* Now, how can I use the above information to control how linq queries my DB? Here's a sample of a querry I'd like to exploit. var myVar = from tp in db.MyClass select tp.{expression}; Expression using myPropertyInfo[i] to choose which property(column) to query. I'm not sure if that's the way of doing it, but if there's another way to do so, I'll be glad to learn. Thanks for helping.

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  • Linq to SQL DateTime values are local (Kind=Unspecified) - How do I make it UTC?

    - by ericsson007
    Isn't there a (simple) way to tell Linq To SQL classes that a particular DateTime property should be considered as UTC (i.e. having the Kind property of the DateTime type to be Utc by default), or is there a 'clean' workaround? The time zone on my app-server is not the same as the SQL 2005 Server (cannot change any), and none is UTC. When I persist a property of type DateTime to the dB I use the UTC value (so the value in the db column is UTC), but when I read the values back (using Linq To SQL) I get the .Kind property of the DateTime value to be 'Unspecified'. The problem is that when I 'convert' it to UTC it is 4 hours off. This also means that when it is serialized it it ends up on the client side with a 4 hour wrong offset (since it is serialized using the UTC).

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  • How to make a SUM of Dictionary Value nested into a list with LINQ ?

    - by user551108
    Hi All, I have a product object declared as : Product { int ProductID; string ProductName; int ProductTypeID; string ProductTypeName; int UnitsSold Dictionary <string, int> UnitsSoldByYear; } I want to make a sum on UnitsSold and UnitsSoldByYear properties with a Linq query but I didn't know how to make this kind of sum on a dictionary ! Here is my begining linq query code : var ProductTypeSum = from i in ProductsList group i by new { i.ProductTypeID, i.ProductTypeName} into pt select new { ProductTypeID= pt.Key.ProductTypeID, ProductTypeName= pt.Key.ProductTypeName, UnitsSoldSum= pt.Sum(i => i.UnitsSold), // How to make a Dictionary sum here } Thank you for your help !

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  • LINQ to XML

    Gain an understanding of LINQ (Language Integrated Query) to XML and see why you'll never want to use the DOM again.

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  • C# Multiple Property Sort

    - by Ben Griswold
    As you can see in the snippet below, sorting is easy with Linq.  Simply provide your OrderBy criteria and you’re done.  If you want a secondary sort field, add a ThenBy expression to the chain.  Want a third level sort?  Just add ThenBy along with another sort expression. var projects = new List<Project>     {         new Project {Description = "A", ProjectStatusTypeId = 1},         new Project {Description = "B", ProjectStatusTypeId = 3},         new Project {Description = "C", ProjectStatusTypeId = 3},         new Project {Description = "C", ProjectStatusTypeId = 2},         new Project {Description = "E", ProjectStatusTypeId = 1},         new Project {Description = "A", ProjectStatusTypeId = 2},         new Project {Description = "C", ProjectStatusTypeId = 4},         new Project {Description = "A", ProjectStatusTypeId = 3}     };   projects = projects     .OrderBy(x => x.Description)     .ThenBy(x => x.ProjectStatusTypeId)     .ToList();   foreach (var project in projects) {     Console.Out.WriteLine("{0} {1}", project.Description,         project.ProjectStatusTypeId); } Linq offers a great sort solution most of the time, but what if you want or need to do it the old fashioned way? projects.Sort ((x, y) =>         Comparer<String>.Default             .Compare(x.Description, y.Description) != 0 ?         Comparer<String>.Default             .Compare(x.Description, y.Description) :         Comparer<Int32>.Default             .Compare(x.ProjectStatusTypeId, y.ProjectStatusTypeId));   foreach (var project in projects) {     Console.Out.WriteLine("{0} {1}", project.Description,         project.ProjectStatusTypeId); } It’s not that bad, right? Just for fun, let add some additional logic to our sort.  Let’s say we wanted our secondary sort to be based on the name associated with the ProjectStatusTypeId.  projects.Sort((x, y) =>        Comparer<String>.Default             .Compare(x.Description, y.Description) != 0 ?        Comparer<String>.Default             .Compare(x.Description, y.Description) :        Comparer<String>.Default             .Compare(GetProjectStatusTypeName(x.ProjectStatusTypeId),                 GetProjectStatusTypeName(y.ProjectStatusTypeId)));   foreach (var project in projects) {     Console.Out.WriteLine("{0} {1}", project.Description,         GetProjectStatusTypeName(project.ProjectStatusTypeId)); } The comparer will now consider the result of the GetProjectStatusTypeName and order the list accordingly.  Of course, you can take this same approach with Linq as well.

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  • Regular Expression HTML tags

    - by user134615
    I'd like to know whether it exists a way to put the following HTML tags in a regex. What I want is a regex that can match all the start tags with their corresponding closing tags. E.g., Hello There might be more tags inside. I had thought of something like this: ^<([a-z]+)([^<]+)(?:(.)</\1|\s+/)$/, but it wont work. Sorry if this question doesnt belong to this section. Thank you.

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  • What is the best strategy for transforming unicode strings into filenames?

    - by David Cowden
    I have a bunch (thousands) of resources in an RDF/XML file. I am writing a certain subset of the resources to files -- one file for each, and I'm using the resource's title property as the file name. However, the titles are every day article, website, and blog post titles, so they contain characters unsafe for a URI (the necessary step for constructing a valid file path). I know of the Jersey UriBuilder but I can't quite get it to work for my needs as I detailed in a different question on SO. Some possibilities I have considered are: Since each resource should also have an associated URL, I could try to use the name of the file on the server. The down side of this is sometimes people don't name their content logically and I think the title of an article better reflects the content that will be in each text file. Construct a white list of valid characters and parse the string myself defining substitutions for unsafe characters. The downside of this is the result could be just as unreadable as the former solution because presumably the content creators went through a similar process when placing the files on their server. Choose a more generic naming scheme, place the title in the text file along with the other attributes, and tell my boss to live with it. So my question here is, what methods work well for dealing with a scenario where you need to construct file names out of strings with potentially unsafe characters? Is there a solution that better fills out my constraints?

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  • Regex syntax question - trying to understand

    - by Asaf Chertkoff
    i don't know if this question belong here or no, but it is worth a shot. i'm a self taught php programmer and i'm only now starting to grasp the regex stuff. i'm pretty aware of its capabilities when it is done right, but this is something i need to dive in too. so maybe someone can help me, and save me so hours of experiment. i have this string: here is the <a href="http://www.google.com" class="ttt" title="here"><img src="http://www.somewhere.com/1.png" alt="some' /></a> and there is <a href="#not">not</a> a chance... now, i need to perg_match this string and search for the a href tag that has an image in it, and replace it with the same tag with a small difference: after the title attribute inside the tag, i'll want to add a rel="here" attribute. of course, it should ignore links (a href's) that doesn't have img tag inside. help will be appreciated, thanks.

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  • Modifying Service URLs with LINQ to Twitter

    - by Joe Mayo
    It’s funny that two posts so close together speak about flexibility with the LINQ to Twitter provider.  There are certain things you know from experience on when to make software more flexible and when to save time.  This is another one of those times when I got lucky and made the right choice up front. I’m talking about the ability to switch URLs. It only makes sense that Twitter should begin versioning their API as it matures.  In fact, most of the entire API has moved to the v1 URL at “https://api.twitter.com/1/”, except for search and trends.  Recently, Twitter introduced the available and local trends, but hung them off the new v1, and left the rest of the trends API on the old URL. To implement this, I muscled my way into the expression tree during CreateRequestProcessor to figure out which trend I was dealing with; perhaps not elegant, but the code is in the right place and that’s what factories are for.  Anyway, the point is that I wouldn’t have to do this kind of stuff (as much fun as it is), if Twitter would have more consistency. Having went to Chirp last week and seeing the evolution of the API, it looks like my wish is coming true.  …now if they would just get their stuff together on the mess they made with geo-location and places… but again, that’s all transparent if your using LINQ to Twitter because I pulled all of that together in a consistent way so that you don’t have to. Normally, when Twitter makes a change, code breaks and I have to scramble to get the fixes in-place.  This time, in the case of a URL change, the adjustment is easy and no-one has to wait for me.  Essentially, all you need to do is change the URL passed to the TwitterContext constructor.  Here’s an example of instantiating a TwitterContext now: using (var twitterCtx = new TwitterContext(auth, "https://api.twitter.com/1/", "https://search.twitter.com/")) The third parameter constructor is the SearchUrl, which is used for Search and Trend APIs. You probably know what’s coming next; another constructor, but with the SearchUrl parameter set to the new URL as follows: using (var twitterCtx = new TwitterContext(auth, "https://api.twitter.com/1/", "https://api.twitter.com/1/")) One consequence of setting the URL this way is that you set the URL for both Trends and Search.  Since Search is still using the old URL, this is going to break for Search queries. You could always instantiate a special TwitterContext instance for Search queries, with the old URL set. Alternatively, you can use the TwitterContext’s SearchUrl property. Here’s an example: twitterCtx.SearchUrl = "https://api.twitter.com/1/"; var trends = (from trend in twitterCtx.Trends where trend.Type == TrendType.Daily && trend.Date == DateTime.Now.AddDays(-2).Date select trend) .ToList(); Notice how I set the SearchUrl property just-in-time for the query. This allows you to target the URL for each specific query. Whichever way you prefer to configure the URL, it’s your choice. So, now you know how to set the URL to be used for Trend queries and how to prevent whacking your Search queries. I’ll be updating the Trend API to use same URL as all other APIs soon, so the only API left to use the SearchUrl will be Search, but for the short term, it’s Trends and Search. Until I make this change, you’ll have a viable work-around by setting the URL yourself, as explained above. These were the Search and Trend URLs, but you might be curious about the second parameter of the TwitterContext constructor; that’s the URL for all other APIs (the BaseUrl), except for Trend and Search. Similarly, you can use the TwitterContext’s BaseUrl property to set the BaseUrl. Setting the BaseUrl can be useful when communicating with other services. In addition to Twitter changing URLs, the Twitter API has been adopted by other companies, such as Identi.ca, Tumblr, and  WordPress.  This capability lets you use LINQ to Twitter with any of these services.  This is a testament to the success of the Twitter API and it’s popularity. No doubt we’ll have hills and valleys to traverse as the Twitter API matures, but hopefully there will be enough flexibility in LINQ to Twitter to make these changes as transparent as possible for you. @JoeMayo

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  • How I use RegExp in my Java program? [migrated]

    - by MIH1406
    I have the following string examples: 00001 1 12 123 00002 3 7 321 00003 99 23 332 00004 192 50 912 In a separate text file. Numbers are separated by tabs not spaces. I tried to read the file and print each line if it matches a given RegExp, but I could not find the suitable RegExp for these lines. private static void readFile() { String fileName = "processes.lst"; FileReader file = null; String result = ""; try { file = new FileReader(fileName); BufferedReader reader = new BufferedReader(file); String line = null; String regEx = "[0-9]\t[0-9]\t[0-9]\t[0-9]"; while((line = reader.readLine()) != null) { if(line.matches(regEx)) { result += "\n" + line; } } } catch(Exception e) { System.out.println(e.getMessage()); } finally { if(file != null) try { file.close(); } catch(Exception e) { System.out.println(e.getMessage()); } } System.out.println(result); } I ended up without any string being printed!!

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  • String patterns that can be used to filter and group files

    - by Louis Rhys
    One of our application filters files in certain directory, extract some data from it and export a document from the extracted data. The algorithm for extracting the data depends on the file, and so far we use regex to select the algorithm to be used, for example .*\.txt will be processed by algorithm A, foo[0-5]\.xml will be processed by algo B, etc. However now we need some files to be processed together. For example, in one case we need two files, foo.*\.xml and bar.*\.xml. Part of the information to be extracted exist in the foo file, and the other part in the bar file. Moreover, we need to make sure the wild card is compatible. For example, if there are 6 files foo1.xml foo23.xml bar1.xml bar9.xml bar23.xml foo4.xml I would expect foo1 and bar1 to be identified as a group, and foo23 and bar23 as another group. bar9 and foo4 has no pair, so they will not be treated. Now, since the filter is configured by user, we need to have a pattern that can express the above requirement. I don't think you can express meaning like above in standard regex. (foo|bar).*\.xml will match all 6 file above and we can't identify which file is paired for a particular file. Is there any standard pattern that can express it? Or any idea how to modify regex to support this, that can be implemented easily?

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