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  • XDocument + IEnumerable is causing out of memory exception in System.Xml.Linq.dll

    - by Manatherin
    Basically I have a program which, when it starts loads a list of files (as FileInfo) and for each file in the list it loads a XML document (as XDocument). The program then reads data out of it into a container class (storing as IEnumerables), at which point the XDocument goes out of scope. The program then exports the data from the container class to a database. After the export the container class goes out of scope, however, the garbage collector isn't clearing up the container class which, because its storing as IEnumerable, seems to lead to the XDocument staying in memory (Not sure if this is the reason but the task manager is showing the memory from the XDocument isn't being freed). As the program is looping through multiple files eventually the program is throwing a out of memory exception. To mitigate this ive ended up using System.GC.Collect(); to force the garbage collector to run after the container goes out of scope. this is working but my questions are: Is this the right thing to do? (Forcing the garbage collector to run seems a bit odd) Is there a better way to make sure the XDocument memory is being disposed? Could there be a different reason, other than the IEnumerable, that the document memory isnt being freed? Thanks. Edit: Code Samples: Container Class: public IEnumerable<CustomClassOne> CustomClassOne { get; set; } public IEnumerable<CustomClassTwo> CustomClassTwo { get; set; } public IEnumerable<CustomClassThree> CustomClassThree { get; set; } ... public IEnumerable<CustomClassNine> CustomClassNine { get; set; }</code></pre> Custom Class: public long VariableOne { get; set; } public int VariableTwo { get; set; } public DateTime VariableThree { get; set; } ... Anyway that's the basic structures really. The Custom Classes are populated through the container class from the XML document. The filled structures themselves use very little memory. A container class is filled from one XML document, goes out of scope, the next document is then loaded e.g. public static void ExportAll(IEnumerable<FileInfo> files) { foreach (FileInfo file in files) { ExportFile(file); //Temporary to clear memory System.GC.Collect(); } } private static void ExportFile(FileInfo file) { ContainerClass containerClass = Reader.ReadXMLDocument(file); ExportContainerClass(containerClass); //Export simply dumps the data from the container class into a database //Container Class (and any passed container classes) goes out of scope at end of export } public static ContainerClass ReadXMLDocument(FileInfo fileToRead) { XDocument document = GetXDocument(fileToRead); var containerClass = new ContainerClass(); //ForEach customClass in containerClass //Read all data for customClass from XDocument return containerClass; } Forgot to mention this bit (not sure if its relevent), the files can be compressed as .gz so I have the GetXDocument() method to load it private static XDocument GetXDocument(FileInfo fileToRead) { XDocument document; using (FileStream fileStream = new FileStream(fileToRead.FullName, FileMode.Open, FileAccess.Read, FileShare.Read)) { if (String.Compare(fileToRead.Extension, ".gz", true) == 0) { using (GZipStream zipStream = new GZipStream(fileStream, CompressionMode.Decompress)) { document = XDocument.Load(zipStream); } } else { document = XDocument.Load(fileStream); } return document; } } Hope this is enough information. Thanks Edit: The System.GC.Collect() is not working 100% of the time, sometimes the program seems to retain the XDocument, anyone have any idea why this might be?

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  • Copy Rows in a One to Many with LINQ (2 SQL)

    - by Refracted Paladin
    I have a table that stores a bunch of diagnosis for a single plan. When the users create a new plan I need to copy over all existing diagnosis's as well. I had thought to try the below but this is obviously not correct. I am guessing that I will need to loop through my oldDiagnosis part, but how? Thanks! My Attempt so far... public static void CopyPlanDiagnosis(int newPlanID, int oldPlanID) { using (var context = McpDataContext.Create()) { var oldDiagnosis = from planDiagnosi in context.tblPlanDiagnosis where planDiagnosi.PlanID == oldPlanID select planDiagnosi; var newDiagnosis = new tblPlanDiagnosi { PlanID = newPlanID, DiagnosisCueID = oldDiagnosis.DiagnosisCueID, DiagnosisOther = oldDiagnosis.DiagnosisOther, AdditionalInfo = oldDiagnosis.AdditionalInfo, rowguid = Guid.NewGuid() }; context.tblPlanDiagnosis.InsertOnSubmit(newDiagnosis); context.SubmitChanges(); } }

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  • How to retrieve indentity column vaule after insert using LINQ

    - by Hobey
    Could any of you please show me how to complete the following tasks? // Prepare object to be saved // Note that MasterTable has MasterTableId as a Primary Key and it is an indentity column MasterTable masterTable = new MasterTable(); masterTable.Column1 = "Column 1 Value"; masterTable.Column2 = 111; // Instantiate DataContext DataContext myDataContext = new DataContext("<<ConnectionStrin>>"); // Save the record myDataContext.MasterTables.InsertOnSubmit(masterTable); myDataContext.SubmitChanges(); // ?QUESTION? // Now I need to retrieve the value of MasterTableId for the record just inserted above. Kind Regards

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  • LINQ to XML: suppressing redundant namespace attribute in child nodes

    - by GSerg
    If a node belongs to a namespace, it's children by default belong to the same namespace. So there's no need to provide an xmlns attribute on each child, which is good. However. If I create two nodes like this: Dim parent = <parent xmlns="http://my.namespace.org"/> Dim child = <child xmlns="http://my.namespace.org">value</child> parent.Add(child) Console.WriteLine(parent.ToString) The result is this: <parent xmlns="http://my.namespace.org"> <child xmlns="http://my.namespace.org">value</child> </parent> But, if create them in a less convenient way: Dim parent = <parent xmlns="http://my.namespace.org"/> Dim child As New XElement(XName.Get("child", "http://my.namespace.org")) With {.Value = "value"} parent.Add(child) Console.WriteLine(parent.ToString) The result is more desirable: <parent xmlns="http://my.namespace.org"> <child>value</child> </parent> Obviously, I'd prefer to use the first way because it is so much more intuitive and easy to code. There's also another reason to not use method 2 -- sometimes I need to create nodes with XElement.Parse, parsing a string that contains an xmlns attribute, which produces exactly same results as method 1. So the question is -- how do I get the pretty output of method 2, creating nodes as in method 1? The only option I see is to create a method that would clone given XElement, effectively recreating it according to method 2 pattern, but that seems ugly. I'm looking for a more obvious solution I overlooked for some reason.

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  • Copy Rows in a One to Many with LINQ to SQL

    - by Refracted Paladin
    I have a table that stores a bunch of diagnosis for a single plan. When the users create a new plan I need to copy over all existing diagnosis's as well. I had thought to try the below but this is obviously not correct. I am guessing that I will need to loop through my oldDiagnosis part, but how? Thanks! My Attempt so far... public static void CopyPlanDiagnosis(int newPlanID, int oldPlanID) { using (var context = McpDataContext.Create()) { var oldDiagnosis = from planDiagnosi in context.tblPlanDiagnosis where planDiagnosi.PlanID == oldPlanID select planDiagnosi; var newDiagnosis = new tblPlanDiagnosi { PlanID = newPlanID, DiagnosisCueID = oldDiagnosis.DiagnosisCueID, DiagnosisOther = oldDiagnosis.DiagnosisOther, AdditionalInfo = oldDiagnosis.AdditionalInfo, rowguid = Guid.NewGuid() }; context.tblPlanDiagnosis.InsertOnSubmit(newDiagnosis); context.SubmitChanges(); } }

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  • LINQ and the use of Repeat and Range operator

    - by vik20000in
    LINQ is also very useful when it comes to generation of range or repetition of data.  We can generate a range of data with the help of the range method.     var numbers =         from n in Enumerable.Range(100, 50)         select new {Number = n, OddEven = n % 2 == 1 ? "odd" : "even"}; The above query will generate 50 records where the record will start from 100 till 149. The query also determines if the number is odd or even. But if we want to generate the same number for multiple times then we can use the Repeat method.     var numbers = Enumerable.Repeat(7, 10); The above query will produce a list with 10 items having the value 7. Vikram

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  • Sort method versus OrderBy LINQ extension method

    - by nmarun
    I have a class Product with an Id and a Name as properties. There are multiple ways of getting a list of products to display in sorted/ordered fashion, say, by the Name of the product. The two I’m concerned about here are the Sort and the OrderBy extension method through LINQ and the difference between them. 1: public class Product 2: { 3: public int Id { get; set; } 4: public string Name { get; set; } 5: } Below is the list of products that I’ll be using and is defined somewhere in the Program.cs...(read more)

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  • LINQ/LAMBDA filter query by date [on hold]

    - by inquisitive_one
    I'm trying to use LINQ to SQL to retrieve earnings data for a particular date range. Currently the table is set up as follows: Comp Eps Year Quarter IBM .5 2012 2 IBM .65 2012 3 IBM .60 2012 4 IBM .5 2011 2 IBM .7 2013 1 IBM .8 2013 2 Except for Eps, all fields have a data type of string or char. Eps has a data type of double. Here's my code: var myData = myTable .Where(t => t.Comp.Equals("IBM") && Convert.Int32(string.Format("{0}{1}", t.Year, t.Quarter)) <= 20131); I get the following error when I tried that code: Method 'System.String Format(System.String, System.Object, System.Object)' has no supported translation to SQL How can I select all Eps that has a year & quarter less than "20132" using a lambda expression?

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  • Using linq to parse file [closed]

    - by Emaan Abdul majeed
    i am working parsing textfile using LINQ but got struc on it,its going outof range exception string[] lines = File.ReadAllLines(input); var t1 = lines .Where(l => !l.StartsWith("#")) .Select(l => l.Split(' ')) .Select(items => String.Format("{0}{1}{2}", items[1].PadRight(32), //items[1].PadRight(16) items[2].PadRight(32), items[3].PadRight(32))); var t2 = t1 .Select(l => l.ToUpper()); foreach (var t in t2) Console.WriteLine(t); and file is about 200 to 500 lines and i want to extract specific information so i need to split that information to different structure so how to do it this..

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  • Is there something like LINQ for Java?

    - by Kb
    Started to learn LINQ with C#. Especially LINQ to Objects and LINQ to XML. I really enjoy the power of LINQ. I learned that there is something called JLINQ a Jscript implementation. Also (as Catbert posted) Scala will have LINQ Do you know if LINQ or something similar will be a part of Java 7? Update: Interesting post from 2008 - http://stackoverflow.com/questions/346721/linq-for-java

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  • Favorite Visual Studio 2010 Extensions, Update

    - by Scott Dorman
    With the release of the Visual Studio Pro Power Tools (and many other new extensions having been released), my list of favorite Visual Studio extensions has changed. All of these extensions are available in the Visual Studio Gallery. Here is the list of extensions that I currently have installed and find useful: Bing Start Page CodeCompare Collapse Selection In Solution Explorer Collapse Solution Color Picker Completion Extension Analyzer Find Results Highlighter Find Results Tweak (Available from CodePlex) Format Document HelpViewerKeywordIndex HighlightMultiWord Image Insertion Indentation Matcher Extension ItalicComments MoveToRegionVSX Numbered Bookmarks PowerCommands for Visual Studio 2010 Regular Expressions Margin Search Work Items for TFS 2010 Source Outliner Spell Checker Structure Adornment This also installs the following extensions: BlockTagger BlockTaggerImpl SettingsStore SettingsStoreImpl StyleCop Team Founder Server Power Tools TFS Auto Shelve Visual Studio Color Theme Editor Visual Studio Pro Power Tools VS10x Code Map VS10x Code Marker VS10x Collapse All Projects VS10x Editor View Enhancer VS10x Insert Debug Names VS10x Selection Popup VS10x Super Copy Paste VSCommands 2010 Word Wrap with Auto-Indent   Technorati Tags: Visual Studio,Extensions

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  • Favorite Visual Studio 2010 Extensions

    - by Scott Dorman
    Now that Visual Studio 2010 has been released, there are a lot of extensions being written. In fact, as of today (May 1, 2010 at 15:40 UTC) there are 809 results for Visual Studio 2010 in the Visual Studio Gallery. If you filter this list to show just the free items, there are still 251 extensions available. Given that number (and it is currently increasing weekly) it can be difficult to find extensions that are useful. Here is the list of extensions that I currently have installed and find useful: Word Wrap with Auto-Indent Indentation Matcher Extension Structure Adornment This also installs the following extensions: BlockTagger BlockTaggerImpl SettingsStore SettingsStoreImpl Source Outliner Triple Click ItalicComments Go To Definition Spell Checker Remove and Sort Using Format Document Open Folder in Windows Explorer Find Results Highlighter Regular Expressions Margin Indention Matcher Extension Word Wrap with Auto-Indent VSCommands HelpViewerKeywordIndex StyleCop Visual Studio Color Theme Editor PowerCommands for Visual Studio 2010 Extension Analyzer CodeCompare Team Founder Server Power Tools VS10x Selection Popup Color Picker Completion Numbered Bookmarks   Technorati Tags: Visual Studio,Extensions

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  • LINQ 2 Entities , howto check DateTime.HasValue within the linq query

    - by Snoop Dogg
    Hi all ... I have this method that is supposed to get the latest messages posted, from the Table (& EntitySet) called ENTRY ///method gets "days" as parameter, used in new TimeSpan(days,0,0,0);!! using (Entities db = new Entities()) { var entries = from ent in db.ENTRY where ent.DATECREATE.Value > DateTime.Today.Subtract(new TimeSpan(days, 0, 0, 0)) select new ForumEntryGridView() { id = ent.id, baslik = ent.header, tarih = ent.entrydate.Value, membername = ent.Member.ToString() }; return entries.ToList<ForumEntryGridView>(); } Here the DATECREATED is Nullable in the database. I cant place "if"s in this query ... any way to check for that? Thx in advance

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  • LINQ: Single vs. First

    - by Paulo Morgado
    I’ve witnessed and been involved in several discussions around the correctness or usefulness of the Single method in the LINQ API. The most common argument is that you are querying for the first element on the result set and an exception will be thrown if there’s more than one element. The First method should be used instead, because it doesn’t throw if the result set has more than one item. Although the documentation for Single states that it returns a single, specific element of a sequence of values, it actually returns THE single, specific element of a sequence of ONE value. One you use the Single method in your code you are asserting that your query will result in a scalar result instead of a result set of arbitrary length. On the other hand, the documentation for First states that it returns the first element of a sequence of arbitrary length. Imagine you want to catch a taxi. You go the the taxi line and catch the FIRST one, no matter how many are there. On the other hand, if you go the the parking lot to get your car, you want the SINGLE one specific car that’s yours. If your “query” “returns” more than one car, it’s an exception. Either because it “returned” not only your car or you happen to have more than one car in that parking lot. In either case, you can only drive one car at once and you’ll need to refine your “query”.

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  • TakeWhile and SkipWhile method in LINQ

    - by vik20000in
     In my last post I talked about how to use the take and the Skip keyword to filter out the number of records that we are fetching. But there is only problem with the take and skip statement. The problem lies in the dependency where by the number of records to be fetched has to be passed to it. Many a times the number of records to be fetched is also based on the query itself. For example if we want to continue fetching records till a certain condition is met on the record set. Let’s say we want to fetch records from the array of number till we get 7. For this kind of query LINQ has exposed the TakeWhile Method.     int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };     var firstNumbersLessThan6 = numbers.TakeWhile(n => n < 7);   In the same way we can also use the SkipWhile statement. The skip while statement will skip all the records that do not match certain condition provided. In the example below we are skiping all those number which are not divisible by 3. Remember we could have done this with where clause also, but SkipWhile method can be useful in many other situation and hence the example and the keyword.     int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };     var allButFirst3Numbers = numbers.SkipWhile(n => n % 3 != 0); Vikram

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  • Retrieving only the first record or record at a certain index in LINQ

    - by vik20000in
    While working with data it’s not always required that we fetch all the records. Many a times we only need to fetch the first record, or some records in some index, in the record set. With LINQ we can get the desired record very easily with the help of the provided element operators. Simple get the first record. If you want only the first record in record set we can use the first method [Note that this can also be done easily done with the help of the take method by providing the value as one].     List<Product> products = GetProductList();      Product product12 = (         from prod in products         where prod.ProductID == 12         select prod)         .First();   We can also very easily put some condition on which first record to be fetched.     string[] strings = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };     string startsWithO = strings.First(s => s[0] == 'o');  In the above example the result would be “one” because that is the first record starting with “o”.  Also the fact that there will be chances that there are no value returned in the result set. When we know such possibilities we can use the FirstorDefault() method to return the first record or incase there are no records get the default value.        int[] numbers = {};     int firstNumOrDefault = numbers.FirstOrDefault();  In case we do not want the first record but the second or the third or any other later record then we can use the ElementAt() method. In the ElementAt() method we need to pass the index number for which we want the record and we will receive the result for that element.      int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };      int fourthLowNum = (         from num in numbers         where num > 5         select num )         .ElementAt(1); Vikram

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  • What can map database tables like LINQ to SQL did?

    - by trnTash
    A good thing in LINQ to SQL was a fast and reliable way to map database tables and convert them into classes accessible from c# project. However it is no longer recommended to create projects using LINQ to SQL. What is its substitute? What kind of tool should I use in VS 2010 today if I want to have the same functionality as I had with LINQ to SQL?

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  • Retrieving recent tweets using LINQ

    - by brian_ritchie
    There are a few different APIs for accessing Twitter from .NET.  In this example, I'll use linq2twitter.  Other APIs can be found on Twitter's development site. First off, we'll use the LINQ provider to pull in the recent tweets. .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: Consolas, "Courier New", Courier, Monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } 1: public static Status[] GetLatestTweets(string screenName, int numTweets) 2: { 3: try 4: { 5: var twitterCtx = new LinqToTwitter.TwitterContext(); 6: var list = from tweet in twitterCtx.Status 7: where tweet.Type == StatusType.User && 8: tweet.ScreenName == screenName 9: orderby tweet.CreatedAt descending 10: select tweet; 11: // using Take() on array because it was failing against the provider 12: var recentTweets = list.ToArray().Take(numTweets).ToArray(); 13: return recentTweets; 14: } 15: catch 16: { 17: return new Status[0]; 18: } 19: } Once they have been retrieved, they would be placed inside an MVC model. Next, the tweets need to be formatted for display. I've defined an extension method to aid with date formatting: .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: Consolas, "Courier New", Courier, Monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } 1: public static class DateTimeExtension 2: { 3: public static string ToAgo(this DateTime date2) 4: { 5: DateTime date1 = DateTime.Now; 6: if (DateTime.Compare(date1, date2) >= 0) 7: { 8: TimeSpan ts = date1.Subtract(date2); 9: if (ts.TotalDays >= 1) 10: return string.Format("{0} days", (int)ts.TotalDays); 11: else if (ts.Hours > 2) 12: return string.Format("{0} hours", ts.Hours); 13: else if (ts.Hours > 0) 14: return string.Format("{0} hours, {1} minutes", 15: ts.Hours, ts.Minutes); 16: else if (ts.Minutes > 5) 17: return string.Format("{0} minutes", ts.Minutes); 18: else if (ts.Minutes > 0) 19: return string.Format("{0} mintutes, {1} seconds", 20: ts.Minutes, ts.Seconds); 21: else 22: return string.Format("{0} seconds", ts.Seconds); 23: } 24: else 25: return "Not valid"; 26: } 27: } Finally, here is the piece of the view used to render the tweets. .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: Consolas, "Courier New", Courier, Monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } 1: <ul class="tweets"> 2: <% 3: foreach (var tweet in Model.Tweets) 4: { 5: %> 6: <li class="tweets"> 7: <span class="tweetTime"><%=tweet.CreatedAt.ToAgo() %> ago</span>: 8: <%=tweet.Text%> 9: </li> 10: <%} %> 11: </ul>  

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  • LINQ – SequenceEqual() method

    - by nmarun
    I have been looking at LINQ extension methods and have blogged about what I learned from them in my blog space. Next in line is the SequenceEqual() method. Here’s the description about this method: “Determines whether two sequences are equal by comparing the elements by using the default equality comparer for their type.” Let’s play with some code: 1: int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 2: // int[] numbersCopy = numbers; 3: int[] numbersCopy = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 4:  5: Console.WriteLine(numbers.SequenceEqual(numbersCopy)); This gives an output of ‘True’ – basically compares each of the elements in the two arrays and returns true in this case. The result is same even if you uncomment line 2 and comment line 3 (I didn’t need to say that now did I?). So then what happens for custom types? For this, I created a Product class with the following definition: 1: class Product 2: { 3: public int ProductId { get; set; } 4: public string Name { get; set; } 5: public string Category { get; set; } 6: public DateTime MfgDate { get; set; } 7: public Status Status { get; set; } 8: } 9:  10: public enum Status 11: { 12: Active = 1, 13: InActive = 2, 14: OffShelf = 3, 15: } In my calling code, I’m just adding a few product items: 1: private static List<Product> GetProducts() 2: { 3: return new List<Product> 4: { 5: new Product 6: { 7: ProductId = 1, 8: Name = "Laptop", 9: Category = "Computer", 10: MfgDate = new DateTime(2003, 4, 3), 11: Status = Status.Active, 12: }, 13: new Product 14: { 15: ProductId = 2, 16: Name = "Compact Disc", 17: Category = "Water Sport", 18: MfgDate = new DateTime(2009, 12, 3), 19: Status = Status.InActive, 20: }, 21: new Product 22: { 23: ProductId = 3, 24: Name = "Floppy", 25: Category = "Computer", 26: MfgDate = new DateTime(1993, 3, 7), 27: Status = Status.OffShelf, 28: }, 29: }; 30: } Now for the actual check: 1: List<Product> products1 = GetProducts(); 2: List<Product> products2 = GetProducts(); 3:  4: Console.WriteLine(products1.SequenceEqual(products2)); This one returns ‘False’ and the reason is simple – this one checks for reference equality and the products in the both the lists get different ‘memory addresses’ (sounds like I’m talking in ‘C’). In order to modify this behavior and return a ‘True’ result, we need to modify the Product class as follows: 1: class Product : IEquatable<Product> 2: { 3: public int ProductId { get; set; } 4: public string Name { get; set; } 5: public string Category { get; set; } 6: public DateTime MfgDate { get; set; } 7: public Status Status { get; set; } 8:  9: public override bool Equals(object obj) 10: { 11: return Equals(obj as Product); 12: } 13:  14: public bool Equals(Product other) 15: { 16: //Check whether the compared object is null. 17: if (ReferenceEquals(other, null)) return false; 18:  19: //Check whether the compared object references the same data. 20: if (ReferenceEquals(this, other)) return true; 21:  22: //Check whether the products' properties are equal. 23: return ProductId.Equals(other.ProductId) 24: && Name.Equals(other.Name) 25: && Category.Equals(other.Category) 26: && MfgDate.Equals(other.MfgDate) 27: && Status.Equals(other.Status); 28: } 29:  30: // If Equals() returns true for a pair of objects 31: // then GetHashCode() must return the same value for these objects. 32: // read why in the following articles: 33: // http://geekswithblogs.net/akraus1/archive/2010/02/28/138234.aspx 34: // http://stackoverflow.com/questions/371328/why-is-it-important-to-override-gethashcode-when-equals-method-is-overriden-in-c 35: public override int GetHashCode() 36: { 37: //Get hash code for the ProductId field. 38: int hashProductId = ProductId.GetHashCode(); 39:  40: //Get hash code for the Name field if it is not null. 41: int hashName = Name == null ? 0 : Name.GetHashCode(); 42:  43: //Get hash code for the ProductId field. 44: int hashCategory = Category.GetHashCode(); 45:  46: //Get hash code for the ProductId field. 47: int hashMfgDate = MfgDate.GetHashCode(); 48:  49: //Get hash code for the ProductId field. 50: int hashStatus = Status.GetHashCode(); 51: //Calculate the hash code for the product. 52: return hashProductId ^ hashName ^ hashCategory & hashMfgDate & hashStatus; 53: } 54:  55: public static bool operator ==(Product a, Product b) 56: { 57: // Enable a == b for null references to return the right value 58: if (ReferenceEquals(a, b)) 59: { 60: return true; 61: } 62: // If one is null and the other not. Remember a==null will lead to Stackoverflow! 63: if (ReferenceEquals(a, null)) 64: { 65: return false; 66: } 67: return a.Equals((object)b); 68: } 69:  70: public static bool operator !=(Product a, Product b) 71: { 72: return !(a == b); 73: } 74: } Now THAT kinda looks overwhelming. But lets take one simple step at a time. Ok first thing you’ve noticed is that the class implements IEquatable<Product> interface – the key step towards achieving our goal. This interface provides us with an ‘Equals’ method to perform the test for equality with another Product object, in this case. This method is called in the following situations: when you do a ProductInstance.Equals(AnotherProductInstance) and when you perform actions like Contains<T>, IndexOf() or Remove() on your collection Coming to the Equals method defined line 14 onwards. The two ‘if’ blocks check for null and referential equality using the ReferenceEquals() method defined in the Object class. Line 23 is where I’m doing the actual check on the properties of the Product instances. This is what returns the ‘True’ for us when we run the application. I have also overridden the Object.Equals() method which calls the Equals() method of the interface. One thing to remember is that anytime you override the Equals() method, its’ a good practice to override the GetHashCode() method and overload the ‘==’ and the ‘!=’ operators. For detailed information on this, please read this and this. Since we’ve overloaded the operators as well, we get ‘True’ when we do actions like: 1: Console.WriteLine(products1.Contains(products2[0])); 2: Console.WriteLine(products1[0] == products2[0]); This completes the full circle on the SequenceEqual() method. See the code used in the article here.

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  • Why does Linq to Entity Sum return null when the list is empty?

    - by Hannele
    There are quite a few questions on Stack Overflow about the Linq to Entity / Linq to SQL Sum extension method, about how it returns null when the result set is empty: 1, 2, 3, 4, 5, 6, 7, and many more, as well as a blog post discussing the issue here. Now, I could go a flag these as duplicates, but I feel it is still an inconsistency in the Linq implementation. I am assuming at this point that it is not a bug, but is more or less working as designed. I understand that there are workarounds (for example, casting the field to a nullable type, so you can coalesce with ??), and I also understand that for the underlying SQL, a NULL result is expected for an empty list. But because the result of the Sum extension for nullable types is also not nullable, why would the Linq to SQL / Linq to Entity Sum have been designed to behave this way?

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  • Why does Linq to Entity Sum return null when the result set is empty?

    - by Hannele
    There are quite a few questions on Stack Overflow about the Linq to Entity / Linq to SQL Sum extension method, about how it returns null when the result set is empty: 1, 2, 3, 4, 5, 6, 7, and many more, as well as a blog post discussing the issue here. I feel it is an inconsistency in the Linq implementation. I am assuming at this point that it is not a bug, but is more or less working as designed. I understand that there are workarounds (for example, casting the field to a nullable type, so you can coalesce with ??), and I also understand that for the underlying SQL, a NULL result is expected for an empty result set. But because the result of the Sum extension for non-nullable types is also non-nullable, why does the Linq to SQL / Linq to Entity Sum behave this way?

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  • Save Web Content Directly to Google Drive in Chrome [Extension]

    - by Asian Angel
    Are you looking for a quick and easy way to save images, documents, and more directly to Google Drive while browsing? Then you may want to grab a copy of the ‘Save to Google Drive’ extension for Chrome. Once you have installed the extension it is very easy to start saving all that wonderful web content to your Google Drive account via the Context Menu or the Toolbar Button as seen in the screenshot above. One thing to keep in mind is that the first time you use the extension you will be asked for permission to access your account as seen in the screenshot below. Here is a quick look at the options currently available for the extension… Secure Yourself by Using Two-Step Verification on These 16 Web Services How to Fix a Stuck Pixel on an LCD Monitor How to Factory Reset Your Android Phone or Tablet When It Won’t Boot

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  • How to eager load sibling data using LINQ to SQL?

    - by Scott
    The goal is to issue the fewest queries to SQL Server using LINQ to SQL without using anonymous types. The return type for the method will need to be IList<Child1>. The relationships are as follows: Parent Child1 Child2 Grandchild1 Parent Child1 is a one-to-many relationship Child1 Grandchild1 is a one-to-n relationship (where n is zero to infinity) Parent Child2 is a one-to-n relationship (where n is zero to infinity) I am able to eager load the Parent, Child1 and Grandchild1 data resulting in one query to SQL Server. This query with load options eager loads all of the data, except the sibling data (Child2): DataLoadOptions loadOptions = new DataLoadOptions(); loadOptions.LoadWith<Child1>(o => o.GrandChild1List); loadOptions.LoadWith<Child1>(o => o.Parent); dataContext.LoadOptions = loadOptions; IQueryable<Child1> children = from child in dataContext.Child1 select child; I need to load the sibling data as well. One approach I have tried is splitting the query into two LINQ to SQL queries and merging the result sets together (not pretty), however upon accessing the sibling data it is lazy loaded anyway. Adding the sibling load option will issue a query to SQL Server for each Grandchild1 and Child2 record (which is exactly what I am trying to avoid): DataLoadOptions loadOptions = new DataLoadOptions(); loadOptions.LoadWith<Child1>(o => o.GrandChild1List); loadOptions.LoadWith<Child1>(o => o.Parent); loadOptions.LoadWith<Parent>(o => o.Child2List); dataContext.LoadOptions = loadOptions; IQueryable<Child1> children = from child in dataContext.Child1 select child; exec sp_executesql N'SELECT * FROM [dbo].[Child2] AS [t0] WHERE [t0].[ForeignKeyToParent] = @p0',N'@p0 int',@p0=1 exec sp_executesql N'SELECT * FROM [dbo].[Child2] AS [t0] WHERE [t0].[ForeignKeyToParent] = @p0',N'@p0 int',@p0=2 exec sp_executesql N'SELECT * FROM [dbo].[Child2] AS [t0] WHERE [t0].[ForeignKeyToParent] = @p0',N'@p0 int',@p0=3 exec sp_executesql N'SELECT * FROM [dbo].[Child2] AS [t0] WHERE [t0].[ForeignKeyToParent] = @p0',N'@p0 int',@p0=4 I've also written LINQ to SQL queries to join in all of the data in hopes that it would eager load the data, however when the LINQ to SQL EntitySet of Child2 or Grandchild1 are accessed it lazy loads the data. The reason for returning the IList<Child1> is to hydrate business objects. My thoughts are I am either: Approaching this problem the wrong way. Have the option of calling a stored procedure? My organization should not be using LINQ to SQL as an ORM? Any help is greatly appreciated. Thank you, -Scott

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