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  • Linq-to-sql Add item and a one-to-many record at once

    - by Oskar Kjellin
    I have a function where I can add articles and users can comment on them. This is done with a one to many relationship like= "commentId=>ArticleId". However when I try to add the comment to the database at the same time as I add the one to many record, the commentId is not known. Like this code: Comment comment = new Comment(); comment.Date = DateTime.UtcNow; comment.Text = text; comment.UserId = userId; db.Comments.InsertOnSubmit(comment); comment.Articles.Add(new CommentsForArticle() { ArticleId = articleId, CommentId = comment.CommentId }); The commentId will be 0 before i press submit. Is there any way arround not having to submit in between or do I simply have to cut out the part where I have a one-to-many relationship and just use a CommentTable with a column like "ArticleId". What is best in a performance perspective? I understand the underlying issue, I just want to know which solution works best.

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  • LINQ to Sql: Insert instead of Update

    - by Christina Mayers
    I am stuck with this problems for a long time now. Everything I try to do is insert a row in my DB if it's new information - if not update the existing one. I've updated many entities in my life before - but what's wrong with this code is beyond me (probably something pretty basic) I guess I can't see the wood for the trees... private Models.databaseDataContext db = new Models.databaseDataContext(); internal void StoreInformations(IEnumerable<EntityType> iEnumerable) { foreach (EntityType item in iEnumerable) { EntityType type = db.EntityType.Where(t => t.Room == item.Room).FirstOrDefault(); if (type == null) { db.EntityType.InsertOnSubmit(item); } else { type.Date = item.Date; type.LastUpdate = DateTime.Now(); type.End = item.End; } } } internal void Save() { db.SubmitChanges(); } Edit: just checked the ChangeSet, there are no updates only inserts. For now I've settled with foreach (EntityType item in iEnumerable) { EntityType type = db.EntityType.Where(t => t.Room == item.Room).FirstOrDefault(); if (type != null) { db.Exams.DeleteOnSubmit(type); } db.EntityType.InsertOnSubmit(item); } but I'd love to do updates and lose these unnecessary delete statements.

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  • how to rotate around each record in linq and show that in view

    - by Sadegh
    Hi, I have four tables in my database and i want to join that's and return record's and show that into searchController! My query is this: public IQueryable PerformSearch(string query) { if (!string.IsNullOrEmpty(query)) { var results = from tbl1 in context.Table1 join tbl2 in context.Table2 on tbl1.Id equals tbl2.Id join tbl3 in context.Table3 on tbl2.Id equals tbl3.Id join tbl4 in context.Table4 on tbl3.Id equals tbl4.Id where tbl1.col2.Contains(query) orderby tbl1.Count descending select new { col1 = tbl1.Col1, col1 = tbl1.Col1, col1 = tbl1.Col1, . . . }; return results.AsQueryable(); } else return null; } And this method called in SearchController as below: public class SearchController : System.Web.Mvc.Controller { public System.Web.Mvc.ActionResult Search(System.String query) { var search = new Search(); ViewData["result"] = search.PerformSearch(query); return View("Search"); } } I don't know how i can rotate around each record (plus vs intellisense feature) returned by PeformSeach method and show that in view! Also is this a good way? thanks in advance

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  • Generated sql from LINQ to SQL

    - by Muhammad Kashif Nadeem
    Following code ProductPricesDataContext db = new ProductPricesDataContext(); var products = from p in db.Products where p.ProductFields.Count > 3 select new { ProductIDD = p.ProductId, ProductName = p.ProductName.Contains("hotel"), NumbeOfProd = p.ProductFields.Count, totalFields = p.ProductFields.Sum(o => o.FieldId + o.FieldId) }; Generated follwing sql SELECT [t0].[ProductId] AS [ProductIDD], (CASE WHEN [t0].[ProductName] LIKE '%hotel%' THEN 1 WHEN NOT ([t0].[ProductName] LIKE '%hotel%') THEN 0 ELSE NULL END) AS [ProductName], ( SELECT COUNT(*) FROM [dbo].[ProductField] AS [t2] WHERE [t2].[ProductId] = [t0].[ProductId] ) AS [NumbeOfProd], ( SELECT SUM([t3].[FieldId] + [t3].[FieldId]) FROM [dbo].[ProductField] AS [t3] WHERE [t3].[ProductId] = [t0].[ProductId]) AS [totalFields] FROM [dbo].[Product] AS [t0] WHERE (( SELECT COUNT(*) FROM [dbo].[ProductField] AS [t1] WHERE [t1].[ProductId] = [t0].[ProductId] )) > 3 Why is this CASE statement for ProductName and because of this instead of ProductName i am just getting 0 in my result set. It should generate sql like following, (where ProductName like '%hotel%' SELECT [t0].[ProductId] AS [ProductIDD], [ProductName], ( SELECT COUNT(*) FROM [dbo].[ProductField] AS [t2] WHERE [t2].[ProductId] = [t0].[ProductId] ) AS [NumbeOfProd], ( SELECT SUM([t3].[FieldId] + [t3].[FieldId]) FROM [dbo].[ProductField] AS [t3] WHERE [t3].[ProductId] = [t0].[ProductId]) AS [totalFields] FROM [dbo].[Product] AS [t0] WHERE (( SELECT COUNT(*) FROM [dbo].[ProductField] AS [t1] WHERE [t1].[ProductId] = [t0].[ProductId] )) > 3 AND t0.ProductName like '%hotel%' Thanks.

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  • Linq - How to collect Anonymous Type as Result for a Function

    - by GibboK
    I use c# 4 asp.net and EF 4. I'm precompiling a query, the result should be a collection of Anonymous Type. At the moment I use this code. public static readonly Func<CmsConnectionStringEntityDataModel, string, dynamic> queryContentsList = CompiledQuery.Compile<CmsConnectionStringEntityDataModel, string, dynamic> ( (ctx, TypeContent) => ctx.CmsContents.Where(c => c.TypeContent == TypeContent & c.IsPublished == true & c.IsDeleted == false) .Select(cnt => new { cnt.Title, cnt.TitleUrl, cnt.ContentId, cnt.TypeContent, cnt.Summary } ) .OrderByDescending(c => c.ContentId)); I suspect the RETURN for the FUNCTION Dynamic does not work properly and I get this error Sequence contains more than one element enter code here. I suppose I need to return for my function a Collection of Anonymous Types... Do you have any idea how to do it? What I'm doing wrong? Please post a sample of code thanks! Update: public class ConcTypeContents { public string Title { get; set; } public string TitleUrl { get; set; } public int ContentId { get; set; } public string TypeContent { get; set; } public string Summary { get; set; } } public static readonly Func<CmsConnectionStringEntityDataModel, string, ConcTypeContents> queryContentsList = CompiledQuery.Compile<CmsConnectionStringEntityDataModel, string, ConcTypeContents>( (ctx, TypeContent) => ctx.CmsContents.Where(c => c.TypeContent == TypeContent & c.IsPublished == true & c.IsDeleted == false) .Select(cnt => new ConcTypeContents { cnt.Title, cnt.TitleUrl, cnt.ContentId, cnt.TypeContent, cnt.Summary }).OrderByDescending(c => c.ContentId));

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  • linq delegate function checking from objects

    - by Philip
    I am trying to find the list of objects which can be replaced. Class Letter{ int ID; string Name; string AdvCode; int isDeleted; } Class Replacers{ int ID; string MainAdvCode; string ReplacesAdvCode; } example data: Replacers 0 455 400 1 955 400 2 955 455 such that if a Letter has and Advcode of 455 and another has a code of 400 the 400 gets marked for deletion. And then if another Letter has a 955 then the 455 gets marked for deletion and the 400 (which is already marked) is marked for deletion. The problem is with my current code the 400 and 455 is marking itself for deletion?!?!? Public class Main{ List<Letter> Letters; List<Replacers> replaces; //select the ones to replace the replacements aka the little guys //check if the replacements replacer exists if yes mark deleted var filterMethodReplacements = new Func<Letter, bool>(IsAdvInReplacements);//Working var filterMethodReplacers = new Func<Letter, bool>(IsAdvInReplacers);//NOT WORKING???? var resReplacements=letters.Where(filterMethodReplacements);//working foreach (Letter letter in resReplacements) { //select the Replacers aka the ones that contain the little guys var resReplacers = letters.Where(filterMethodReplacers); if (resReplacers != null) letter.isDeleted = 1; } } } private bool IsAdvInReplacements(Letter letter) { return (from a in Replacables where a.ReplaceAdvCode == letter.AdvCode select a).Any(); } private bool IsAdvInReplacers(Letter letter) { //?????????????????????????????? return (from a in Replacables where a.MainAdvCode == letter.AdvCode select a).Any(); } }

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  • c# Convert LINQ var result to actual type

    - by DrBob
    In c#, Given the following code: public class Person { public int PersonID { get; set; } public int Age { get; set; } public string Name { get; set; } } and List<Person> people = new List<Person>(); for (int i = 0; i != 15; i++) { Person p = new Person(); p.PersonID = i; p.Age = i * 12; p.Name = "Name " + i; people.Add(p); } var sortedPeople = from qPeople in people where qPeople.Age > 0 && qPeople.Age < 25 || qPeople.Age > 100 orderby qPeople.Age descending select qPeople; Can I load the results of sortedPeople back into a List<Person without a loop? Thanks.

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  • Entity framework with Linq to Entities performance

    - by mare
    If I have a static method like this public static string GetTicClassificationTitle(string classI, string classII, string classIII) { using (TicDatabaseEntities ticdb = new TicDatabaseEntities()) { var result = from classes in ticdb.Classifications where classes.ClassI == classI where classes.ClassII == classII where classes.ClassIII == classIII select classes.Description; return result.FirstOrDefault(); } } and use this method in various places in foreach loops or just plain calling it numerous times, does it create and open new connection every time? If so, how can I tackle this? Should I cache the results somewhere, like in this case, I would cache the entire Classifications table in Memory Cache? And then do queries vs this cached object? Or should I make TicDatabaseEntities variable static and initialize it at class level? Should my class be static if it contains only static methods? Because right now it is not.. Also I've noticed that if I return result.First() instead of FirstOrDefault() and the query does not find a match, it will issue an exception (with FirstOrDefault() there is no exception, it returns null). Thank you for clarification.

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  • Storing values in the DataValueField and DataTextField of a dropdownlist using a linq query

    - 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. The code is: private void PopulateDanceDropDown() { // Retrieve the username MembershipUser currentUser = Membership.GetUser(); var username = currentUser.UserName; // Retrive the userid of the curren user var dancerIdFromDB = from d in context.DANCER where d.UserName == username select d.UserId; Guid dancerId = new Guid(); var first = dancerIdFromDB.FirstOrDefault(); if (first != null) { dancerId = first; } dances.DataSource = (from dd in context.DANCER_AND_DANCE where dd.UserId == dancerId select new { Text = dd.DanceName, Value = dd.DanceId }).ToList(); 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); } } The problem is in the line: String strDataValueField = dances.SelectedItem.Value; The strDataValueField is always getting the minimum id from the list of dance item ids in the dropdown (which happens by default). I want this to hold the id of the dance selected by the user.

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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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  • 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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  • Purpose of "new" keyword

    - by Channel72
    The new keyword in languages like Java, Javascript, and C# creates a new instance of a class. This syntax seems to have been inherited from C++, where new is used specifically to allocate a new instance of a class on the heap, and return a pointer to the new instance. In C++, this is not the only way to construct an object. You can also construct an object on the stack, without using new - and in fact, this way of constructing objects is much more common in C++. So, coming from a C++ background, the new keyword in languages like Java, Javascript, and C# seemed natural and obvious to me. Then I started to learn Python, which doesn't have the new keyword. In Python, an instance is constructed simply by calling the constructor, like: f = Foo() At first, this seemed a bit off to me, until it occurred to me that there's no reason for Python to have new, because everything is an object so there's no need to disambiguate between various constructor syntaxes. But then I thought - what's really the point of new in Java? Why should we say Object o = new Object();? Why not just Object o = Object();? In C++ there's definitely a need for new, since we need to distinguish between allocating on the heap and allocating on the stack, but in Java all objects are constructed on the heap, so why even have the new keyword? The same question could be asked for Javascript. In C#, which I'm much less familiar with, I think new may have some purpose in terms of distinguishing between object types and value types, but I'm not sure. Regardless, it seems to me that many languages which came after C++ simply "inherited" the new keyword - without really needing it. It's almost like a vestigial keyword. We don't seem to need it for any reason, and yet it's there. Question: Am I correct about this? Or is there some compelling reason that new needs to be in C++-inspired memory-managed languages like Java, Javascript and C#?

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  • Problem with eager load polymorphic associations using Linq and NHibernate

    - by Voislav
    Is it possible to eagerly load polymorphic association using Linq and NH? For example: Company is base class, Department is inherited from Company, and Company has association Employees to the User (one-to-many) and also association to the Country (many-to-one). Here is mapping part related to inherited class (without User and Country classes): <class name="Company" discriminator-value="Company"> <id name="Id" type="int" unsaved-value="0" access="nosetter.camelcase-underscore"> <generator class="native"></generator> </id> <discriminator column="OrganizationUnit" type="string" length="10" not-null="true"/> <property name="Name" type="string" length="50" not-null="true"/> <many-to-one name="Country" class="Country" column="CountryId" not-null ="false" foreign-key="FK_Company_CountryId" access="field.camelcase-underscore" /> <set name="Departments" inverse="true" lazy="true" access="field.camelcase-underscore"> <key column="DepartmentParentId" not-null="false" foreign-key="FK_Department_DepartmentParentId"></key> <one-to-many class="Department"></one-to-many> </set> <set name="Employees" inverse="true" lazy="true" access="field.camelcase-underscore"> <key column="CompanyId" not-null="false" foreign-key="FK_User_CompanyId"></key> <one-to-many class="User"></one-to-many> </set> <subclass name="Department" extends="Company" discriminator-value="Department"> <many-to-one name="DepartmentParent" class="Company" column="DepartmentParentId" not-null ="false" foreign-key="FK_Department_DepartmentParentId" access="field.camelcase-underscore" /> </subclass> </class> I do not have problem to eagerly load any of the association on the Company: Session.Query<Company>().Where(c => c.Name == "Main Company").Fetch(c => c.Country).Single(); Session.Query<Company>().Where(c => c.Name == "Main Company").FetchMany(c => c.Employees).Single(); Also, I could eagerly load not-polymorphic association on the department: Session.Query<Department>().Where(d => d.Name == "Department 1").Fetch(d => d.DepartmentParent).Single(); But I get NullReferenceException when I try to eagerly load any of the polymorphic association (from the Department): Assert.Throws<NullReferenceException>(() => Session.Query<Department>().Where(d => d.Name == "Department 1").Fetch(d => d.Country).Single()); Assert.Throws<NullReferenceException>(() => Session.Query<Department>().Where(d => d.Name == "Department 1").FetchMany(d => d.Employees).Single()); Am I doing something wrong or this is not supported yet?

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  • Linq to XML Read and output XML generated from lookup list

    - by Greg S
    I am trying to use XML created from a lookup list in SharePoint as a datasource for a treeview. It is in the form of : <NewDataSet> <test_data> <ID>1</ID> <Title>MenuItem_1</Title> <child_of /> </test_data> <test_data> <ID>2</ID> <Title>Subitem_1</Title> <Action>http://www.google.com</Action> <child_of>MenuItem_1</child_of> </test_data> <test_data> <ID>3</ID> <Title>Subitem_2</Title> <Action>http://www.google.com</Action> <child_of>MenuItem_1</child_of> </test_data> <test_data> <ID>4</ID> <Title>MenuItem_2</Title> <child_of /> </test_data> <test_data> <ID>5</ID> <Title>Subitem_2_1</Title> <Action>http://www.google.com</Action> <child_of>MenuItem_2</child_of> </test_data> <test_data> <ID>6</ID> <Title>Subitem_2_2</Title> <Action>http://www.google.com</Action> <child_of>MenuItem_2</child_of> </test_data> <test_data> <ID>7</ID> <Title>Subitem_2_2_1</Title> <Action>http://www.google.com</Action> <child_of>Subitem_2_2</child_of> </test_data> </NewDataSet> There may be N tiers, but the items relate to the parent via the <child_of> element. I can't seem to figure out how to write the LINQ in C# to nest the menu items properly. A friend recommended I post here. Any help is greatly appreciated.

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  • Robust LINQ to XML query for sibling key-value pairs

    - by awshepard
    (First post, please be gentle!) I am just learning about LINQ to XML in all its glory and frailty, trying to hack it to do what I want to do: Given an XML file like this - <list> <!-- random data, keys, values, etc.--> <key>FIRST_WANTED_KEY</key> <value>FIRST_WANTED_VALUE</value> <key>SECOND_WANTED_KEY</key> <value>SECOND_WANTED_VALUE</value> <!-- wanted because it's first --> <key>SECOND_WANTED_KEY</key> <value>UNWANTED_VALUE</value> <!-- not wanted because it's second --> <!-- nonexistent <key>THIRD_WANTED_KEY</key> --> <!-- nonexistent <value>THIRD_WANTED_VALUE</value> --> <!-- more stuff--> </list> I want to extract the values of a set of known "wanted keys" in a robust fashion, i.e. if SECOND_WANTED_KEY appears twice, I only want SECOND_WANTED_VALUE, not UNWANTED_VALUE. Additionally, THIRD_WANTED_KEY may or may not appear, so the query should be able to handle that as well. I can assume that FIRST_WANTED_KEY will appear before other keys, but can't assume anything about the order of the other keys - if a key appears twice, its values aren't important, I only want the first one. An anonymous data type consisting of strings is fine. My attempt has centered around something along these lines: var z = from y in x.Descendants() where y.Value == "FIRST_WANTED_KEY" select new { first_wanted_value = ((XElement)y.NextNode).Value, //... } My question is what should that ... be? I've tried, for instance, (ugly, I know) second_wanted_value = ((XElement)y.ElementsAfterSelf() .Where(w => w.Value=="SECOND_WANTED_KEY") .FirstOrDefault().NextNode).Value which should hopefully allow the key to be anywhere, or non-existent, but that hasn't worked out, since .NextNode on a null XElement doesn't seem to work. I've also tried to add in a .Select(t => { if (t==null) return new XElement("SECOND_WANTED_KEY",""); else return t; }) clause in after the where, but that hasn't worked either. I'm open to suggestions, (constructive) criticism, links, references, or suggestions of phrases to Google for, etc. I've done a fair share of Googling and checking around S.O., so any help would be appreciated. Thanks!

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  • Noob LINQ - reading, filtering XML with XDocument

    - by user316117
    I'm just learning XDocument and LINQ queries. Here's some simple XML (which doesn't look formatted exactly right in this forum in my browser, but you get the idea . . .) <?xml version="1.0" encoding="utf-8"?> <quiz xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.example.com/name XMLFile2.xsd" title="MyQuiz1"> <q_a> <q_a_num>1</q_a_num> <q_>Here is question 1</q_> <_a>Here is the answer to 1</_a> </q_a> <q_a> <q_a_num>2</q_a_num> <q_>Here is question 2</q_> <_a>Here is the answer to 2</_a> </q_a> </quiz> I can iterate across all elements in my XML file and display their Name, Value, and NodeType in a ListBox like this, no problem: XDocument doc = XDocument.Load(sPath); IEnumerable<XElement> elems = doc.Descendants(); IEnumerable<XElement> elem_list = from elem in elems select elem; foreach (XElement element in elem_list) { String str0 = "Name = " + element.Name.ToString() + ", Value = " + element.Value.ToString() + ", Nodetype = " + element.NodeType.ToString(); System.Windows.Controls.Label strLabel = new System.Windows.Controls.Label(); strLabel.Content = str0; listBox1.Items.Add(strLabel); } ...but now I want to add a "where" clause to my query so that I only select elements with a certain name (e.g., "qa") but my element list comes up empty. I tried . . . IEnumerable<XElement> elem_list = from elem in elems where elem.Name.ToString() == "qa" select elem; Could someone please explain what I'm doing wrong? (and in general are there some good tips for debugging Queries?) Thanks in advance!

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  • Ninject with Object Initializers and LINQ

    - by Alexander Kahoun
    I'm new to Ninject so what I'm trying may not even be possible but I wanted to ask. I free-handed the below so there may be typos. Let's say I have an interface: public interface IPerson { string FirstName { get; set; } string LastName { get; set;} string GetFullName(); } And a concrete: public class Person : IPerson { public string FirstName { get; set; } public string LastName { get; set; } public string GetFullName() { return String.Concat(FirstName, " ", LastName); } } What I'm used to doing is something like this when I'm retrieving data from arrays or xml: public IEnumerable<IPerson> GetPeople(string xml) { XElement persons = XElement.Parse(xml); IEnumerable<IPerson> people = ( from person in persons.Descendants("person") select new Person { FirstName = person.Attribute("FName").Value, LastName = person.Attribute("LName").Value }).ToList(); return people; } I don't want to tightly couple the concrete to the interface in this manner. I haven't been able to find any information in regards to using Ninject with LINQ to Objects or with object initializers. I may be looking in the wrong places, but I've been searching for a day now with no luck at all. I was contemplating putting the kernel into an singleton instance and seeing if that would work, but I'm not sure that it will plus I've heard that passing your kernel around is a bad thing. I'm trying to implement this in a class library currently. If this is not possible, does anyone have any examples or suggestions as to what the best practice is in this case? Thanks in advance for the help. EDIT: Based on some of the answers I feel I should clarify. Yes, the example above appears short lived but it was simply an example of one piece that I was trying to do. Let's give a bigger picture. Say instead of XML I am gathering all my data through a 3rd party web service and I'm creating an interface for it, the data could be a defined object in the wsdl or it could sometimes be an xml string. IPerson could be used for both the Person object and a User object. I will be doing this inside of a separate class library, because it needs to be portable and will be used in other projects, and handing it to an MVC3 Web Application and the objects will be used in javascript as well. I appreciate all the input so far.

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  • Having trouble doing an Update with a Linq to Sql object

    - by Pure.Krome
    Hi folks, i've got a simple linq to sql object. I grab it from the database and change a field then save. No rows have been updated. :( When I check the full Sql code that is sent over the wire, I notice that it does an update to the row, not via the primary key but on all the fields via the where clause. Is this normal? I would have thought that it would be easy to update the field(s) with the where clause linking on the Primary Key, instead of where'ing (is that a word :P) on each field. here's the code... using (MyDatabase db = new MyDatabase()) { var boardPost = (from bp in db.BoardPosts where bp.BoardPostId == boardPostId select bp).SingleOrDefault(); if (boardPost != null && boardPost.BoardPostId > 0) { boardPost.ListId = listId; // This changes the value from 0 to 'x' db.SubmitChanges(); } } and here's some sample sql.. exec sp_executesql N'UPDATE [dbo].[BoardPost] SET [ListId] = @p6 WHERE ([BoardPostId] = @p0) AND .... <snip the other fields>',N'@p0 int,@p1 int,@p2 nvarchar(9),@p3 nvarchar(10),@p4 int,@p5 datetime,@p6 int',@p0=1276,@p1=212787,@p2=N'ttreterte',@p3=N'ttreterte3',@p4=1,@p5='2009-09-25 12:32:12.7200000',@p6=72 Now, i know there's a datetime field in this update .. and when i checked the DB it's value was/is '2009-09-25 12:32:12.720' (less zero's, than above) .. so i'm not sure if that is messing up the where clause condition... but still! should it do a where clause on the PK's .. if anything .. for speed! Yes / no ? UPDATE After reading nitzmahone's reply, I then tried playing around with the optimistic concurrency on some values, and it still didn't work :( So then I started some new stuff ... with the optimistic concurrency happening, it includes a where clause on the field it's trying to update. When that happens, it doesn't work. so.. in the above sql, the where clause looks like this ... WHERE ([BoardPostId] = @p0) AND ([ListId] IS NULL) AND ... <rest snipped>) This doesn't sound right! the value in the DB is null, before i do the update. but when i add the ListId value to the where clause (or more to the point, when L2S add's it because of the optomistic concurrecy), it fails to find/match the row. wtf?

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  • get attributes from xml tree using linq

    - by nelsonwebs
    I'm working with an xml file that looks like this: <?xml version="1.0" encoding="UTF-8"?> <element1 xmlns="http://namespace1/"> <element2> <element3> <element4 attr1="2009-11-09"> <element5 attr2="NAME1"> <element6 attr3="1"> <element7 attr4="1" attr5="5.5" attr6="3.4"/> </element6> </element5> <element5 attr2="NAME2"> <element6 attr3="1"> <element7 attr4="3" attr5="4" attr6="4.5"/> </element6> </element5> </element4> </element3> </element2> </element1> Where I need to loop through element5 and retrieve the attributes in an Ienumberable like this: attr1, attr2, attr3, attr4, attr5, attr6 using linq to xml and c#. I can loop through the element5 and get all the attribute2 info using but I can't figure out how to get the parent or child attributes I need. UPDATE: Thanks for the feeback thus far. For clarity, I need to do a loop through attribute5. So basically, what I have right now (which isn't much) is . . . XElement xel = XElement.Load(xml); IEnumberable<XElement> cList = from el in xel.Elements(env + "element2").Element (n2 + "element3").Elements(n2 + "element4").Elements(ns + "element5") select el; foreach (XElement e in cList) Console.WriteLine(e.Attribute("attr2").Value.ToString()); This will give me the value all the attr 2 in the loop but I could be going about this all wrong for what I'm trying to acheive. I also need to collect the other attributes mentioned above in a collection (the Console reference is just me playing with this right now but the end result I need is a collection). So the end results would be a collection like attr1, attr2, attr3, attr4, attr5, attr6 2009-11-09, name1, 1, 1, 5.5, 3.4 2009-11-09, name2, 1, 3, 4, 4.5 Make Sense?

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  • How to create view model without sorting collections in memory.

    - by Chevex
    I have a view model (below). public class TopicsViewModel { public Topic Topic { get; set; } public Reply LastReply { get; set; } } I want to populate an IQueryable<TopicsViewModel> with values from my IQueryable<Topic> collection and IQueryable<Reply> collection. I do not want to use the attached entity collection (i.e. Topic.Replies) because I only want the last reply for that topic and doing Topic.Replies.Last() loads the entire entity collection in memory and then grabs the last one in the list. I am trying to stay in IQueryable so that the query is executed in the database. I also don't want to foreach through topics and query replyRepository.Replies because looping through IQueryable<Topic> will start the lazy loading. I'd prefer to build one expression and have all the leg work done in the lower layers. I have the following: IQueryable<TopicsViewModel> topicsViewModel = from x in topicRepository.Topics from y in replyRepository.Replies where y.TopicID == x.TopicID orderby y.PostedDate ascending select new TopicsViewModel { Topic = x, LastReply = y }; But this isn't working. Any ideas how I can populate an IQueryable or IEnumerable of TopicsViewModel so that it queries the database and grabs topics and that topic's last reply? I am trying really hard to avoid grabbing all replies related to that topic. I only want to grab the last reply. Thank you for any insight you have to offer.

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  • Why is it possible to enumerate a LinqToSql query after calling Dispose() on the DataContext?

    - by DanM
    I'm using the Repository Pattern with some LinqToSql objects. My repository objects all implement IDisposable, and the Dispose() method does only thing--calls Dispose() on the DataContext. Whenever I use a repository, I wrap it in a using person, like this: public IEnumerable<Person> SelectPersons() { using (var repository = _repositorySource.GetNew<Person>(dc => dc.Person)) { return repository.GetAll(); } } This method returns an IEnumerable<Person>, so if my understanding is correct, no querying of the database actually takes place until Enumerable<Person> is traversed (e.g., by converting it to a list or array or by using it in a foreach loop), as in this example: var persons = gateway.SelectPersons(); // Dispose() is fired here var personViewModels = ( from b in persons select new PersonViewModel { Id = b.Id, Name = b.Name, Age = b.Age, OrdersCount = b.Order.Count() }).ToList(); // executes queries In this example, Dispose() gets called immediately after setting persons, which is an IEnumerable<Person>, and that's the only time it gets called. So, a couple questions: How does this work? How can a disposed DataContext still query the database for results when I walk the IEnumerable<Person>? What does Dispose() actually do? I've heard that it is not necessary (e.g., see this question) to dispose of a DataContext, but my impression was that it's not a bad idea. Is there any reason not to dispose of it?

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  • Silverlight: After adding table no datacontext classes are available for the new DomainService class

    - by Gabriel
    I'm using a Silverlight 4 WCF RIA Services demo application that uses LinqToSql, that works well. I add a new database table, move the new table to the LinqToSql designer and build the project I add a new DomainService class I get a dialog with the only option to create an empty DomainService and no DataContext classes are available. What am I missed? Thanks in advance Gabriel

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  • Overriding LINQ extension methods

    - by Ruben Vermeersch
    Is there a way to override extension methods (provide a better implementation), without explicitly having to cast to them? I'm implementing a data type that is able to handle certain operations more efficiently than the default extension methods, but I'd like to keep the generality of IEnumerable. That way any IEnumerable can be passed, but when my class is passed in, it should be more efficient. As a toy example, consider the following: // Compile: dmcs -out:test.exe test.cs using System; namespace Test { public interface IBoat { void Float (); } public class NiceBoat : IBoat { public void Float () { Console.WriteLine ("NiceBoat floating!"); } } public class NicerBoat : IBoat { public void Float () { Console.WriteLine ("NicerBoat floating!"); } public void BlowHorn () { Console.WriteLine ("NicerBoat: TOOOOOT!"); } } public static class BoatExtensions { public static void BlowHorn (this IBoat boat) { Console.WriteLine ("Patched on horn for {0}: TWEET", boat.GetType().Name); } } public class TestApp { static void Main (string [] args) { IBoat niceboat = new NiceBoat (); IBoat nicerboat = new NicerBoat (); Console.WriteLine ("## Both should float:"); niceboat.Float (); nicerboat.Float (); // Output: // NiceBoat floating! // NicerBoat floating! Console.WriteLine (); Console.WriteLine ("## One has an awesome horn:"); niceboat.BlowHorn (); nicerboat.BlowHorn (); // Output: // Patched on horn for NiceBoat: TWEET // Patched on horn for NicerBoat: TWEET Console.WriteLine (); Console.WriteLine ("## That didn't work, but it does when we cast:"); (niceboat as NiceBoat).BlowHorn (); (nicerboat as NicerBoat).BlowHorn (); // Output: // Patched on horn for NiceBoat: TWEET // NicerBoat: TOOOOOT! Console.WriteLine (); Console.WriteLine ("## Problem is: I don't always know the type of the objects."); Console.WriteLine ("## How can I make it use the class objects when the are"); Console.WriteLine ("## implemented and extension methods when they are not,"); Console.WriteLine ("## without having to explicitely cast?"); } } } Is there a way to get the behavior from the second case, without explict casting? Can this problem be avoided?

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  • Where to insert 'orderby' expression in this linq-to-sql query

    - by ile
    var result = db.PhotoAlbums.Select(albums => new PhotoAlbumDisplay { AlbumID = albums.AlbumID, Title = albums.Title, Date = albums.Date, PhotoID = albums.Photos.Select(photo => photo.PhotoID).FirstOrDefault().ToString() }); Wherever I try to put orderby albums.AlbumID descending I get error. Someone knows solution? Thanks!

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  • LINQ - array property contains element from another array

    - by Rob
    I have a object (product), with a property of type 'array' e.g. product.tags = {"tag1","tag2","tag9"} I have an array of input tags to filter on. ... but this is not quite working: List<string> filterTags = new List<string>() { "tag1", "tag3" }; var matches = from p in products where p.Tags.Contains(filterTags) select p; Any recommendations? Thanks.

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