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  • Reduce the number of queries in EF

    - by Gio2k
    I have the following Model: Entities: Product (Contains basic data for products: price, etc) Attribute (Contains data for all possible optional attributes) ProductAttribute (Contains data for optional attributes of a product, eg. Color, Model, Size). ProductAttribute is essentially a many to many relationship with payload (ProductId, AttributeID, Value) And this piece of code: private static void ListAttributes(Product p) { p.ProductAttributes.Load(); foreach (var att in p.ProductAttributes) { att.Attribute.load(); Console.WriteLine("\tAttribute Name:{0} - Value {1}", att.Attribute.Name, att.AttributeValue); } } This piece of code will fire a query for each time the att.Attribute.Load() method is called in the foreach loop, only so i can get display the name of the attribute. I would like to fetch the Attribute.Name together with the query that fetches all attribute values, i.e. join ProductAttribute and Attribute. Is there any way to achieve this within my method?

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  • Using CreateSourceQuery in CTP4 Code First

    - by Adam Rackis
    I'm guessing this is impossible, but I'll throw it out there anyway. Is it possible to use CreateSourceQuery when programming with the EF4 CodeFirst API, in CTP4? I'd like to eagerly load properties attached to a collection of properties, like this: var sourceQuery = this.CurrentInvoice.PropertyInvoices.CreateSourceQuery(); sourceQuery.Include("Property").ToList(); But of course CreateSourceQuery is defined on EntityCollection<T>, whereas CodeFirst uses plain old ICollection (obviously). Is there some way to convert? I've gotten the below to work, but it's not quite what I'm looking for. Anyone know how to go from what's below to what's above (code below is from a class that inherits DbContext)? ObjectSet<Person> OSPeople = base.ObjectContext.CreateObjectSet<Person>(); OSPeople.Include(Pinner => Pinner.Books).ToList(); Thanks! EDIT: here's my version of the solution posted by zeeshanhirani - who's book by the way is amazing! dynamic result; if (invoice.PropertyInvoices is EntityCollection<PropertyInvoice>) result = (invoices.PropertyInvoices as EntityCollection<PropertyInvoice>).CreateSourceQuery().Yadda.Yadda.Yadda else //must be a unit test! result = invoices.PropertyInvoices; return result.ToList(); EDIT2: Ok, I just realized that you can't dispatch extension methods whilst using dynamic. So I guess we're not quite as dynamic as Ruby, but the example above is easily modifiable to comport with this restriction EDIT3: As mentioned in zeeshanhirani's blog post, this only works if (and only if) you have change-enabled proxies, which will get created if all of your properties are declared virtual. Here's another version of what the method might look like to use CreateSourceQuery with POCOs public class Person { public virtual int ID { get; set; } public virtual string FName { get; set; } public virtual string LName { get; set; } public virtual double Weight { get; set; } public virtual ICollection<Book> Books { get; set; } } public class Book { public virtual int ID { get; set; } public virtual string Title { get; set; } public virtual int Pages { get; set; } public virtual int OwnerID { get; set; } public virtual ICollection<Genre> Genres { get; set; } public virtual Person Owner { get; set; } } public class Genre { public virtual int ID { get; set; } public virtual string Name { get; set; } public virtual Genre ParentGenre { get; set; } public virtual ICollection<Book> Books { get; set; } } public class BookContext : DbContext { public void PrimeBooksCollectionToIncludeGenres(Person P) { if (P.Books is EntityCollection<Book>) (P.Books as EntityCollection<Book>).CreateSourceQuery().Include(b => b.Genres).ToList(); }

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  • Would you make this method Static or not?

    - by Adam Drummond
    During a code review I presented a method quickly to the team that I had made static and one person agreed that there was no reason for it to not be static and a person disagreed saying that he would not make it static because it wasn't necessary and just to be on the safe side for future modifications and testing. So I did quite a bit of research and obviously it's a specialized case but I would like to know what you would do in this situation and why? (Its basically a helper method I call from a few different methods, a very low traffic page. More for my knowledge and learning on Static.) private IEnumerable<Category> GetCategoryByID(int id, Context context) { var categoryQuery = from selectAllProc in context.SelectAll_sp() where selectAllProc.CategoryID == id select selectAllProc; return categoryQuery; }

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  • Problem in mutiple :dependent=> :destroy when multiple polymorphic is true

    - by piemesons
    I have four models question, answer, comment and vote.Consider it same as stackoverflow. Question has_many comments Answers has_many comments Questions has_many votes answers has_many votes comments has_many votes Here are the models (only relevant things) class Comment < ActiveRecord::Base belongs_to :commentable, :polymorphic => true has_many :votes, :as => :votable, :dependent => :destroy end class Question < ActiveRecord::Base has_many :comments, :as => :commentable, :dependent => :destroy has_many :answers, :dependent => :destroy has_many :votes, :as => :votable, :dependent => :destroy end class Vote < ActiveRecord::Base belongs_to :votable, :polymorphic => true end class Answer < ActiveRecord::Base belongs_to :question, :counter_cache => true has_many :comments, :as => :commentable , :dependent => :destroy end Now the problem is whenever i am trying to delete any question/answer/comment its giving me an error NoMethodError in QuestionsController#destroy undefined method `each' for 0:Fixnum if i remove this line from any of the model (question/answer/comment) has_many :votes, :as => :votable, :dependent => :destroy then it works perfectly. It seems there is a problem while deleting the records active record is not able to find out the proper path because of multiple joins within the tables.

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  • Why doesn't this CompiledQuery give a performance improvement?

    - by Grammarian
    I am trying to speed up an often used query. Using a CompiledQuery seemed to be the answer. But when I tried the compiled version, there was no difference in performance between the compiled and non-compiled versions. Can someone please tell me why using Queries.FindTradeByTradeTagCompiled is not faster than using Queries.FindTradeByTradeTag? static class Queries { // Pre-compiled query, as per http://msdn.microsoft.com/en-us/library/bb896297 private static readonly Func<MyEntities, int, IQueryable<Trade>> mCompiledFindTradeQuery = CompiledQuery.Compile<MyEntities, int, IQueryable<Trade>>( (entities, tag) => from trade in entities.TradeSet where trade.trade_tag == tag select trade); public static Trade FindTradeByTradeTagCompiled(MyEntities entities, int tag) { IQueryable<Trade> tradeQuery = mCompiledFindTradeQuery(entities, tag); return tradeQuery.FirstOrDefault(); } public static Trade FindTradeByTradeTag(MyEntities entities, int tag) { IQueryable<Trade> tradeQuery = from trade in entities.TradeSet where trade.trade_tag == tag select trade; return tradeQuery.FirstOrDefault(); } }

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  • data filter using dataloadoptions

    - by Tassadaque
    Using dataloadoptions i have tried the following example Northwnd db = new Northwnd(@"northwnd.mdf"); // Preload Orders for Customer. // One directive per relationship to be preloaded. DataLoadOptions ds = new DataLoadOptions(); ds.LoadWith<Customer>(c => c.Orders); ds.AssociateWith<Customer> (c => c.Orders.Where(p => p.ShippedDate != DateTime.Today)); db.LoadOptions = ds; var custQuery = from cust in db.Customers where cust.City == "London" select cust; foreach (Customer custObj in custQuery) { Console.WriteLine("Customer ID: {0}", custObj.CustomerID); foreach (Order ord in custObj.Orders) { Console.WriteLine("\tOrder ID: {0}", ord.OrderID); foreach (OrderDetail detail in ord.OrderDetails) { Console.WriteLine("\t\tProduct ID: {0}", detail.ProductID); } } } Now i need to ask how can i display Category ID and Category Name of the productID (i am supposing that One product can be in at most one category) by extending the above example Regards

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  • How do I differentiate between different descendents with the same name?

    - by zotty
    I've got some XML I'm trying to import with c#, which looks something like this: <run> <name = "bob"/> <date = "1958"/> </run> <run> <name = "alice"/> <date = "1969"/> </run> I load my xml using XElement xDoc=XElement.Load(filename); What I want to do is have a class for "run", under which I can store names and dates: public class RunDetails { public RunDetails(XElement xDoc, XNamespace xmlns) { var query = from c in xDoc.Descendants(xmlns + "run").Descendants(xmlns + "name") select c; int i=0; foreach (XElement a in query) { this.name= new NameStr(a, xmlns); // a class for names Name.Add(this.name); //Name is a List<NameStr> i++; } // Here, i=2, but what I want is a new instance of the RunDetails class for each <run> } } How can I set up my code to create a new instance of the RunDetails class for every < run, and to only select the < name and < date inside a given < run?

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  • How can I bind an Enum to a DbType of bit or int?

    - by uriDium
    Hi I am using Linq2Sql and want to bind an objects field (which is enum) to either a bit or a int type in the database. For example I want have a gender field in my model. I have already edited the DBML and changed the Type to point to my enum. I want to create Radio buttons (which I think I have figured out) for gender and dropdown lists for other areas using the same idea. My enum looks like this public enum Gender { Male, Female } Mapping between DbType 'int' and Type 'Project.Models.Gender' in Column 'Gender' of Type 'Candidate' is not supported. Any ideas on how to do this mapping. Am I missing something on the enums.

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  • ASP.NET MVC Inserting object and related object into 2 tables

    - by ile
    I have two tables: Users and UserOwners. Table UserOwners contains list of users that certain user created (list of child-users) - or to be more precise, it contains UserOwnerID and UserID fields. So, now I want to create a new user... in Controller I have something like this: var userOwner = accountRepository.GetUser(User.Identity.Name); var userOwnerID = userOwner.UserID; UserReference userReference = new UserReference(); userReference.UserOwnerID = userOwnerID; if (ModelState.IsValid) { try { //accountRepository.Add(user); //accountRepository.Save(); return View(); } catch { return View(); } } What is the easiest way to add new user to a table Users and matching UserOwner to UserOwners table. Is it suppose to be something like this? public void Add(User user) { db.Users.InsertOnSubmit(user); db.UserReferences.InsertOnSubmit(user.UserReference); } ...or I will have to pass two objects and after adding user I must read it's ID and than assign it to userReference object and add that object to DB? If so, how to read ID of the last object added? Thanks, Ile

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  • em.createQuery keeps returning null

    - by Developer106
    I have this application which i use JSF 2.0 and EclipseLink, i have entities created for a database made in MySQL, Created these entities using netbeans 7.1.2, it gets created automaticly. Then i use session beans to work with these entities, the thing is the em.createQuery always returns a null, though I checked NamedQueries in the entities and they perfectly match a sample from the entities named queries:- @NamedQueries({ @NamedQuery(name = "Users.findAll", query = "SELECT u FROM Users u"), @NamedQuery(name = "Users.findByUserId", query = "SELECT u FROM Users u WHERE u.userId = :userId"), @NamedQuery(name = "Users.findByUsername", query = "SELECT u FROM Users u WHERE u.username = :username"), @NamedQuery(name = "Users.findByEmail", query = "SELECT u FROM Users u WHERE u.email = :email"), notice how i use this findByEmail query in the session bean :- public Users findByEmail(String email){ em.getTransaction().begin(); String find = "Users.findByEmail"; Query query = em.createNamedQuery(find); query.setParameter("email", email); Users user = (Users) query.getSingleResult(); but it always returns null from this em.createNamedQuery, i tried using .createQuery first but it also was no good. the stacktrace of the exception Caused by: java.lang.NullPointerException at com.readme.entities.sessionBeans.UsersFacade.findByEmail(UsersFacade.java:48) at com.readme.user.signup.SignupBean.checkAvailability(SignupBean.java:137) at com.readme.user.signup.SignupBean.save(SignupBean.java:146) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) What Seems To Be The Problem Here ?

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  • Merging ILists to bind on datagridview to avoid using a database view

    - by P.Bjorklund
    In the form we have this where IntaktsBudgetsType is a poorly named enum that only specifies wether to populate the datagridview after customer or product (You do the budgeting either after product or customer) private void UpdateGridView() { bs = new BindingSource(); bs.DataSource = intaktsbudget.GetDataSource(this.comboBoxKundID.Text, IntaktsBudgetsType.PerKund); dataGridViewIntaktPerKund.DataSource = bs; } This populates the datagridview with a database view that merge the product, budget and customer tables. The logic has the following method to get the correct set of IList from the repository which only does GetTable<T>.ToList<T> public IEnumerable<IntaktsBudgetView> GetDataSource(string id, IntaktsBudgetsType type) { IList<IntaktsBudgetView> list = repository.SelectTable<IntaktsBudgetView>(); switch (type) { case IntaktsBudgetsType.PerKund: return from i in list where i.kundId == id select i; case IntaktsBudgetsType.PerProdukt: return from i in list where i.produktId == id select i; } return null; } Now I don't want to use a database view since that is read-only and I want to be able to perform CRUD actions on the datagridview. I could build a class that acts as a wrapper for the whole thing and bind the different table values to class properties but that doesn't seem quite right since I would have to do this for every single thing that requires "the merge". Something pretty important (and probably basic) is missing the the thought process but after spending a weekend on google and in books I give up and turn to the SO community.

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  • VB.NET logical expression evaluator

    - by Tim
    I need to test a logical expression held in a string to see if it evaluate to TRUE or FALSE.(the strig is built dynamically) For example the resulting string may contain "'dog'<'cat' OR (14 AND 4<6)". There are no variables in the string, it will logically evaluate. It will only contain simple operators = < < = <= and AND , OR and Open and Close Brackets, string constants and numbers. (converted to correct syntax && || etc.) I currently acheive this by creating a jscipt function and compiling it into a .dll. I then reference the .dll in my VB.NET project. class ExpressionEvaluator { function Evaluate(Expression : String) { return eval(Expression); } } Is there a simpler method using built in .NET functions or Lamdba expressions.

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  • Is it possible to load an entire SQL Server CE database into RAM?

    - by DanM
    I'm using LinqToSql to query a small SQL Server CE database. I've noticed that any operations involving sub-properties are disappointingly slow. For example, if I have a Customer table that is referenced by an Order table via a foreign key, LinqToSql will automatically create an EntitySet<Order> property. This is a nice convenience, allowing me to do things like Customer.Order.Where(o => o.ProductName = "Stopwatch"), but for some reason, SQL Server CE hangs up pretty bad when I try to do stuff like this. One of my queries, which isn't really that complicated takes 3-4 seconds to complete. I can get the speed up to acceptable, even fast, if I just grab the two tables individually and convert them to List<Customer> and List<Order>, then join then manually with my own query, but this is throwing out a lot of the appeal of LinqToSql. So, I'm wondering if I can somehow get the whole database into RAM and just query that way, then occasionally save it. Is this possible? How? If not, is there anything else I can do to boost the performance? Note: My database in its initial state is about 250K and I don't expect it to grow to more than 1-2Mb. So, loading the data into RAM certainly wouldn't be a problem from a memory point of view.

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  • How do I use XPath with a default namespace with no prefix?

    - by Scott Stafford
    What is the XPath (in C# API to XDocument.XPathSelectElements(xpath, nsman) if it matters) to query all MyNodes from this document? <?xml version="1.0" encoding="utf-8"?> <configuration> <MyNode xmlns="lcmp" attr="true"> <subnode /> </MyNode> </configuration I tried /configuration/MyNode which is wrong because it ignores the namespace. I tried /configuration/lcmp:MyNode which is wrong because lcmp is the URI, not the prefix. I tried /configuration/{lcmp}MyNode which failed because Additional information: '/configuration/{lcmp}MyNode' has an invalid token. EDIT: I can't use mgr.AddNamespace("df", "lcmp"); as some of the answerers have suggested. That requires that the XML parsing program know all the namespaces I plan to use ahead of time. Since this is meant to be applicable to any source file, I don't know which namespaces to manually add prefixes for. It seems like {my uri} is the XPath syntax, but Microsoft didn't bother implementing that... true?

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  • MVC 1.0 + EF: Does db.EntitySet.where(something) still return all rows in table?

    - by Dale
    In a repository, I do this: public AgenciesDonor FindPrimary(Guid donorId) { return db.AgenciesDonorSet.Include("DonorPanels").Include("PriceAdjustments").Include("Donors").First(x => x.Donors.DonorId == donorId && x.IsPrimary); } then down in another method in the same repository, this: AgenciesDonor oldPrimary = this.FindPrimary(donorId); In the debugger, the resultsview shows all records in that table, but: oldPrimary.Count(); is 1 (which it should be). Why am I seeing all table entries retrieved, and not just 1? I thought row filtering was done in the DB. If db.EntitySet really does fetch everything to the client, what's the right way to keep the client data-lite using EF? Fetching all rows won't scale for what I'm doing.

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  • Open Source - EER Modeling Tool

    - by Nick Fergis
    Is there a good open source or reasonably priced EER modeling tool for MySQL besides MySQL Workbench? I find the MySQL Workbench interface to be clunky. I would like to be able to manage my production schema beginning all design changes in the EER and propogating those out to my schema for created and altered tables. Is anyone use a tool they love to manage their environments in this way? Thanks. - Nick

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  • Getting percentages.

    - by user287798
    Hi, i have got a standing answer in this thread. http://stackoverflow.com/questions/2396203/get-the-count-of-elements-where-candidate-has-won But i am failing to get the percentage, what am i doing wrong. I have the code below. var s4 = from can in allCandidates let noDists= ((from d in root.Elements("Provinces") select d.Attribute("Province").Value).Distinct()).Count() let count = (from winner in (from p in root.Descendants("Province_Data") let maxVotes = (from c in p.Elements("Candidate") select c) .Max(x => ((int)x.Element("votes"))) select (from c in p.Elements("Candidate") select c).Where(x => ((int)x.Element("votes")) == maxVotes) .First().Element("name").Value ) where winner == can select winner).Count() orderby count descending select new { Candidate = can, NumberOfProvincesWon = count,Percentage= (count/noDists)*100}; foreach (var d in s4) Console.WriteLine(" {0}", d.ToString());

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  • List<T> paging asp.net

    - by user1397978
    Using a three-tier architecture, I have a list of objects List<object> careerList = new List<object>(); ModuleDTO module = new ModuleDTO(); careerList = module.getDegreeCodeByQualification(qualificationCode); which I then add to a gridview like so: gridViewMaster.DataSource = careerList; gridViewMaster.DataBind(); What I'd like to do is then enable paging on the gridview. My gridview so far is: <asp:GridView ID="gridViewMaster" runat="server" AutoGenerateColumns="False" GridLines="None" BorderWidth="1px" CellPadding="2" DataKeyNames="Grouping" ForeColor="Black" onrowdatabound="gridViewMaster_RowDataBound" CssClass="mGrid" PagerStyle-CssClass="pgr" AlternatingRowStyle-CssClass="alt" OnPageIndexChanging="gridView_PageIndexChanging" AllowPaging="True" > Is it possible to do enable paging on a list's without having to change that list to a Datatable or Dataview? If there is a way, this would help a lot. So far my events are as follows: protected void gridView_PageIndexChanging(object sender, GridViewPageEventArgs e) { gridViewMaster.PageIndex = e.NewPageIndex; List<object> careerList = new List<object>(); ModuleDTO module = new ModuleDTO(); careerList = module.getDegreeCodeByQualification(qualificationCode); ModalProgress.Show(); System.Threading.Thread.Sleep(1000); JobPanel.Visible = true; gridViewMaster.DataSource = careerList.Distinct(); gridViewMaster.DataBind(); } Someone PLEASE HELP ME!!! Thank you

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  • Use DataContext to create schema in an existing blank database file?

    - by jdk
    With a DataContext and a blank file-based database that already exists, is it possible to write the Data Context classes (i.e. the ones I added to the designer) to create the db schema? With a data context I only see the abilities to either: create a new database file and have its structure created at the same time, or to populate data into an existing database having preexisting schema. I'm looking for a hybrid solution between those two worlds. Update 1: My proof that a preexisting db is not compatible with the Data Context CreateDatabase() operation is this error Database 'C:...\App_Data\IntermediateData.mdf' already exists. Choose a different database name. based on this code using (IntermediateClassesDataContext intermediateContext = new IntermediateClassesDataContext(_getIntermediateConn())) { intermediateContext.CreateDatabase(); }

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  • starting a service based on someone's GPL/MIT licensed code

    - by fooyee
    someone wrote a nice framework for developing html5 3d engine. It's GPL/MIT licensed. Do you think it's a good idea to build upon it, and then repackage it and sell it as a service? For eg the framework lets you build 3d environments. so I build on it, maybe add a few features like characters and music in the environment, and turn it into an online game. Is it a feasible idea? Of course, part of the GPL license says that all source code has to be visible to end users. Assuming the web is a winner take all market based on first mover advantage, why care about hiding the source code? It's the product that's being sold that counts.

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  • does this raw sql only one trip to the database or many trips?

    - by Álvaro García
    I gues that I have this sql: string strTSQL = "Begin TRAN delete from MyTable where ID = 1"; string strTSQL = ";delete from MyTable where ID = 2"; string strTSQL = ";delete from MyTable where ID = 3 COMMIT"; using(Entities dbContext = new Entities()) { dbCntext.MyTable.SQLQuery(strTSQL); } This use a transaction in the dataBase, so all the commands are executed or no one. But how I execute it through EF, it does only one trip to the database or many? Thanks.

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