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  • Keeping Linq to SQL alive when using ViewModels (ASP.NET MVC)

    - by Kohan
    I have recently started using custom ViewModels (For example, CustomerViewModel) public class CustomerViewModel { public IList<Customer> Customers{ get; set; } public int ProductId{ get; set; } public CustomerViewModel(IList<Customer> customers, int productId) { this.Customers= customers; this.ProductId= productId; } public CustomerViewModel() { } } ... and am now passing them to my view instead of the Entities themselves (for example, var Custs = repository.getAllCusts(id) ) as it seems good practice to do so. The problem i have encountered is that when using ViewModels; by the time it has got to the the view i have lost the ability to lazy load on customers. I do not believe this was the case before using them. Is it possible to retain the ability of Lazy Loading while still using ViewModels? Or do i have to eager load using this method? Thanks, Kohan.

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  • C# Linq: Can you merge DataContexts?

    - by Andreas Grech
    Say I have one database, and this database has a set of tables that are general to all Clients and some tables that are specific to certain clients. Now what I have in mind is creating a primary DataContext that includes only the tables that are general to all the clients, and then create separate DataContexts that contain only the tables that are specific to the client. Is there a way to kind of "merge" DataContexts so that it becomes one context? So for Client A, I need one DataContext that includes both the general tables and also the tables for that specific client (retrieved from two different DataContexts) ? [Update] What I think I can do is, from the Partial Class of the DataContext instead of letting my DataContext inherit from DataContext I make it inherit from MyDataContext; that way, the tables from MyDataContext and the other DataContext will be available in one DataContext class. What do you think about this approach? Of course with something like this you can only merge two datacontexts at once though...

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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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  • Linq to xml, retreaving generic interface-based list

    - by Rita
    I have an xml document that looks like this <Elements> <Element> <DisplayName /> <Type /> </Element> </Elements> I have an interface, interface IElement { string DisplayName {get;} } and a couple of derived classes: public class AElement: IElement public class BElement: IElement What I want to do, is to write the most efficient query to iterate through the xml and create a list of IElement, containing AElement or BElement, based on the 'Type' property in the xml. So far I have this: IEnumerable<AElement> elements = from xmlElement in XElement.Load(path).Elements("Element") where xmlElement.Element("type").Value == "AElement" select new AElement(xmlElement.Element("DisplayName").Value); return elements.Cast<IElement>().ToList(); But this is only for AElement, is there a way to add BElement in the same query, and also make it generic IEnumerable? Or would I have to run this query once for each derived type?

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  • linq min question/bug

    - by jdelator
    Anyone care to guess what currentIndex is at the end of execution? int[] ints = new int[] { -1, 12, 26, 41, 52, -1, -1 }; int currentIndex = ints.Min(); It's 110. Does anyone know why?

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  • Databinding expression for retrieving value of related collection using LINQ

    - by joshb
    I have a GridView that is bound to a LINQDataSource control that is returning a collection of customers. Within my DataGrid I need to display the home phone number of a customer, if they have one. The phone numbers of a customer are stored in a separate table with a foreign key pointing to the customer table. The following binding expression gets me the first phone number for a customer: <asp:TemplateField HeaderText="LastName" SortExpression="LastName"> <ItemTemplate> <asp:Label ID="PhoneLabel" runat="server" Text='<%# Eval("Phones[0].PhoneNumber") %>'></asp:Label> </ItemTemplate> </asp:TemplateField> I need to figure out how to get the home phone number specifically (filter based on phone type) and handle the scenario where the customer does not have a home phone in the database. Right now it's throwing an out of range exception if the customer does not have any phone numbers. I've tried using the Where operator with a lambda expression to filter the phone type but it doesn't work: <%# Eval("Phones.Where(p => p.PhoneTypeId == 2).PhoneNumber") %> Solutions or links to any good articles on the subject would be much appreciated.

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  • Need help with a Linq XML conditional grouping query

    - by FiveTools
    I have the following xml fragment: <BANNER ID="Banner 2" ROW_WIDTH="200"> <BANNER_TEXTS ID="BANNER_TEXTS"> <BANNER_TEXT UNDERLINE="false" SPAN_COL="1" WIDTHT="78px"></BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="3" WIDTHT="234px">Years In Practice</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="3" WIDTHT="234px">Internet Usage</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="4" WIDTHT="312px">Sales Reps Seen / Week</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="3" WIDTHT="234px">Prescription Volume</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="3" WIDTHT="222px">Patient Load</BANNER_TEXT> </BANNER_TEXTS> <BANNER_TEXTS ID="COLUMN_TEXTS"> <BANNER_TEXT UNDERLINE="true" SPAN_COL="1" WIDTHT="78px">Total</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="1" WIDTHT="78px">&#60; 11 years</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="1" WIDTHT="78px">11-20 years</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="1" WIDTHT="78px">21-30 years</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="1" WIDTHT="78px">Light 1-5 hrs</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="1" WIDTHT="78px">Medium 6-10 hrs</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="1" WIDTHT="78px">Heavy &#62;10 hrs</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="1" WIDTHT="78px">0</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="1" WIDTHT="78px">1-2</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="1" WIDTHT="78px">3-5</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="1" WIDTHT="78px">&#62;5</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="1" WIDTHT="78px">1-100</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="1" WIDTHT="78px">101-150</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="1" WIDTHT="78px">&#62;150</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="1" WIDTHT="74px">1-100</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="1" WIDTHT="74px">101-200</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="1" WIDTHT="74px">&#62;200</BANNER_TEXT> </BANNER_TEXTS> <BANNER_TEXTS ID="COLUMN_TEXTS"> <COLUMN_TEXT UNDERLINE="false" SPAN_COL="1">(A)</COLUMN_TEXT> <COLUMN_TEXT UNDERLINE="false" SPAN_COL="1">(B)</COLUMN_TEXT> <COLUMN_TEXT UNDERLINE="false" SPAN_COL="1">(C)</COLUMN_TEXT> <COLUMN_TEXT UNDERLINE="false" SPAN_COL="1">(D)</COLUMN_TEXT> <COLUMN_TEXT UNDERLINE="false" SPAN_COL="1">(E)</COLUMN_TEXT> <COLUMN_TEXT UNDERLINE="false" SPAN_COL="1">(F)</COLUMN_TEXT> <COLUMN_TEXT UNDERLINE="false" SPAN_COL="1">(G)</COLUMN_TEXT> <COLUMN_TEXT UNDERLINE="false" SPAN_COL="1">(H)</COLUMN_TEXT> <COLUMN_TEXT UNDERLINE="false" SPAN_COL="1">(I)</COLUMN_TEXT> <COLUMN_TEXT UNDERLINE="false" SPAN_COL="1">(J)</COLUMN_TEXT> <COLUMN_TEXT UNDERLINE="false" SPAN_COL="1">(K)</COLUMN_TEXT> <COLUMN_TEXT UNDERLINE="false" SPAN_COL="1">(L)</COLUMN_TEXT> <COLUMN_TEXT UNDERLINE="false" SPAN_COL="1">(M)</COLUMN_TEXT> <COLUMN_TEXT UNDERLINE="false" SPAN_COL="1">(N)</COLUMN_TEXT> <COLUMN_TEXT UNDERLINE="false" SPAN_COL="1">(O)</COLUMN_TEXT> <COLUMN_TEXT UNDERLINE="false" SPAN_COL="1">(P)</COLUMN_TEXT> <COLUMN_TEXT UNDERLINE="false" SPAN_COL="1">(Q)</COLUMN_TEXT> </BANNER_TEXTS> </BANNER> I would like to group all the 'BANNER_TEXT' in the second sequence using the first sequence 'BANNER_TEXT' as the key (only include elements where string is not null or empty). The span_col attribute in the first 'BANNER_TEXT' sequence indicates which elements by position in the 2nd sequence are related. An example: 'Years in Practice' would be the first key and the attribute SPAN_COL=3 for that element indicates it would contain '< 11 years', '11-20 years', '21-30 years' (the first grouping of string.empty = Total would be skipped).

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  • LINQ transform Dictionary<key,value> to Dictionary<value,key>

    - by code4life
    I'm having a low-brainwave day... Does anyone know of a quick & elegant way to transform a Dictionary so that the key becomes the value and vice-versa? Example: var originalDictionary = new Dictionary<int, string>() { {1, "One"}, {2, "Two"}, {3, "Three"} }; becomes var newDictionary = new Dictionary<string, int>(); // contents: // { // {"One". 1}, {"Two". 2}, {"Three", 3} // };

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  • Problem in converting ToDictionary<Datetime,double>() using LINQ(C#3.0)

    - by Newbie
    I have written the below return (from p in returnObject.Portfolios.ToList() from childData in p.ChildData.ToList() from retuns in p.Returns.ToList() select new Dictionary<DateTime, double> () { p.EndDate, retuns.Value } ).ToDictionary<DateTime,double>(); Getting error No overload for method 'Add' takes '1' arguments Where I am making the mistake I am using C#3.0 Thanks

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  • LINQ extention SelectMany in 3.5 vs 4.0?

    - by Moberg
    Hi When I saw Darins suggestion here .. IEnumerable<Process> processes = new[] { "process1", "process2" } .SelectMany(Process.GetProcessesByName); ( http://stackoverflow.com/questions/3059667/process-getprocessesbyname/3059733#3059733 ) .. I was a bit intrigued and I tried it in VS2008 with .NET 3.5 - and it did not compiling unless I changed it to .. IEnumerable<Process> res = new string[] { "notepad", "firefox", "outlook" } .SelectMany(s => Process.GetProcessesByName(s)); Having read some Darins answers before I suspected that it was me that were the problem, and when I later got my hands on a VS2010 with.NET 4.0 - as expected - the original suggestion worked beautifully. My question is : What have happend from 3.5 to 4.0 that makes this (new syntax) possible? Is it the extentionmethods that have been extended(hmm) or new rules for lambda syntax or? I've tried to search but my google-fu was not strong enough. Please forgive if the question is a bit naive and note that I've taged it as beginner :)

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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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  • Assigining ID vs object - linq to sql

    - by jess
    Say, I have an entity Customer which has relationship with city,order etc.Now,when I am adding a customer object,should I assign customer.cityid, or customer.city? Now,from form I get cityid from dropdown,to assign city object,I will have to make a query using id selected.

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  • Does AsEnumerable() cache all result (LINQ)

    - by Akshay
    When we call a query operator on a sequence, a sequence-specific operator gets called. I mean if i call Where<>() operator on IEnumerable<>, the operator that will be called will be defined in Enumerable class and if it's called on IQueryable<>, the one defined in Queryable class will be called. Consider the operator Reverse, defined in the Enumerable class. If i want to call it on Iqueryable<> then I must use the AsEnumerable<>() operator to first convert it into IEnumerable<>. db.Countries.OrderBy(cntry=>cntry.CountryName).AsEnumerable().Reverse() But the Reverse operator got to have all records at the same time so that it can reverse them. In the above code do all the records get loaded in memory first and then the Reverse() operator is reversing it ?

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  • linq include with condition

    - by user276640
    i have function public Menu Details(int? id) { return _dataContext.Menu.Include("ChildMenu").FirstOrDefault(m => m.MenuId == id); } now i need to add condition to child list ChildMenu something like fieldname=id. how can i do it?

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  • Conditional Join In LINQ?

    - by Soo
    I am trying to write a query that grabs information from one database and joins it to information in a different database. TableA idA valueA idB TableB idB valueB The tricky part is that in TableA, idB isn't always defined, so when I do a normal join, I only get results where TableA has a idB value. What I want is to be able to grab all of the information from TableA even if it doesn't have a corresponding idB value.

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  • For-Loop and LINQ's deferred execution don't play well together

    - by Tim Schmelter
    The title suggests that i've already an idea what's going on, but i cannot explain it. I've tried to order a List<string[]> dynamically by each "column", beginning with the first and ending with the minimum Length of all arrays. So in this sample it is 2, because the last string[] has only two elements: List<string[]> someValues = new List<string[]>(); someValues.Add(new[] { "c", "3", "b" }); someValues.Add(new[] { "a", "1", "d" }); someValues.Add(new[] { "d", "4", "a" }); someValues.Add(new[] { "b", "2" }); Now i've tried to order all by the first and second column. I could do it statically in this way: someValues = someValues .OrderBy(t => t[0]) .ThenBy(t => t[1]) .ToList(); But if i don't know the number of "columns" i could use this loop(that's what I thought): int minDim = someValues.Min(t => t.GetLength(0)); // 2 IOrderedEnumerable<string[]> orderedValues = someValues.OrderBy(t => t[0]); for (int i = 1; i < minDim; i++) { orderedValues = orderedValues.ThenBy(t => t[i]); } someValues = orderedValues.ToList(); // IndexOutOfRangeException But that doesn't work, it fails with an IndexOutOfRangeException at the last line. The debugger tells me that i is 2 at that time, so the for-loop condition seems to be ignored, i is already == minDim. Why is that so?

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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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  • Strange LINQ to SQL Behavior

    - by mcass20
    What is wrong with the last query? Is it a bug or am I missing something? This query returns 2 records (correct): query = query.Where(Log => SqlMethods.Like(Log.FormattedMessage, "%<key>Name</key><value>David</value>%")); This query returns 2 records (correct): query = query.Where(Log => SqlMethods.Like(Log.FormattedMessage, "%<key>Name</key><value>%David%</value>%")); This query returns 0 records (correct): query = query.Where(Log => SqlMethods.Like(Log.FormattedMessage, "%<key>Name</key><value>av</value>%")); This query returns 2 records (correct): query = query.Where(Log => SqlMethods.Like(Log.FormattedMessage, "%<key>Name</key><value>%av%</value>%")); This query returns 0 records (correct): query = query.Where(Log => SqlMethods.Like(Log.FormattedMessage, "%<key>Name</key><value>v</value>%")); This query returns 15 records (incorrect, should return 2): query = query.Where(Log => SqlMethods.Like(Log.FormattedMessage, "%<key>Name</key><value>%v%</value>%"));

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  • LINQ, creating unique collection of a collection

    - by Wish
    I have class Vertex and a class Edge (Edge holds 2 properties - Vertex Source and Vertex Target); Edges and Vertexes are collected into lists Some example: A-->B // edge from vertex A to B B-->C // edge from vertex B to C C-->A // edge from vertex C to A A-->C // edge from vertex A to C -- this is two way edge So I would like to make IDictionary<Edge, bool> which would hold edges (A--B and B--A would be like 1), and bool - if it is two way or no. I need it because when I draw them now, it draws 2 arrows under one another. I would better make 1 arrow. So I'm pretty stuck right here... May anybody help me a bit ?

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  • Linq order by aggregate in the select { }

    - by Joe Pitz
    Here is one I am working on: var fStep = from insp in sq.Inspections where insp.TestTimeStamp > dStartTime && insp.TestTimeStamp < dEndTime && insp.Model == "EP" && insp.TestResults != "P" group insp by new { insp.TestResults, insp.FailStep } into grp select new { FailedCount = (grp.Key.TestResults == "F" ? grp.Count() : 0), CancelCount = (grp.Key.TestResults == "C" ? grp.Count() : 0), grp.Key.TestResults, grp.Key.FailStep, PercentFailed = Convert.ToDecimal(1.0 * grp.Count() /tcount*100) } ; I would like to orderby one or more of the fields in the select projection.

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  • Linq 2 SQL Grouping Question

    - by Jack Marchetti
    var groups = from p in dc.Pool join pm in dc.PoolMembers on p.ID equals pm.PoolID group p by p.Group into grp select new { grp.ID }; This isn't working. Basically I want to do the grouping, and then select certain columns, but when I do select new { grp. } I get no intellisense, so I'm obviously doing something wrong. Any ideas?

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  • Use of where in multiple joins to remove rows - linq

    - by bergin
    hi, I have a table of orders. the status is on the soilorders which is joined to the orders. I only want to return orders where the joined soilorder does not have status "Removed". I had thought that join sso in db.SoilSamplingOrders on ord.order_id equals sso.order_id where sso.status.Equals("Removed")!=true but then no records are returned! thanks for any help (query below) var query = from ord in db.Orders join sso in db.SoilSamplingOrders on ord.order_id equals sso.order_id where sso.status.Equals("Removed")!=true join cust in db.Customers on ord.customer_id equals cust.customer_id select new Listing { assigned_to = sso.assigned_to, company = cust.company, order_id = ord.order_id, order_created = ord.order_created, customer_id = ord.customer_id, order_created_by_employ_id = ord.order_created_by_employ_id, first_farm_on_order = (from f in db.SoilSamplingSubJobs where f.order_id == ord.order_id select new ListingSubJob { first_farm_on_order = f.farm }). AsEnumerable().First().first_farm_on_order, total_fields = (from f in db.SoilSamplingSubJobs where f.order_id == ord.order_id select new { f.sssj_id }).AsEnumerable().Count(), total_area = (float?) (from f in db.SoilSamplingSubJobs where f.order_id == ord.order_id && f.area_ha != null select f.area_ha ).Sum() ?? 0 , total_area_ph_density = (float?)(from f in db.SoilSamplingSubJobs where f.order_id == ord.order_id && f.ph != null select f.ph).Sum() ?? 0, };

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