After much Google searching and code experimentation, I'm stumped on a complex C# LINQ-to-objects problem which in SQL would be easy to solve with a pair of ROW_NUMBER()...PARTITION BY functions and a subquery or two. Here's, in words, what I'm trying to do in code-- the underlying requirement is removing duplicate documents from a lis...
I have a class like this: class MyClass<T> { public string value1 { get; set; } public T objT { get; set; } } and a list of this class. I would like to use .net 3.5 lambda or linq to get a list of MyClass by distinct value1. I guess this is possible and much simpler than the way in .net 2.0 to cache a list like this: List<MyC...
Hi, I want to define stored procedure parameters which do not allow null arguments. That @MailItemId int OUTPUT will be not nullable because when I import the stored procedure into the LINQ to SQL designer it says @MailIetmid is ref int? mailItemId. Thanks. ...
I've got a query in C# that is working for me to query the metadata for the Entity Framework. I need to convert it to VB.NET, but I'm struggling to convert the AS keyword to "cast" meta to System.Data.Metadata.Edm.EntityType. I've tried TryCast, CType, Cast, etc. Here's the query in C#: var queryResult = from meta in oc.MetadataWorks...
Hello, i have a problem with my linq to xml query var q = (from f in xmlLang.Element("lang").Elements("page") where (string)f.Attribute("id") == "home" select f.Element(LangElement).Value.ToString()).Take(1).SingleOrDefault(); The xml looks like this, <lang> <page id="home"> <hello>Hello!</hello>...
I am trying to come up with a linq query to convert an IEnumerable<int> to another IEnumerable<int>, where each int in the result is the sum of all the ints up to that position from the initial list: Given int[] a I need int[] b Where b[0] = a[0], b[1] = a[0] + a[1], b[2] = a[0] + a[1] + a[2] and so on Alternatively, the sums above can...
Given a simple inheritance hierarchy: Person -> Student, Teacher, Staff Say I have a list of Persons, L. In that list are some Students, Teachers, and Staff. Using LINQ and C#, is there a way I could write a method that could retrieve only a particular type of person? I know I can do something like: var peopleIWant = L.OfType< Teache...
Are simple LINQ queries on an IEnumerable<T> lightweight or heavyweight? How do they compare to writing for or foreach loops by hand? Is there a general guideline for when to prefer LINQ versus manual searching? For example: var lowNums = from n in numbers where n < 5 select n; Compared to: List<int> lowNums = new List<i...
Now I come a stage to get all my data as a list in cache(objects) and my next thing I have to do is to remove some instances from the list. Normally, I would do removing like this: List<T> list; List<T2> toBeRemovedItems; // populate two lists foreach(T2 item in toBeRemovedItems) { list.Remove(delegate(T one) { // build a condit...
Hi All, I have Dynamic dataWebsite which uses a SQL SP to do update operations..I have a problem here, my delete functionality is also a update(setting IsDeleted=1) operations. I am currently using LINQ query and calling datacontext.SubmitChanges() for deleting. The problem is, the update LINQ query(that sets IsDeleted=1) when i call Su...
How to get list of tables (objects) from Entity framework model (edmx)? In LinqToSQL model, it's easy context.Mapping.GetTables(), but how in EF.. ...
AddOptional<tblObject>(x =>x.Title, objectToSend.SupplementaryData); private static void AddOptional<TType>(Expression<Func<TType,string>> expr, Dictionary<string, string> dictionary) { string propertyName; string propertyValue; Expression expression = (Expression)expr; while (expression.NodeType == ExpressionType.Lambd...
Hi i have a linq query below var Free = (from row in dt.AsEnumerable() where row.Field("AppointmentType") == "FreeTime" select new{ row.Field("BookedDate") row.Field("TravelTime")}).Min() what i want to do is have a minimum on the travelT...
I'm trying to query the unique reference number of a table using Linq to Entities. The ID is provided via a textbox and hence a string in my code. Obviously in the database table the field is an integer so I have tried using .ToString first and then .Contains in the same way you would with a varchar(). This doesn't seem to work, with the...
hello, I have web application where Iam using linq to business entites i have business data model. the problem is : I have table with one column that it dosen't allow null value, when I try to update this table the folloeing error arise: error The property 'e.g Carrier' is part of the object's key information and cannot be modified w...
I need to set my connection string for Linq to Sql based on an environment variable. I have a function which will return the connection string from the web.config based on the environment variable, but how do I get Linq to always use this "dynamically created" connection string (preferably without having to specify it every time)? I kn...
I have a Linq query that I copy to a DataTable which is then used to populate a gridview. I am using a group by "key" and "count" which I evaluate in the aspx page for a master/detail gridview with a repeater. The problem that I am encountering is that the gridview datasource and bind to the datatable is not presenting me with any addi...
I am trying to write a query that will search for "orders" that contain a certain "product" and I'm having a little difficulty getting it to work. Basically, this is what I'm trying to do: Dim orders = From o in db.Orders _ Where o.OrderProducts.Contains(Function(p) p.ProductID = 123) _ Select o I've also tr...
If I'm extending OnCreated for a LINQ to SQL table object, is it possible to get a reference to the data context to which the table belongs? For example, if I add a property to the data context: Partial Class MyDataContext Private _myValue As String Public ReadOnly Property MyValue As String Get Return _myValu...
While I'm pretty certain that the keys are unordered when returned from linq's ToLookup method, Is the order of values preserved? I can't find any documentation that says one way or the other. ...