linq

Linq causes collection to disappear when trying to use OrderByDescending

For background, I am using MongoDB and Rob Conery's linq driver. The code I am attempting is thus: using (var session = new Session<ContentItem>()) { var contentCollection = session.QueryCollection.Where(x => x.CreatedOn < DateTime.Now).OrderByDescending(y => y.CreatedOn).ToList(); ViewData.Model = contentCollection; } this wi...

Use LINQ to insert data from dataset to SQL

Let's say I have a dataset in an ASP.NET website (.NET 3.5) with 5 tables, each has roughly 30,000 rows and an average of 12 columns. I want to insert all of the data from the dataset into 5 very-similar-but-not-quite-identical tables in SQL Server 2008. I also want to use LINQ (personal preference - trying to learn something new). Is...

LINQ - How to query a range of effective dates that only has start dates

I'm using C# 3.5 and EntityFramework. I have a list of items in the database that contain interest rates. Unfortunately this list only contains the Effective Start Date. I need to query this list for all items within a range. However, I can't see a way to do this without querying the database twice. (Although I'm wondering if delay...

Converting SQL to LINQ to XML

I'm writing the following code to convert SQL to LINQ and then to XML: SqlConnection thisConnection = new SqlConnection(@"Data Source=3BDALLAH-PC;Initial Catalog=XMLC;Integrated Security=True;Pooling=False;"); thisConnection.Open(); XElement eventsGive = new XElement("data", from c in ?????? select new XElement("ev...

Reading/Writing DataTables to and from an OleDb Database LINQ

My current project is to take information from an OleDbDatabase and .CSV files and place it all into a larger OleDbDatabase. I have currently read in all the information I need from both .CSV files, and the OleDbDatabase into DataTables.... Where it is getting hairy is writing all of the information back to another OleDbDatabase. Right...

C# Linq List Contains Similar Elements

Hi All, I am looking for linq query to see if there exists a similar object I have an object graph as follows Cart myCart = new Cart { List<CartProduct> myCartProduct = new List<CartProduct> { CartProduct cartProduct1 = new CartProduct { List<CartProductAttribute> a = new List<CartProductAttribute> ...

LINQ group by and getting latest value

Say I have a structure like: class SomeObject Public Name as String Public Created as Date ... end class I have a List(of SomeObject), which has multiple entries for each name with different times. I'd like to select the newest (largest Created value) object for each Name. Given: Name Created A 2010-04-16 * A ...

How to use LINQ To Entities for filtering when many methods are not supported?

Hi, I have a table in SQL database: ID Data Value 1 1 0.1 1 2 0.4 2 10 0.3 2 11 0.2 3 10 0.5 3 11 0.6 For each unique value in Data, I want to filter out the row with the largest ID. For example: In the table above, I want to filter out the third and fourth row because the fifth and sixth rows...

Cast MyEntity To LinqEntity throw a base controller class

hi there i design a multilayer we appliction andusing LINQ a my data provider i need to user my own Entites instead o LINQ etities. so i created Entities Project and create my entities in it. when i get data from contex and cast them to my entities , everything is ok. but when i want to cast on of my entities to linq entity , an excepti...

Challenge: Neater way of currying or partially applying C#4's string.Join

Background I recently read that .NET 4's System.String class has a new overload of the Join method. This new overload takes a separator, and an IEnumerable<T> which allows arbitrary collections to be joined into a single string without the need to convert to an intermediate string array. Cool! That means I can now do this: var evenNum...

How to pronounce LINQ

I've always pronounce it like "link", but I also heard people pronounce it "Lin-Q". I am really curious whcih one is correct. ...

Automatic .NET code, nhibernate session, and LINQ datacontext clean-up?

Hi all, in my goal to adopt better coding practices I have a few questions in general about automatic handling of code. I have heard different answers both from online and talking with other developers/programmers at my work. I am not sure if I should have split them into 3 questions, but they all seem sort of related: 1) How does .NET ...

How to build a LINQ query from text at runtime?

I have a class A { public int X; public double Y; public string Z; // and more fields/properties ... }; and a List<A> data and can build a linq query like e.g. var q = from a in data where a.X > 20 select new {a.Y, a.Z}; Then dataGridView1.DataSource = q.ToList(); displays the selection in my DataGridView. Now the que...

A better solution than element.Elements("Whatever").First()?

I have an XML file like this: <SiteConfig> <Sites> <Site Identifier="a" /> <Site Identifier="b" /> <Site Identifier="c" /> </Sites> </SiteConfig> The file is user-editable, so I want to provide reasonable error message in case I can't properly parse it. I could probably write a .xsd for it, but that seems kind of overk...

How to do a STAR search in LINQ

I'm not sure about clarity of the STAR word. I'm implementing a search method using linq-to-object in c#. And I want to do a search with * (star) operator like most of search apps or web can do. e.g. If I typed "p*", results should be everything starting with "p". And it should work for prefix star, suffix star or star in the middle. ...

Linq Datagrid Source Link Each Row

Okay I do not even know where to begin when it comes to this I am continuing from this question: http://stackoverflow.com/questions/2664029/linq-to-sql-statement-issue Where I searched multiple columns in a table and returned my values in a datagrid, Ive done basic formatting on the grid but am unable to decipher how I would go about ge...

Difference between Expression<Func<>> and Func<>

As an example, why do most LINQ operators accept Expression<Func<TSource>> and it's equivalent Func<TSource> What's the benefit/reason for using the generic Expression class instead of straight up lamda syntax? ...

LINQ to SQL does not update when data has changed in database

I have this problem where after a field (say Field3 in table MyTable) is updated on the database, MyTable.Field3 (in C#) is still returning the old value. I suspect there is some caching...? How do I force it to: Read the value from the database? OR Update the value in the MyTable class? Or is there anything I miss? I am new to LINQ ...

Serialization mode in LINQ to SQL

what is means of serailzation mode in LINQ to SQL? what architecture does LINQ to SQL uses internally (connected or disconnected architecture)? ...

How do I use "Into" LINQ expression in VB.NET?

I'm converting from C# this LINQ expression. However, it does not seem to work. C# return (from w in fishSticks group w by w.FishQty into g orderby g.Key descending select g).First().First(); VB Return (From w In fishSticks Group w By w.FishQty Into g() Order By g.Key Descending Se...