linq

Expression Tree Binary Expression for an 'In' operation

I'm trying to build an expression tree (still) but getting further! I need to create a BinaryExpression to perform an 'In' comparison between a Member and a collection of items. Hence, the expression should return true if the member is contained within the items. This obviously does not exist: Expression.MakeBinary(ExpressionType.In, m...

LINQ Query to DataTable.DataSource

I am trying to perform a LINQ query on a DataTable and show the result in another DataTable. My source DataTable looks something like this: DataTable myDataTable = new DataTable(); myDataTable.Columns.Add("OrderID", typeof(int)); myDataTable.Columns.Add("Date", typeof(DateTime)); myDataTable.Columns.Add("UnitsPurchased", typeof(int)); ...

Traverse list to add elements using .NET

I have a list of objects. Each object has an integer quantity and a DateTime variable which contains a month and year value. I'd like to traverse the list and pad the list by adding missing months (with quantity 0) so that all consecutive months are represented in the list. What would be the best way to accomplish this? Example: Origina...

Linq, double left join and double count

Hi! I'm looking to translate this SQL statement to a well working & performant LINQ command. I've managed to have the first count working using the grouping count and key members, but don't know how to get the second count. select main.title, count(details.id) as details, count(messages.id) as messages from main left outer join detail...

How can I do more than one level of cascading deletes in Linq?

If I have a Customers table linked to an Orders table, and I want to delete a customer and its corresponding orders, then I can do: dataContext.Orders.DeleteAllOnSubmit(customer.Orders); dataContext.Customers.DeleteOnSubmit(customer); ...which is great. However, what if I also have an OrderItems table, and I want to delete the order i...

XElement Path Validation

Hello, I am trying to validate Elements and Attributes exist in an XElement. Basically, I was wondering if anyone had a generic way to check if a give path is null. I don't have access to System.Xml.XPath (doing this for compact framework). Basically what I have is: <root value"1000"> <element1>test<element1> <element2>1<element...

Can I use Linq to project a new typed datarow?

I currently have a csv file that I'm parsing with an example from here: http://alexreg.wordpress.com/2009/05/03/strongly-typed-csv-reader-in-c/ I then want to loop the records and insert them using a typed dataset xsd to an Oracle database. It's not that difficult, something like: foreach (var csvItem in csvfile) { DataSet.MYTABLED...

Linq Query Giving Error

I am getting this error when I use the Linq expression of var emp = _testModel.Where(m => m.Date == DateTime.Now).Select(m=>m); The error is 'System.Collections.Generic.IEnumerable<TestModel>' does not contain a definition for 'System' and no extension method 'System' accepting a first argument of type 'System.Collections.Generic.IE...

ADO.NET Entity Model and LINQ

Hi all I'm using an ADO.NET Entity Model which I'm trying to query using LINQ. The problem I'm having is that I can't specify the where clause as I'd like. For instance, consider the following query: AccountsDM db = new AccountsDM(ConfigurationManager.ConnectionStrings["PrimaryEF"].ConnectionString); var accounts = from a in db.Accoun...

How can I transform a DataTable in a group-by date DataTable with LINQ?

I have a untyped DataTable that looks like this (srcTbl): date col_1 col_2 ... col_n 1.3.2010 00:00 12.5 0 ... 100 1.3.2010 01:00 0 0 ... 100 1.3.2010 22:00 0 0 ... 100 1.3.2010 23:00 12.5 0 ... 100 ... 31.3.2010 00:00 2 0 ... 100 31.3.2010 01:00 2 0 ... 2...

Check if XML-node has attribute with Linq C#?

How can I check and see if a node actually has a certain attribute? I have an XML-file containing several nodes looking like this: <Field From="OldString" To="NewString" /> So far so good. The problem is that this structure is about to be changed to that some nodes will look like this: <Field From="OldString" To="NewString" PrefixVa...

Compiled Linq & String.Contains

i'm using linq-to-sql and i'm use complied linq for better performance. I have a users table with a INT field called "LookingFor" that can have the following values.1,2,3,12,123,13,23. I wrote a query to return the users based on the "lookingFor" column i want to return all users that contains the "lookingFor" value (not only those eq...

Avoiding Redundancies in XML documents

I was working with a certain XML where there were no redundancies <person> <eye> <eye_info> <eye_color> blue </eye_color> </eye_info> </eye> <hair> <hair_info> <hair_color> blue </hair_color> </hair_info> </hair> </person> As you can see, the sub-tag eye-color makes ref...

Unable to update the EntitySet 'ItemRankList' because it has a DefiningQuery and no <UpdateFunction> element exists in the <ModificationFunctionMapping> element to support the current operation.

Any ideas why does the entity framework in LINQ gives following strange error: "Unable to update the EntitySet 'ItemRankList' because it has a DefiningQuery and no element exists in the element to support the current operation." ...

LinqToSQL: Not possible to update PrimaryKey?

I have a simple table (lets call it Table1) that has a NVARCHAR field as the PK. Table1 has no association with any other tables. When I update Table1's PK column using LinqToSQL it fails. If I update other column it succeeds. I could delete this row and insert new one in Table1, but I don't want to. There is a transaction table which ...

LINQ query - null date

Hi Ive a simple linq query to return records with a null date field, just want to check the synatx of the "where" line is ok var query2 = from cs in db.tblCases where cs.date_closed == null etc, etc, thanks again DD ...

How can I filter a list of objects using lambda expression?

I know I shouldn't have id's with the same value. This is just fictitious, so overlook that. I have: List<Car> carList = new List<Car>(); carList.Add(new Car() { id = 1, name = "Honda" }); carList.Add(new Car() { id = 2, name = "Toyota" }); carList.Add(new Car() { id = 1, name = "Nissan" }); I want to use Lambda Expression to retriev...

Group by and order by

using LINQ to NHibernate does anybody know how to use group by and order by in the same expression. I am having to execute the group by into a list and then order this, seem that I am missing soemthing here ??? Example:- Private function LoadStats(...) ... Dim StatRepos As DataAccess.StatsExtraction_vwRepository = New DataAccess.Sta...

In C# is there a function that correlates sequential values on a IEnumerable

Hi all, I have a IEnumerable. I have a custom Interval class which just has two DateTimes inside it. I want to convert the IEnumerable to IEnumerable where n DateTimes would enumerate to n-1 Intervals. So if I had 1st Jan, 1st Feb and 1st Mar as the DateTime then I want two intervals out, 1st Jan/1st Feb and 1st Feb/1st March. Is th...

How To Join Tables from Two Different Contexts with LINQ2SQL?

I have 2 data contexts in my application (different databases) and need to be able to query a table in context A with a right join on a table in context B. How do I go about doing this in LINQ2SQL? Why?: We are using a SaaS product for tracking our time, projects, etc. and would like to send new service requests to this product to p...