I used the LINQ to SQL designer in Visual Studio to create an object model of a database. Now, I want to add XML comments to each generated property but I can't figure out how to do it without erasing the properties the next time the dbml file is refreshed. How can this be done? ...
I have a List<int> and a List<customObject>. The customObject class has an ID property. How can I get a List<customObject> containing only the objects where the ID property is in the List<int> using LINQ? Edit: I accepted Konrads answer because it is easier/more intuitive to read. ...
When designing LINQ classes using the LINQ to SQL designer I've sometimes needed to reorder the classes for the purposes of having the resultant columns in a DataGridView appear in a different order. Unfortunately this seems to be exceedingly difficult; you need to cut and paste properties about, or delete them and re-insert them manuall...
How can i update an entity that is disconnected from database? Code below does not run correctly and throws InvalidOperationExcepiton. public void Foo() { DataContext context = new DataContext(); LinqEntity item = new LinqEntity(){ Id = 1, Name = "John", Surname = "Doe"} ; context.LinqEntities.Attach(item, true); } ...
I have a List of Foo. Foo has a string property named Bar. I'd like to use linq to get a string[] of distinct values for Foo.Bar in List of Foo. How can I do this? ...
I found an example in the VS2008 Examples for Dynamic LINQ that allows you to use a sql-like string (e.g. OrderBy("Name, Age DESC")) for ordering. Unfortunately, the method included only works on IQueryable<T>. Is there any way to get this functionality on IEnumerable<T>? ...
What's the "best" (taking both speed and readability into account) way to determine if a list is empty? Even if the list is of type IEnumerable<T> and doesn't have a Count property. Right now I'm tossing up between this: if (myList.Count() == 0) { ... } and this: if (!myList.Any()) { ... } My guess is that the second option is fas...
This question is addressed to a degree in this question on LINQ to SQL .dbml best practices, but I am not sure how to add to a question. One of our applications uses LINQ to SQL and we have currently have one .dbml file for the entire database which is becoming difficult to manage. We are looking at refactoring it a bit into separate f...
There are numerous libraries providing Linq capabilities to C# code interacting with a MySql database. Which one of them is the most stable and usable on Mono? Background (mostly irrelevant): I have a simple C# (.Net 2.0) program updating values in a MySql database. It is executed nightly via a cron job and runs on a Pentium 3 450Mhz, L...
I've written this very simple function to replace a file extension using LINQ in C#.NET 3.5 however I have a feeling that there's a more elegant way to do this. (I'm not committed to using LINQ here - just looking for a more elegant approach.) Ideas? private string ReplaceFileExtension(string fileName, string newExtension) { ...
I'm trying to get the following bit of code to work in LINQPad but am unable to index into a var. Anybody know how to index into a var in LINQ? string[] sa = {"one", "two", "three"}; sa[1].Dump(); var va = sa.Select( (a,i) => new {Line = a, Index = i}); va[1].Dump(); // Cannot apply indexing with [] to an expression of type 'System.Col...
When executing SubmitChanges to the DataContext after updating a couple properties with a LINQ to SQL connection (against SQL Server Compact Edition) I get a "Row not found or changed." ChangeConflictException. var ctx = new Data.MobileServerDataDataContext(Common.DatabasePath); var deviceSessionRecord = ctx.Sessions.First(sess => sess....
How do you rewrite this in Linq? SELECT Id, Name FROM TableA WHERE TableA.Id IN (SELECT xx from TableB INNER JOIN Table C....) So in plain english, I want to select Id and Name from TableA where TableA's Id is in a result set from a second query. ...
I have an object graph serialized to xaml. A rough sample of what it looks like is: <MyObject xmlns.... > <MyObject.TheCollection> <PolymorphicObjectOne .../> <HiImPolymorphic ... /> </MyObject.TheCollection> </MyObject> I want to use Linq to XML in order to extract the serialized objects within the TheCollect...
I'm trying to find the correct names for these 2 "types" of coding expressions in LINQ so that I can refer to them correctly. I want to say that the first is called "Fluent Style"? var selectVar = arrayVar.Select( (a,i) => new { Line = a }); var selectVar = from s in arrayVar select new { Line = s }; ...
I have a list of Foo. Foo has properties Bar and Lum. Some Foos have identical values for Bar. How can I use lambda/linq to group my Foos by Bar so I can iterate over each grouping's Lums? ...
I have a collection of objects to which I'd like to just add a new property. How do I do that with LINQ? ...
Part of the web application I'm working on is an area displaying messages from management to 1...n users. I have a DataAccess project that contains the LINQ to SQL classes, and a website project that is the UI. My database looks like this: User -> MessageDetail <- Message <- MessageCategory MessageDetail is a join table that also conta...
I have just finished reading "LINQ in Action" which I have found to be a great resource. What are some other resources available? ...
Being relatively new to the .net game, I was wondering, has anyone had any experience of the pros / cons between the use of LINQ and what could be considered more traditional methods working with lists / collections? For a specific example of a project I'm working on : a list of unique id / name pairs are being retrieved from a remote...