DotNetKicks.com - published linq stories

String Matching in LINQ

Tue, 24 Apr 2012 13:27:58 GMT

Performing simple string equality tests is often not enough when application user convenience is key. Often only a fragment of a string is known to the user, or many of them. Sometimes there is a need to search for a fragment in multiple columns. Which options does OpenAccess and LINQ provide to perform string matching? Into which SQL is the LINQ expression translated?

Difference between SkipWhile and Where in linq

Tue, 17 Apr 2012 13:41:40 GMT

Before some time I have written a blog post about the SkipWhile operator and a reader of my blog asked me that we can do the same thing with Where also but there is a difference between this two. So In this post I am going to explain you difference between those two. Where operator filters a list of collection based on condition. It will filter whole collection while SkipWhile will only skip those elements in list until condition is true and after that it will stop filtering of skipping. Now let's take an example where we can see the difference between Where and SkipWhile. Following is a code for that.

SkipWhile Method in Linq

Mon, 16 Apr 2012 09:59:10 GMT

I have been playing around linq and I have found great method call SkipWhile method. SkipWhile methods skips particular element which matches condition in predicate this can be use full in condition where we need to skip elements on particular condition. So let's take some example. I have written following console application code.

TakeWhile operator in linq

Mon, 16 Apr 2012 09:59:10 GMT

In this post I am going to explain TakeWhile Operator in details. TakeWhile is one of partitioning operator available in Linq. It will take sequence until condition becomes false.

LOLCode Parser

Wed, 21 Mar 2012 23:37:06 GMT

LOLCode parser and compiler. Now your cat can code for you.

Add a visual Linq expression builder to your app today!

Fri, 03 Feb 2012 23:44:34 GMT

Rabb Moshe Plotkin has created and open-sourced a control for creating Linq queries visually. Using this control, you can give your users the power to query data, rather than writing canned reports or queries.

A Generic Equality Comparer for LINQ

Tue, 17 Jan 2012 14:26:20 GMT

LINQ operators generally use lambda expressions to control their processing and output. Some operators use IEqualityComparer<T> implementations to compare values. This article describes a generic comparer, driven by delegates, designed for use in queries.

Monadic Philosophy Part 2 - The LINQ Monad

Fri, 06 Jan 2012 14:40:27 GMT

If you don't come from a math or philosophy background (and I don't) "monad" sounds like a made-up word. Of course, understanding OO's use of terms like "class" and "object" can be hard to grok at first too. But at least those terms have some grounding in real-world concepts that non-math geeks come across. Because I couldn't draw an analogy of monads to anything at first, it made grasping the concept of monads very hard for me.

Seeing the SQL Generated by LINQ to Entity Queries -- Visual Studio Ma

Mon, 12 Dec 2011 16:03:46 GMT

Sometimes you really, really, really want to see the SQL that LINQ generates when working with the Entity Framework. There is a really simple way to do this using the immediate window that does not involve installing a profiler.

Architecting Your Data Access Layer with the Entity Framework

Sat, 03 Dec 2011 03:32:25 GMT

I had the pleasure to co-present with one of my fellow evangelists, Dave Bost, on architecting and developing with the ADO.NET Entity Framework this week. I focused on application architecture topics while Dave focused on developing applications.

NHibernate.Linq Pitfalls: Casting

Mon, 31 Oct 2011 15:31:32 GMT

One thing that needs to be always remembered when writing NHibernate.Linq queries is that it is going to be translated into SQL eventually. What this means is that we can't do everything in our Select or Where conditions - we are restricted by the capabilities of underlying database and SQL language itself.

Dynamic Lambda Expression For Sorting A List / Collection Using Comple

Thu, 25 Aug 2011 20:57:53 GMT

In my previous post we discussed on sorting the list / collection using dynamic lambda expression for properties. In this article we will see how to sort on complex properties. So what is a complex property. Consider the class diagram as shown below In our scenario, we have "Employee" entity, where we have a property "Department" which is a complex type. Now let us assume that we are binding the list of employees list along with the department name, then we will have to use item template along with "Bind" method called.

Dynamic OrderBy using LINQ to SQL

Wed, 24 Aug 2011 20:33:21 GMT

Dynamically ordering your data when using LINQ to SQL as a backend

LINQ - Comparing Count() to Any()

Sun, 21 Aug 2011 15:36:55 GMT

Compares the performance differences and considerations between using Count and Any to determine if any elements in a collection match a filter. A commenter also points out that using Any with an embedded filter gives different performance results as well. While it's important not to prematurely optimize, it is important to consider the points in this article if you write queries like this that run in a tight loop or iterate over large sets of data.

Paging in LINQ

Sat, 06 Aug 2011 01:43:25 GMT

Implementation paging in LINQ

Samples for Parallel Programming with the .NET Framework

Sun, 31 Jul 2011 23:23:26 GMT

The .NET Framework 4 comes with several new features for writing parallel and concurrent applications, including Parallel LINQ (PLINQ), the Task Parallel Library (TPL), new thread-safe collections, and plenty of new coordination and synchronization data structures. This sample includes example applications and library functionality that demonstrate this support.

Interactive Extensions for LINQ to Objects

Sun, 31 Jul 2011 19:31:17 GMT

Based on the work done in Reactive Extensions (Rx), a set of additional LINQ to Objects query operators are available as Interactive Extensions(Ix). Missing features can be found in a set of IEnumerable extension methods under the System.Linq namespace by looking under the API.

Does LINQ to SQL eliminate the possibility of SQL Injection

Fri, 29 Jul 2011 03:53:12 GMT

By default, LINQ to SQL uses parameterized queries rather than concatenated strings when executing your LINQ queries. As a result, if a user tries to perform SQL Injection by improperly escaping parts of the SQL, the escape is considered part of the parameter rather than part of the query and thus avoids the injection. However, as we discussed in chapter 8 of LINQ in Action, LINQ to SQL greatly reduces the possibility of SQL Injection, but doesn't completely eliminate it. For example, if you are using ...

LINQ Pad vs. Visual Studio for Learning LINQ

Tue, 26 Jul 2011 01:51:28 GMT

LINQPad is a resourceful tool when working with or learning LINQ. Translating from LINQPad to Visual Studio is essential since most programming occurs here. In this article a LINQ query is examined in LINQPad and then migrated to Visual Studio. Other LINQ examples are provided as well.

LINQ ToLookup Operator

Mon, 23 May 2011 06:25:33 GMT

Language-Integrated Query (LINQ) provides several methods that allow a sequence to be manipulated, filtered and grouped. ToLookup performs a grouping operation that results in a sequence of key / value pairs, where each value is another sequence.

The Power of LINQ - Sorting Lists with a single line of code

Fri, 22 Apr 2011 07:03:55 GMT

This post, just like the code example, is short and to the point, because that's how LINQ is - short, to the point, and powerful.

O/R Mapping domain query optimizations

Mon, 04 Apr 2011 08:11:07 GMT

Executing domain logic in DB

How to find Duplicates Elements with LINQ-CodeGain

Mon, 04 Apr 2011 08:10:32 GMT

In this snippet I am going to discuss about how to get list of duplicate items for the collection that we do in sql.

SQL Server XQuery with LINQ To SQL

Wed, 16 Mar 2011 06:31:10 GMT

LINQ To SQL doesn't provide a way to include Xquery expressions in queries. The simplest solution is to create SQL user-defined functions that perform the Xquery for you and return scalar results. This works pretty well for small databases, but you lose the benefit of SQL Server's XML indexes. To get around that, we can modify the SQL command text to expand the function calls into raw Xquery expressions.

Modifying LINQ To SQL command text

Sun, 13 Mar 2011 20:37:17 GMT

Here's a bit of code that'll let you modify any command text LINQ To SQL generates before it hits the database. It's always been possible to call DataContext.GetCommand and use modified SQL in a call to DataContext.Translate or DataContext.ExecuteQuery, but that's pretty restrictive in the complexity of query you can use. Also, if LINQ To SQL decides it needs to batch multiple SELECT statements for the desired results, GetCommand can only give you the first one. The first thing to do is replace the IProvider implementation used by your DataContext. Unfortunately, DataContext's Provider property is both private and read-only. Also, the IProvider interface itself is private. This is bad in every way, and we absolutely shouldn't try to hack our way through that. but we will.