SPS 2010: LINQ to SharePoint - What CAML lies behind my query?

Author: Tobias Zimmergren
http://www.zimmergren.net | http://www.tozit.com | @zimmergren

Introduction

The two following questions are quite popular in my SharePoint 2010 developer training classes, so I ought to answer them right here.

"What does LINQ to SharePoint really do?"
"Can I see the CAML query generated by the LINQ to SharePoint query?"

The answer is simple: Yes, you can see the results of your generated LINQ query by using the Log property of your DataContext object.

What CAML lied behind my LINQ to SharePoint query?

In order to fetch the CAML query that lies behind your LINQ query, all you need is to work with the .Log object of your DataContext.

See this simple example, which simply outputs the CAML query to an XML-file for easy reading:

This will essentially generate the following content in the file C:\MyEntitiesDataContextQuery.xml:

As you can see, the LINQ to SharePoint query is automatically turned into a CAML Query.

Summary

Yep, all you need is the .Log property to fetch the CAML query from your LINQ statement. In my sample I'm outputting it to a file called C:\MyEntitiesDataContextQuery.xml.

You could of course output it in any other way you want - not just a physical file on the file system. The Log property is of the type TextWriter.

Enjoy!

Published: Feb-19-10 | 7 Comments | 0 Links to this post

SPS 2010: Getting started with LINQ to SharePoint in SharePoint 2010

Author: Tobias Zimmergren
http://www.zimmergren.net | http://www.tozit.com | @zimmergren

Introduction

In SharePoint 2010 you now have the ability to use LINQ syntax to fetch items from your lists instead of using the "traditional" approach of CAML queries. (Including SPSiteDataQuery and SPQuery objects)

In this article I will give you a brief introduction to how you can get started using LINQ queries in SharePoint, also known as LINQ to SharePoint.

Basics of LINQ?

As a prerequisite to this article, I'm going to imply that you know what LINQ is and how to write basic LINQ queries in any .NET application already. I'm not going to dive into the details about LINQ or the syntax itself here - please see MSDN for that!

LINQ to SharePoint!

In order to work with LINQ in SharePoint 2010, we need use a tool called SPMetal.exe which resides in the 14\bin folder. This tool is used to generate some entity classes which Visual Studio 2010 can use to get IntelliSense, and allows for LINQ-based queries to be performed on your lists.

Noteworthy:

LINQ to SharePoint queries are translated to proper CAML queries
CAML queries are in turn later translated to SQL queries

SPMetal.exe

Using the tool called SPMetal, we generate our entity-classes that are needed to perform these object oriented queries toward our SharePoint server.

These are the required steps to get hooked up:

Launch a cmd-window and navigate to C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\bin
Run the following command to utilize the SPMetal.exe tool with the following syntax:

SPMetal.exe /web:http://yoursite /code:C:\YourEntityFile.cs
Example:

Now navigate to C:\ (or wherever you chose to output your file) and make sure the file has been generated:
Open up the file and take a look at the content that SPMetal now have provided us with:

Note that the class name is now MyEntitiesDataContext. It's based on the name you specify as your code file in the SPMetal.exe command line tool.

If you were to use /code:C:\Awesome.cs instead, it would generate a class called AwesomeDataContext.

With that done - all we need to do is import it to one of our projects and use it!

Visual Studio 2010 - Let's create a sample Web Part that utilizes LINQ to SharePoint

In this sample I will create a simple Web Part that will use LINQ to SharePoint syntax to fetch some information from the Announcements list. A basic sample I use in my training classes as well, and should be fairly easy to grasp!

Create a new project (I'm going to create a new Visual Web Part project)
Import your DataContext-file by choosing your Project -> Add -> Existing Item:
Specify your file (mine is called MyEntities.cs):
Make sure it's properly placed in your project structure - then we're good to go:

Alright - that's easy enough. Thus far we have created an entity file using SPMetal.exe and now we have successfully imported it into our project.

Add proper references

Now in order to use LINQ to SharePoint, you also need to reference the Microsoft.SharePoint.Linq assembly. Point to references, right-click and choose "Add Reference" and select the Microsoft.SharePoint.Linq.dll file:

In your code, reference the assemblies:

Ready to code?

What you should've done up until now is this:

Generate your entities using the SPMetal.exe tool
Reference the newly created file from your SharePoint project
Make sure you're using the proper references for System.Linq and Microsoft.SharePoint.Linq
Be ready to code :-)

Code!

In my example I will have a Visual Web Part that will use LINQ to SharePoint to fetch all Announcements from my Announcement-list and work with those results. If you want to see the entire project, look at the bottom of this article where you can download it.

IntelliSense!

While you code your queries using LINQ to SharePoint, you will now have access to IntelliSense, which you did not have with CAML queries:

I'm going to leave it at that - very (very) easy to get started with LINQ to SharePoint, and all you really need to know is to start using the SPMetal tool to generate your entity classes and hook'em up with Visual Studio to start coding.

Summary & Download

As you can see, there's not a lot of things you need to do in order to work with LINQ in your SharePoint applications with your SharePoint-data.

I've been pinged plenty of times on how you can get started with this, and there you have it. More in-depth articles to come later - this is just to get your wagon rolling!

To download the sample project, click here: [Download]

Enjoy!

Published: Feb-19-10 | 4 Comments | 0 Links to this post

How to: LINQ with SharePoint - .NET 3.5 Framework with SharePoint Part 2

Author:	Tobias Zimmergren
Blog:	http://www.zimmergren.net

Introduction

In my previous article title "How to: Get up and running with .NET 3.5 in your SharePoint environment" I talked about how you can manually set up your SharePoint environment for use with Microsoft .NET Framework 3.5.

In this article I will talk about how you can incorporade some of the technologies used in .NET 3.5 to query a SharePoint list. More precisely, I will talk about how you easily can use LINQ from the .NET 3.5 framework to get started with .NET 3.5 in SharePoint.

A more in-depth article might be posted later, but this one is simply providing simple code instructions to what a Web Part that utilizes LINQ can look like!

Prerequisites

In order to follow along with this walkthrough, you should have the following bulletpoints checked:

.NET Framework 3.5 is installed
You've configured your SharePoint environment for use with .NET 3.5
- See this article for more information and help on this issue: How to: Get up and running with .NET 3.5 in your SharePoint environment

Creating a custom Web Part which utilizes .NET 3.5 in SharePoint

The code below will give you the heads up on how to fetch the SPListItem objects from an SPList object and sort them alphabetically. You can of course use the 'where'-clause with LINQ aswell to filter out which objects (SPListItem objects) to fetch from the SPList.

Example task list to fetch the data from:

Using the following code, I've used LINQ to retreive all the list items and sort them ascending by title!

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.SharePoint;

namespace Zimmergren.net35.LINQWebPartSample
{
    public class SPLINQ : System.Web.UI.WebControls.WebParts.WebPart
    {
        protected override void Render(System.Web.UI.HtmlTextWriter writer)
        {
            base.Render(writer);
            SPList taskList = SPContext.Current.Web.Lists["Tasks"];

            // Get items, order by title alphabetically and assign to taskListItems
            var taskListItems = from SPListItem tItem in taskList.Items
                                orderby tItem.Title
                                ascending select tItem;

            foreach (SPListItem taskItem in taskListItems)
                writer.WriteLine(taskItem.Title + "<br/>\n");
        }
    }
}

The bold text in the above code block is the LINQ statement to fetch all items in the SPList and order them ascending by Title. You can of course make much more complex queries using LINQ in order to fetch other objects based on different criteria.

This will produce a simple output like this, sorting the items alphabetically:

Summary and Download

This was a very (very) basic and simple example of how you can use any .NET 3.5 technology to get started with some new cool stuff.

I utilized a basic LINQ expression in this article which of course can be heavily modified if you want to retreive other things from your list(s). Perhaps a future article will take on some more advanced LINQ expressions in conjunction with SharePoint?! :-)

Anyway, you can download the sample project from here: Zimmergren.net35.LINQWebPart.zip

Thanks for tuning in and please leave a comment

As always, there's plenty of readers but few people showing their appreciation through the comments - please leave a comment :)

Hope it helps :-)

Technorati Tags: Microsoft, SharePoint, MOSS, WSS, LINQ, .NET, Integration

Published: Sep-28-08 | 15 Comments | 0 Links to this post