NET Standard Query Operators are not a hard-coded list, and can be added to and replaced by any developer. This enables very powerful domain specific implementations. This means that you will be able to trivially build efficient web data paging over lots of relational data note: until then you can use the techniques listed here.
Step 5: More Fun with. In addition to returning sequences of data, we can use. The below samples show examples of how to-do this:. First ;. Distance ;. Note that the last two examples above use the new Lambda Expression support — which enable fragments of code like delegates that can operate on top of data to compute a result. You can build your own. NET Query Operators that use these for example: you could build domain specific ones to calculate shipping costs or payroll tax.
Everything is strongly-typed, and will support intellisense and compilation checking support. The output of the above sample looks like so:. Step 6: Anonymous Types. This allows you to easily create and use type structures inline without having to formally declare their object model instead it can be inferred by the initialization of the data.
For example, consider a scenario where you are working against a database or strongly-typed collection that has many properties — but you only really care about a few of them. Rather than create and work against the full type, it might be useful to only return those properties that you need.
The types of these properties are automatically calculated based on the value of their initial assignment in this case a string and an int , and when databound to the GridView produce an output like so:. Step 7: Anonymous Types again. The previous sample showed a basic example of using anonymous types to custom-shape the output of a LINQ query.
The below sample provides a richer and more practical scenario. It transforms our list of cities into a hierarchical result collection — where we group the results around countries using an anonymous type that we define that contains the country name, a sub-collection list of city details, and the sum of the total distance of all cities within the country computed using a lambda expression like we demonstrated in step5 above :.
Country into loc. The GridView on our. NET 2. This generates output like so:. Note that all of the databind syntax and hierarchical binding support in the. What is new and I think very cool is the data shaping capabilities provided by anonymous types and LINQ — which makes binding hierarchical data against ASP. NET controls very easy. Next Steps. All of my samples above were against in-memory collections. They show you how you will be able to use LINQ against any.
NET object model includes all the ones you have already. What is great about the LINQ project is that the syntax and concepts are the same across all of its uses — so once you learn how to use LINQ against an array or collection, you also know all the concepts needed to work against a database or even XML file. For example, if you use DLINQ to generate a Northwinds database mapping of Suppliers and their Products no code is required to set this up , the below code is all you need to write to obtain and databind a hierarchical database result against a GridView like we did above note: we are using the same data-shaping technique as our previous sample to only require fetching two columns from the database, and automatically join the products of each supplier as a hierarchical group result :.
No custom SQL syntax or code is required — this is all that needs to be written to efficiently fetch and populate hierarchical data now note: only the rows and columns needed will be fetched -- DLINQ can use the remote function support within LINQ so that it does not need to materialize or fetch the full database table or all columns from a row. And it is all type-safe, with full compiler checking, intellisense, and debugging supported. Once you know LINQ you will know all the basics needed to program against any of them.
Hopefully this provides a glimpse of some of the cool new things coming. You can also download and run all of the samples I built above from this. ZIP file here. Hope this helps,. Thanks for the update Scott. I can't wait to start trying this stuff out. Keep up the good work. Hi Scott, Great article, thanks.
Just one question: select location. Take 5 ; Why do you skip number 1 and not number 0? If I'm right, you are selected lines and s, it should start at 0. Can you give me more details? Can you confirm that you have had? The error could be coming from that. Hope this helps, Scott P.
Lastly -- if the above two suggestions don't work, please try running the sample using the built-in VS web-server to see if that makes a difference it shouldn't -- but maybe it does. Hi Tom, Skip takes the number of results to skip in the sequence and not the row to start with. Hope this helps, Scott. Hi Paketim, We are looking to ship the second half of next year. We will start having full Orcas CTP drops of all technologies starting later this summer, and will also have a go-live license of Orcas before the final RTM date.
So not too far off now when you can use the above techniques in production. However, i have got excited by new datahandling functionality being introduced in the past only to find that the are usually many reasons why it can't be used in an enterprise n-tier project.
Many Thanks. After I type using System. After I type GridView1. Pleased you stated your C examples are in C 3. Add loc ; to make it work. Of course, when you move this to a separate PlacesVisited class, it is more difficult because you cannot return an anonymous type. However you could still do this and just return type Object provided you perform your query within the method , as ASP. NET will still correctly will databind against it using reflection. And I am sure eventually Orcas will include a standard refactor to extract the type!
Nice stuff isnt it! David Taylor. Our expectation is that existing enterprise data providers will move to support LINQ against them relatively quickly after Orcas ships to give developers even more flexibility to choose from. Windows PowerShell Monad. Scott, if you have not yet had a chance, I encourage you to look at Windows PowerShell.
A few weeks ago I didnt know what a Monad Comprehension was actually I still dont Hi VC, The language services support for C 3. Obviously this will be fully supported by VS in the future though. Compilation error messages are accurate and correct though -- so even if you don't get intellisense you will get compile error checking with the May CTP.
Nice sample David! Hi Paul, Yep -- you can use all of this with Atlas. This is useful for a lot of data scenarios especially filtering and calculations , and the Lamdbda syntax is much terser than what you'd need to otherwise write today. They are also fully type-safe for compile-time and intellisense support. I was wondering whether Orcas is going to ship with a new major CLR and Framework version, or whether it will be built on top of the 2.
I'm particularly wondering because I feel strongly that anonymous types ought to have CLR-level support so that it's possible, at a language level, to provide a syntax for referring to them explicitly and have equivalent anonymous types remain equivalent across assemblies. Hi Stuart, We are definitely adding new Framework libraries in Orcas. We are making some changes to the CLR for that release, but are also being careful to keep a high runtime compat bar to ease deployments the following release will then have more engine additions.
I'll follow up with some folks to discuss whether there might be a nice syntax for doing this. The foreach loop executes the query on the data source and get the result and then iterates over the result set. After writing LINQ query, it must be executed to get the result. C ASP. Skill Tests ASP. Try it. Contains 'a' select name;. Linq System. Mapping The former namespace provides classes that allow you to interact with database whereas the later namespace contains classes and attributes that are used to generate entity classes representing the tables.
Create an entity class for Employees table Just like anything else in. SOme of the important ones are listed below: Name: Name of the table column DbType: Data type of the table column not. NET data type! Create a strongly typed data context Any data driven application has some data source from which data is fed into the system.
Developing a Web Form Design the default web form as shown below: The web form consists of a textbox to filter records based on first name or last name. ConnectionStrings ["connstr"].
Employee where c. Contains criteria select c. Employee where emp. Text; emp. Text; db. InsertOnSubmit emp ; db. SubmitChanges ; BindGridView string. The Update operation is similar to Insert with little change. SelectedValue select emp; results. Text; results. SelectedValue ; db. DeleteOnSubmit results ; db. That's it!
Run the web form and test its functionality. Bipin Joshi is an independent software consultant, trainer, author, and meditation teacher. He conducts instructor-led online training courses in ASP. NET family of technologies for individuals and small groups. He is a published author and has authored or co-authored books for Apress and Wrox press. Having embraced the Yoga way of life he also teaches Ajapa Yoga to interested individuals.
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