I'm new to the Entity Framework.
I have a SQL Function that returns the age for a given birthday.
(http://www.sql-server-helper.com/functions/get-age.aspx)
And I want to use it with linq. I know it's possible. I've read it here:
http://blogs.msdn.com/efdesign/archive/2009/01/07/model-defined-functions.aspx
http://blogs.msdn.com/efdesign/archive/2008/10/08/edm-and-store-functions-exposed-in-linq.aspx
but it seems this is part of the EF extentions (which I have) or that it is still in development.
Can anyone help me with this?
Thank you.
Model defined functions are not in the shipping Entity Framework, and I don't think they are in the extensions, either. As far as I know, they are a new feature planned for .NET 4.0. I don't know if they are in the Community Technology Preview of that. You can see a demo of model defined functions if you watch the Entity Framework presentation from PDC. But they are certainly not in .NET 3.5 SP1.
As a workaround, you could define a computed column on your table which used the function and then map that column instead of mapping the function directly.
You might be able to do a "FunctionImportMapping" see msdn for more info..
You could definitley do it that way if you exposed it as a sproc, I've not tried with just a function tho..
Related
I want to know if there is a way to generate the class dynamically at runtime. I want to use it in Entity framework code first.
Consider if I have 100 tables(or connect to unknown database) I will have to create model/POCO for each table in EF Code First, instead of this I want to generate the POCO class and all its properties at runtime based on the database connected.
Probably not.
Consider this... If the classes aren't defined before compilation, then how is any other code going to use them? If no other code is going to use them, why do you need them?
You can generate objects based on the table schema at design time. Doesn't Entity Framework in fact do this already?
I realize that I've linked to something that is "database first" instead of "code first" but, well, that's what you're asking:
I want to use it in Entity framework code first.
[...]
I will have to create model/POCO for each table in EF
You have a database, and you want to generate models based on the schema of that database. That's database-first.
You can use the EF Power Tools (beta 3) for Visual Studio 2010 or 2012 to reverse engineer a database to POCOs. After installation, right click on a project and select Reverse Engineer Code First under the new Entity Framework menu group.
The Power tools: http://visualstudiogallery.msdn.microsoft.com/72a60b14-1581-4b9b-89f2-846072eff19d
Rowan Miller has a blog post about this, and some advanced uses: http://romiller.com/2012/05/09/customizing-reverse-engineer-code-first-in-the-ef-power-tools/
The method - Entity Framework Code-First - looks good. But its very difficult to create all the classes for a large database.
Is there any easy way to generate the Entity Framework Code-First classes?
You can use the recently released Entity Framework Power Tools CTP1. The tool gives you the ability to reverse engineer code first, meaning the Database will be mapped to Code.
Note that all tables in your large database will be mapped. There currently is no way to choose which tables will be mapped to code. Reading through the comments, this feature will most likely be implemented in a future release.
The point of EF Code-First is that you define your domain model in code, then your user-interface and database can be easily generated from that domain model. This has a number of advantages including reducing the amount of tedious code which needs to be written, and helping to ensure your database, your domain model, and your UI match each other.
However, at some point you are going to have to write your domain model - there's no way that can be "generated" (by which I assume you mean computer-generated) as it is personal to your application.
If I've misunderstood your question, please leave a comment and I'll update my answer.
If you want to use the code-first model, but already have an existing database, you can use the Entity Framework Power Tools to generate classes.
If you're reading this after May/2012, the above tool may be out of beta!
No there is no way to generate classes for you if you are using code-first. Code first means that there is no model and no database so you can't generate classes unless you have some upfront design in any case system (UML) which will autogenerate code for you. Simply generating classes without any input about how they should look like sounds like AI from Sci-fi, doesn't it?
If you already have databse you are not using code first but database first. In such case you can have your classes generated.
Check out the link below. It's a program that will generate POCO classes from your databases. I think that's what you're looking for.
http://msormcodegen.codeplex.com/
Generate the code from the database first using database first generation and then modify the resulting code to start your code first version
HI,
I'm a bit lost with Entity Framework ...
Here is the context : Desktop Application (C# / Winform)
VS 2010 (SP1), SQL COMPACT (4.0 for identity), ... for now EF 4 (default version)
I've just started a new app and i've thinking of using EF because it seems that it's a quickest way to design both model and database (i know that it's not the best way but my project is not critical).
building the model with graphic designer is very convenient, i can easyly build the sql compact schema' and i can access model class directly.
But i need to add some feature to my model class (overriding ToString for example or some basics functions), so it seem that i need to make POCO classes.
But the problem is after generating these classes, how can i update these without losing added code , what's the best way to doing that ? partial class ?
Moreover, it seem that EF dev are focusing on Code First, so does it mean that Entity Model are already deprecated ?
EF generates partial classes, so you are right - in order not to lose the extra code you add, you need to create separate files and use the partial class feature. Those files won't be re-written once the model is saved.
Moreover, it seem that EF dev are
focusing on Code First, so does it
mean that Entity Model are already
deprecated ?
No, it's not deprecated. Using Code First is just a matter of preference, but you can feel free to use the EDM - it's not going anywhere.
I am aware that table valued functions are not supported in previous versions of entity framework. I was wondering if this is now supported in EF 4? I cant see my functions in the edm designer so i'm guessing they are not supported unless I am doing something wrong?
If they are not supported is there a workaround? My table valued function takes a single parameter.
Yes, you can definitely use Table-Valued functions with EF. Here's a great link on how this can be achieved: http://blog.ondrejsv.com/post/Using-table-valued-database-functions-with-Entity-Framework-40.aspx#comment
It appears as you can use them...
Link
It uses the GetFriends() table valued function. Still i don't really know how to use it.
This question is an extension of another question, but I think it warrants its own thread. See See Silverlight Question
I have a stored procedure (SQL 2005) that returns a dynamic data set (different columns/schema) each time it is called.
I want to consume this in Silverlight 3.0 so I need to somehow wire this up using Entity Framework and RIA Services. I also need this to be Bindable (Silverlight Grid) so I need these dynamic columns to be accessible via properties (grid limitation). Any ideas?
In the currently shipping version of the Entity Framework, the only type of stored procedures you can map are those which return entity types. The mapping is done, generally, before you compile, although it seems at least theoretically possible to generate Entity Framework metadata at runtime.
Therefore, I see a few choices.
Give up on the whole idea of consuming a procedure which does not return a defined schema. You will never be able to map such a procedure before you compile.
Dynamically generate EDMX at runtime in order to map an entity type to the expected output columns of the procedure before you invoke. Note that the current version of the Entity Framework is a bit finicky about the columns a procedure returns; you can find documentation about this on MSDN.
In .NET 4.0, there are new features which allow you to inform the Entity Framework about your client schema at runtime without having to generate EDMX first. You might be able to leverage these features in order to map some entity type to the expected output columns of the procedure.
Again, in .NET 4.0, there may be support for procs which return scalar values. I can't remember if this is the case or not.
You can always get a standard database connection from the entity connection and execute the procedure directly, using regular SqlCommands. Unfortunately, this makes your code database-provider-specific, but it may be the simplest solution to your problem. Indeed, using such a procedure at all is already database-server-specific.
You might use a WCF web service wraper for accesing your SP and use the WCF service as data source Brad Abrams has a way to do that on his series of articles on RIA Services