I need to use a many to many relationship in my project and since Dynamic Data doesn't support it natively, I would like to ask for a sample of an implementation of something like it.
I'm specifically looking for a way to both create new instances of the target entity and add a new m2m relationship to a record as well as using existing instances to create the relationship.
I'm on a tight schedule, so any help is really appreciated.
David Ebbo (the architect for Dynamic Data) posted a Many-to-Many field template on his blog. Note that this solution is specifically for Entity Framework.
Related
I'm a beginner and it's the first time i hear this word outside the database world. So what does this means here:
In this case, yes. Generators are nice when there is a one-to-one
relationship between requests and responses, but when there is a
one-to-many fanout as seen here (or similar situations that arise with the
streaming_callbacks seen elsewhere in Tornado), I think it's cleaner to
just use callbacks than to try and fit everything into a generator.
Can you provide some application that uses one-to-one and one-to-many?
It's about database relationships, how an entry can be related to another or to many others.
For example, you have an User table and a Settings table.
One user is related to one settings entry. That's one to one.
Same think with table User and table articles:
One user wrote many articles. That's one to many.
You could try to read this:
http://net.tutsplus.com/tutorials/databases/sql-for-beginners-part-3-database-relationships/
I hope it helped.
Can anyone tell how to update table rows dynamically in entity framework? I am new in entity framework. Thanks in advance.
This is a pretty general question, but what you need to do is basically this:
Access your data context.
Get a given object (/record) from your context (/database).
Change the object.
Call SaveChanges() on the data context.
If you are learning EF a site that helped me a lot when I was learning it is http://msdn.microsoft.com/en-us/library/gg696194(VS.103).aspx. It contains lots of information in problem/solution format. You can also look at this book:
http://www.amazon.com/Programming-Entity-Framework-Building-Centric/dp/0596807260/ref=sr_1_1?ie=UTF8&qid=1355991856&sr=8-1&keywords=entity+framework
or this book:
http://www.amazon.com/Programming-Entity-Framework-Code-First/dp/1449312942/ref=sr_1_4?ie=UTF8&qid=1355991858&sr=8-4&keywords=entity+framework
which are both quite useful depending on whether you wish to use the designer or Code First.
I'm attempting to setup Entity Framework using Code First on an existing database. The database isnt in great shape (poor naming convention and some constraints are needed). The application I'm building is an MVC app. I have a "Model", "Repository", and "Web" (mvc) tiers.
To setup EF and map my model objects (POCO objects), is it required that I match my objects to database tables? Can I, instead, use my own stored procedures for CRUD operations? Would it help if I use WCF data services?
I'm planning on using fluent configurations to map my objects, but having some issues due to the database schema. I'm know considering redesigning the database just to get EF to map correctly. Any suggestions would be greatly appreciated!!
Looks awfully similar to this question:
Does Entity Framework Code First support stored procedures?
The answers there may be helpful to you, as well as the discussion surrounding how Code First and Stored Procedures don't make a whole lot of sense.
Wow, Julie Lerman answered!
Yes, it's possible, but not particularly easy. In particular, you must call context.Database.SqlQuery<T>() where T is the entity type you want to return, and your SQL must match up to that entity type. Otherwise, you will have to massage a result set into a type.
In general, you will have to do most of this manually, although you could probably figure out a T4 template to generate it for you, or maybe use some other tool like CodeSmith.
I am trying to understand how to create a complex POCO which in the backend tied to a stored procedure or multiple tables. All the examples I have seen are simple one table to one entity or two tables. Could some one point me to a link or example on how to create a complex POCO which talks to stored procedure or multiple table. Or is it just my imagination?
Thanks,
Found the following link and it has some good information, thought share it with anyone interested.
http://blogs.msdn.com/b/adonet/archive/2009/05/21/poco-in-the-entity-framework-part-1-the-experience.aspx
I made an Entity database and it generated all the tables but it seems to have forgotten about the aspnet_usersinRoles table.
I don't know why it would skip this one or how to add it.
When in I look in the Model Browser through VS2008 I see the the aspnet_UsersInRoles table.
No, it didn't "forget" about aspnet_UsersInRoles. This table consists only of two foreign keys to other tables. Since you've mapped those as well, aspnet_UsersInRoles is subsumed into a many to many relationship within your model. In other words, it's there; it just isn't shown as a separate entity, since it serves only to represent a relationship between two other entities.
This is a limitation of entity framework apparently. I came across this very same problem while trying to implement an RIA solution to bridge ASP.NET membership and Silverlight.
This link has a workaround, although I never really got it to work exactly how I wanted. I ended going with plain ol' Linq2SQL.