¿Cómo actualizar un registro en el marco de la entidad?

How to update a record in entity Framework?

Update Objects in Entity Framework 4.0 The steps to update an existing entity are quite simple. First retrieve an instance of the entity from the EntitySet (in our case ObjectSet), then edit the properties of the Entity and finally call SaveChanges() on the context.

Insert Data Use the DbSet. Add method to add a new entity to a context (instance of DbContext ), which will insert a new record in the database when you call the SaveChanges() method.

You can add multiple records or multiple objects using the AddRange method of DbSet as shown in the following code. The code creates a list of department objects and inserts two new departments to the list. We add the list to the context using the AddRange method.

During SaveChanges, the ObjectContext determines which fields were changed. In this example, only FirstName and LastName are changed. So, only those two values are sent into the command. To identify the row to be updated in the database, the ObjectContext uses the value of the EntityKey property.

In Entity Framework, the SaveChanges() method internally creates a transaction and wraps all INSERT, UPDATE and DELETE operations under it. Thus, each SaveChanges() method call creates a new transaction and executes database commands within it.

First the multiple rows (records) will be insert into an HTML Table and then the data from all the rows of the HTML Table will be sent to Controller using jQuery AJAX which will be ultimately saved to database using Entity Framework in ASP.Net MVC Razor.

Returns. The number of state entries written to the underlying database. This can include state entries for entities and/or relationships.

Now, when you add a new Student and call SaveChanges() method, EF will assign a newly generated id to the StudentID property. EF execute each INSERT command followed by SELECT scope_identity() statement. SCOPE_IDENTITY returns the last identity value inserted into an identity column in the same scope.

SaveChanges returns without error, but the name change does not persist in the database. OTOH, if I ADD a new product and the productID == 0, the new product is successfully added using the same repository method. The implementation stubs are as follows:

SaveChanges, marks it for being saved, but doesn’t actually commit until i do acceptallchanges.. but if something goes wrong.. i will need to rollback won’t i so that my object returns to its correct state? – mark smith May 10 ’09 at 19:32

If context1.SaveChanges () succeeds but context2.SaveChanges () fails the whole distributed transaction is aborted. But unfortunately the Entity Framework has already discarded the changes on context1, so you can’t replay or effectively log the failure.

SaveChanges is working fine for adds and deletes, but does not persist changes to column data, and I am not sure why. For example, changing a Product.Name from, say, “Kayak” to “Green Kayak” looks fine when debugging and setting a breakpoint on the SaveProduct method in the repository.