How to get data from database with Entity Framework?

Question

Using c#, net.4.5 vs 2012

I'm trying to get data from database using Entity Framework.

At first idea was use code like below - it's must allow to add, delete and update entries in dataGridView, and than just save changes using context.SaveChanges() (method from ObjectSet, if I'm not wrong)

using (LibraryEntities context = new LibraryEntities())
{
            var query = (from c in context.Book select c).First();
            DataGridView dgv = new DataGridView();
            dgv.DataSource = context.Book;
}

Result - exception

Data binding directly to a store query (DbSet, DbQuery, DbSqlQuery) is not supported...

Then I try a little bit changed code:

using (LibraryEntities context = new LibraryEntities())
{
    var query = (from c in context.Book select c).First();
    DataGridView dgv = new DataGridView();
    dgv.DataSource = query;
}

but have same issue with exception

Data binding directly to a store query (DbSet, DbQuery, DbSqlQuery) is not supported...

At last try to convert all to List():

using (LibraryLib.LibraryEntities context = new LibraryLib.LibraryEntities())
{
    DataGridView dgv = new DataGridView();
    dgv.DataSource = (from c in context.Book select c).ToList();
}

As and expected, I got all db entries in DataGridView, but I can't add, update and delete any entries.

enter image description here

And the question is - how can I change db in dataGridView and than save it with DbContext.SaveChanges()

@ElliotTereschuk, SO is an english only site. Google offer's this as a translation Hey. Try to consider the ready examples are not quite understand everything — crthompson
– crthompson, Commented Jan 13, 2014 at 18:57
@paqogomez Thanks, I know - it's because of rare case of seeing Ukrainian people here ;) — nasytnyk
– nasytnyk, Commented Jan 13, 2014 at 18:59
@Elliot Tereschuk Привіт, а що саме нечітко описано? / HI, what not correctly described in question? — hbk
– hbk, Commented Jan 13, 2014 at 19:04
@Elliot Tereschuk. так, але коли я приводжу до колекції, я отримую результат. проблема в тому. що я не можу видалити або додати запис до DataGridView В останньому варіанті - все добре працює. Що хочу я - пернести всю базу даних до DataGridView. редагувати її (видаляти міняти значення додавати рядки. тощо). А потім повністю зберегти. Як це зробити?, адже спробувавши так як описано в книжці - видає виключення. — hbk
– hbk, Commented Jan 13, 2014 at 19:19
@Elliot Tereschuk. Yep, but when i'll try to get collection - all works, but i cant do anything in DataGridView. what I want - it's to load all db in DataGridView than modify its entities and change them (mean add, del or update) and than just save it using DbContext.SaveChanges() - like described in mny of tutorials that i seen - but i cant due to existing of exception — hbk
– hbk, Commented Jan 13, 2014 at 19:20

potehin143 · Accepted Answer · 2014-01-13 19:29:23Z

2

Is it winforms? if yes, you have to use BindingSource to link data

        BindingSource bs = new BindingSource();
        bs.DataSource = typeof(Book); // Book is a type of your Entity class

        db.Book.ToList().ForEach(n => bs.Add(n)); 
        dgv.DataSource = bs;

now it's editable. And to store changes just call db.SaveChanges();

your way to assing List to DataGrid is valid for WPF. What about to migrate there?

answered Jan 13, 2014 at 19:29

potehin143

5314 silver badges9 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

hbk Over a year ago

Yep, i use WinForms, I'm thinking about wpf, but currently i'm just studing (in free from work time) c#. First of all try to understand main milestones. Your proposal perfect - as I understand I must to add some "buffer" for data before use it. Thanks

DeepakKhetwal · Accepted Answer · 2014-01-14 02:23:49Z

0

I would suggest to use repository pattern with unitofwork pattern which means a repository class which will handle all CRUD operations and unit of work class to commit all the changes together.

answered Jan 14, 2014 at 2:23

DeepakKhetwal

863 bronze badges

2 Comments

hbk Over a year ago

Can you provide any link for getting some tutorial or additional information regarding this pattern, if be honestly - never hear about this

DeepakKhetwal Over a year ago

codeproject.com/Articles/37155/… For Unitofwork - create T4 template

Collectives™ on Stack Overflow

How to get data from database with Entity Framework?

2 Answers 2

1 Comment

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related