When I dispose the DbContext, how I can save changes later ?

Question

I know that I should dispose the DbContext as soon as possible. but I have a TreeViewModel where each node is a an ItemViewModel that query MyDbContext to load data when IsExpanded is set to true. let's say that after the expand, I disposed MyDbContext, so when the user want to expand another node, an error will occure...

the TreeView should be always visible in my Descktop Application, so he can browse the Products, rename them and change prices...

so, Should I dispose MyDbContext after each operation in this scenario or what ?

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AAK

Answer 1

hello,

If we consider an MVC pattern... TreeView is a view that has no knowledege/concern of the underlying model or persistence layer.

So, imho, you should design a controller that feeds your view with data on demand. Such controller create and dispose context ar whatever he needs.

By the way, your description of the application makes me think to an Excel WorkSheet: good for a single user. If you have no more than one user... let the context live :)

Sincerely yours

thierry

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thierry

Answer 2

thanks for the reply. Sorry I am new to this, what you mean by single user ? any desktop application is for a single user or not ? how can many users use the same application ?

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AAK

Answer 3

On 6/5/2012 5:21 AM, Ahmad El Kerdi wrote:

> I know that I should dispose the DbContext as soon as possible. but I

> have a TreeViewModel where each node is a an ItemViewModel that query

> MyDbContext to load data when IsExpanded is set to true. let's say that

> after the expand, I disposed MyDbContext, so when the user want to

> expand another node, an error will occure...

>

> the TreeView should be always visible in my Descktop Application, so he

> can browse the Products, rename them and change prices...

>

> so, Should I dispose MyDbContext after each operation in this scenario

> or what ?

>

If this is a fat-client application where the entire application,

database and everything else is local to the user's machine, then you

can level the database connection open and close the connection when the

user exits the program. No one else but the user on the machine is using

the application and the database.

 

If this is a thin-client application where multiple users on different

machines are using the same database remotely, then you need to open and

close connections with the database when access is completed.  In doing

that, it doesn't block other users from using the remote database.

 

Answer 4

aha.... I think that I should read more about this, thanks a lot, I think that my application will be a fat-client application. This is the first time that i know that in this scenario, I can leave the connection open ! thanks a lot...

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AAK