Questions about EntityDataSource and dynamic binding

Rushino · November 20th, 2010, 03:21 PM

Hello,

I was re-reading the chapter 14 of beginning asp.net in C# and vb and i was wondering about the EntityDataSource. I have some questions.

1- It is best pratices to use EntityDataSource or bind dynamically using LINQ with a GridView.

2- Is EntityDataSource working with LINQ for querying ? (SELECT data)

3- Is there a way too add insert, update features using LINQ with the EntityDataSource ? or it is done automatically ?

Big thanks!

Imar · November 22nd, 2010, 06:21 AM

Hi Rushino,

Quote:

1- It is best pratices to use EntityDataSource or bind dynamically using LINQ with a GridView.

It all depends.The data source can be an easy control to use for many scenarios. However, in other cases where you have complex querying logic, it may be easier to use a LINQ queryt.

Quote:

2- Is EntityDataSource working with LINQ for querying ? (SELECT data)

If I understand thw question correctly: yes; it has select parameters that enable you to create a query.

Quote:

3- Is there a way too add insert, update features using LINQ with the EntityDataSource ? or it is done automatically ?

Not sure I understand this question. What would you like to add?

Imar

Rushino · November 22nd, 2010, 09:01 AM

Hello Imar,

Again a big thanks for your reply and sorry because i may not have been that clear.

About question 1.

I asked if it was best practice due to fact that i had problems using dynamic declarative binding. My principal concern is about hte place where we should set up dynamic declarative binding. What is the best place to put the dynamic binding ? in which event ?.. cause sometimes i end up having no data in a GridView.. before doing some operations on the data itself.

About question 2.

I was wondering if the underlying query in an EntityDataSource was using LINQ instead of regular SQL. Or it is regular SQL ? Can you write a LINQ query directly in the select command of the datasource in the aspx. page ?

About question 3.

Does that EntityDataSource support aswell insert, update and delete query with LINQ ?

Thanks.

Imar · November 22nd, 2010, 09:55 AM

Hi Rushino,

1) For simple scenarios, the data source works fine. For more complex queries, I find LINQ queries in Code Behind easier to work with. You typivally do it in Page_Load.

2) Yes, it uses LINQ. The Where and Select properties enable you to define LINQ. For an example, see the file ManagePhotoAlbum.aspx. This LINQ query is then translated to SQL.

3) The technical answer is: yes. Since a standard EDS uses LINQ, it supports inserting, updating and deleting data. However, in reality the answer is probably no, as the control isn't very good in working with data coming from a complex query. For those scenarios, hand coding is a lot easier. This is explained on page 554 and further.

Cheers,

Imar

Rushino · November 22nd, 2010, 09:58 AM

Alright. Big thanks for these replies. Its all clear now.