Try It Out Pages 555 to 561

marcin · April 13th, 2011, 04:43 AM

Hi
Greetings to everyone

I have a problem with the try it out on pages 555 up to 561.
And i have two pottential problems:

In the table Review, where the Id column has (Is Identity) to Yes, when i try to add new review, this code shows up:
Cannot insert explicit value for identity column in table 'Review' when IDENTITY_INSERT is set to OFF. And it point to the:
mojaEntity.SaveChanges(); where mojaEntity is myEntity.

Another thing, looking like from dark side of the force,
if the (Is Identity) switched to No, and then i try add new review through AddEditReviewHandCoded.aspx, this error comes up:

Violation of PRIMARY KEY constraint 'PK_Review'. Cannot insert duplicate key in object 'dbo.Review'. The duplicate key value is (0).
The statement has been terminated.

How i can fix it?
~Thanks very much for your help

Imar · April 13th, 2011, 04:48 AM

Hi there,

What this looks like is that you set the Identity field at the database level *after* you created the Entity Framework mode. This way, EF doesn't know the column is generated by the data store and tries to submit its underlying value instead (which is zero as the default for an integer) when you save the changes to the data.

There are a few ways to fix it:

1. Delete the tables from the EF diagram and add them again.

2. Select the Id column in EF designer and open its Properties Grid (F4). Then set StoreGeneratedPattern to Identity, save your changes and try again.

3.; Try to update the model. Right-click the design surface of the EF diagram and choose Update Model from Database and follow the on-screen instructions.

Hope this helps, and if not please let me know.

Cheers,

Imar

marcin · April 13th, 2011, 05:06 AM

Wow!!!!!!!!!!!!

Thanks for such fast answer. Solution number 3 worked. Now, i won't forget that i have to refresh ef every single time i do something with the tables.
You are the Man Imar!!!

Imar · April 13th, 2011, 05:10 AM

You're welcome.

And yes, you need to refresh the model every time you make a change in the database. The model is saved in XML files (the .dbml file) and code files (.cs or .vb) and it's not automatically refreshed or recompiled (which is a good thing as it could otherwise break your code) when you change the database.

Cheers,

Imar