entity framwrok4 error for computed column

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Hi experts

I got a table in SQL Server 2008 has 10 columns and one of them is a computet column

(([FirstName]+n' ')+[LastName])

But when I try to insert a new object to the table with entityframework 4, it can't and an exception like computed column can not be null

But if I remove the column form the table it can be inserted.

I use .NETFramework 4 and Visual Stadio 2010

What can I do to solve this problem it's necessary to have computed column and EF4 doesn't work for this.
I don't want to use SP (Stored Procedure) too?

Posted 5-May-12 1:47am

Vartan Khachatourian

Updated 5-May-12 11:24am

Shahin Khorshidnia

v3

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Comments

[no name] 5-May-12 8:07am

If you have a constraint on the computed column that is cannot be null, remove the constraint.

Vartan Khachatourian 5-May-12 8:45am

it's not null because firstname and lastname are not null

[no name] 5-May-12 8:47am

What exactly does that have to do with a constraint on the database column?

Vartan Khachatourian 5-May-12 8:51am

there is not any constraint on this column

[no name] 5-May-12 8:52am

Well that is where you are getting that error.

Vartan Khachatourian 5-May-12 8:53am

well whats your solution?

Zoltán Zörgő 5-May-12 17:04pm

Are you using
[DatabaseGenerated(DatabaseGeneratedOption.Computed)]
attribute?

Vartan Khachatourian 5-May-12 17:25pm

no but if i must use it , where am i supposed to add the arrtibute?

Zoltán Zörgő 5-May-12 17:49pm

Well this is a DataAnnotation attribute. You should put it where your other attibutes are. Are you following database-first or code-firts approach? I suppose the first one. In this case it is a little bit difficult to add attributes: you can use partial classes. Here you have an example: http://www.asp.net/mvc/tutorials/older-versions/models-(data)/validation-with-the-data-annotation-validators-cs

Zoltán Zörgő 6-May-12 0:34am

Another: you can use a read-only not mapped property in EF instead of calculate in on sql side. You will probalby gain performance too.

Vartan Khachatourian 6-May-12 6:01am

thank you i try it

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