The “X” property on “Y” could not be set to a 'null' value. You must set this property to a non-null value of type 'Int32'

Question

When I run my application and I click a specific button I get the error:

\"The \"X\" property on \"Y\" could not be set to a \'null\' value. You must set thi         


        

Answer 1

For me the following Steps corrected the Error:

1. Remove the 'X'-Property from the 'Y'-Table
2. Save EDMX
3. build Database from Model
4. compile
5. Add the 'X'-Property to 'Y'-Table again (with non-nullable and int16)
6. Save EDMX
7. build Database from Model
8. compile

Answer 2

 "The "X" property on "Y" could not be set to a 'null' value. You must set this property to a non-null value of type 'Int32'."

In your EDMX, if you go under your Y table and click on X column, right-click, click on Properties, scroll down to Nullable and change from False to True.

If you get a "mapping fragment" error, you'll have to delete the table from the EDMX and re-add it, because in the Model Browser it stores the table properties and the only way to refresh that (that I know of) is to delete the table from the Model Browser under <database>.Store then retrieving it using Update Model from Database.. command.

Answer 3

This may happen when the database table allows NULL and there are records that have a null value and you try to read this record with EF and the mapping class does not allow a null value.

The solution is either change the database table so that it does not allow null or change your class to allow null.

Answer 4

In my case in created view in DB column that I select that contains null value I change that value by this select statement:

Before my change

 select 
     ..., GroupUuId , ..

after my change

 select 
     ..., ISNULL(GroupUuId, 0), ... 

Sorry for my bad English

Answer 5

I just replace data type int to int32?

public Int32 Field{ get; set; }

to

public Int32? Field{ get; set; }

and the problem is solved