I found this something interesting while wandering over community which I would like to share.
The post is whole about: DBML is not considering
the table
field's "Default value or Binding" setting which is a NotNull. I mean
the field which can not be null but having default value set needs to be set IsDbGenerated = true in DBML file explicitly.Consider this situation: There is a simple tblEmployee table with below structure: The fields are simple. EmployeeID is a Primary Key with Identity Specification = True with Identity Seed = 1 to autogenerate numeric value for this
field. EmployeeName and their EmailAddress to store in rest of 2 fields. And
the last one is "DateAdded" with DateTime datatype which doesn't allow NULL but having Default Value/Binding with "GetDate()". That means if we don't pass any value to this
field then SQL will insert current date in "DateAdded"
field.So, I start with a new website, add a DBML file and dropped
the said table to generate LINQ To SQL context class. Finally, I write a simple code snippet to insert data into
the tblEmployee table; BUT, I am not passing any value to "DateAdded"
field. Because I am considering SQL Server's "Default Value or Binding (GetDate())" setting to this
field and understand that SQL will insert current date to this
field. using (TestDatabaseDataContext context = new TestDatabaseDataContext()) { tblEmployee tblEmpObjet = new tblEmployee(); tblEmpObjet.EmployeeName = "KaushaL"; tblEmpObjet.EmployeeEmailAddress = "
[email protected]"; context.tblEmployees.InsertOnSubmit(tblEmpObjet); context.SubmitChanges(); }Here comes
the twist when application give me below error: This is something not expecting!
From the error it clearly depicts that LINQ is passing NULL value to "DateAdded"
Field while according to my understanding it should respect Sql Server's "Default value or Binding" setting for this
field. A bit googling and I found very interesting related to this problem.When we set Primary Key to any
field with "Identity Specification" Property set to true; DBML set one important property "IsDbGenerated=true" for this
field. BUT, when we set "Default Value or Biding" property for some field; we need to explicitly tell
the DBML/LINQ to let it know that this
field is having default binding at DB side that needs to be respected if I don't pass any value. So,
the solution is: You need to explicitly set "IsDbGenerated=true" for such
field to tell
the LINQ that
the field is having default value or binding at Sql Server side so, please don't worry if i don't pass any value for it.You can select
the field and set this property
from property window in DBML Designer file or write
the property in DBML.Designer.cs file directly. I have attached a working example with required table script with this post here. I hope this would be helpful for someone hunting for
the same. Happy Discovery!
