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!
