String or Binary Data Would Be Truncated Error

Question

I'm using Linq to SQL with SQL 2005. I'm parsing a large fixed width file and importing the data into SQL via custom entities that I have mapped to the database using property attributes.

The program runs for about 240 records before throwing this error. I've checked the columns (all four of them) and the data it's trying to put in and it shouldn't be throwing this error. I've even gone so far as to change the columns from varchar to text, and it still throws the error. When I manually insert the same values, they insert fine.

Is there a known bug or anything in Linq to SQL? I'm calling context.submitall() on every loop to insert. I've read that .NET 3.5 SP1 gives better error messages from SQL, but I'm still not seeing anything.

Thanks for any help.

Answer 1

Is it possible that you've changed your schema since you built the Linq to SQL classes? The designer entities won't be updated when you change your SQL schema unless you delete/recreate the class in the designer or hand-edit the properties for the designer-generated class. I know that it keeps track of the column width for string (varchar) columns in the class -- though I don't know if it actually checks it before submitting or just keeps it as a reference for any validation that you would do. I have seen similar problems with things like autogenerated ids, though, that were solved by updating the class in the designer.

Answer 2

Well, I found the bug, and it was definitely not a problem with Linq or with SQL. I was chopping up and changing properties on another object, not realizing that it was now attached to SQL via Linq, and it was that object throwing the errors.

Lesson learned: Do not alter properties directly on an object unless you really want to change them, and especially if it's attached to the data context.