Foreign key constraints in sqlite3

markjgreenwood · March 27th, 2015, 01:59 PM

When I try the example (step 3, add an item) on p. 152, I don't get the exception saying the foreign key constraint failed. The database just happily adds the item.

In Ch. 3 p. 151, the text says: "Notice, too, that you set the Foreign_Keys pragma in the initDB() function to ensure that all transactions are checked for referential integrity."

However, the code for initDB() looks like this:

Code:

def initDB(filename=None):
    global db, cursor
    if not filename:
        filename = 'lendy.db'
    try:
        db = sql.connect(filename)
        cursor = db.cursor()
    except:
        print("Error connecting to ", filname)
        cursor = None
        raise

I don't see anything invoking the Foreign_Keys pragma... is something missing?

Alan G · March 29th, 2015, 04:08 AM

There is an error in the book - a missing line with the required PRAGMA statement.
My apologies. Check the code on the download site, it is correct.

If in doubt always look at the download code, the code in the book was cut n pasted,
then reformated from that code so the download code is effectively the baseline.

Alan G.