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BOOK: Python Projects
This is the forum to discuss the Wrox book Python Projects Laura Cassell, Alan Gauld; ISBN: 978-1-118-90866-2
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Old March 27th, 2015, 01:59 PM
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Default Foreign key constraints in sqlite3

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:
def initDB(filename=None):
    global db, cursor
    if not filename:
        filename = 'lendy.db'
        db = sql.connect(filename)
        cursor = db.cursor()
        print("Error connecting to ", filname)
        cursor = None
I don't see anything invoking the Foreign_Keys pragma... is something missing?
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Old March 29th, 2015, 04:08 AM
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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.

Last edited by Alan G; March 29th, 2015 at 04:10 AM..
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