CODEWITHSUNDEEP
pythonsqlitepyqt
Ahmed Wagdi
Ahmed Wagdi

Reputation: 4421

Getting the event of having a Sqlite Error

I am using python 2.7 with pyqt 4.10 and sqlite3

in my database, there is a foreign key between two table. I want to rise a GUI error to the user when he tries to delete the parent key that has values in the destination table associated with

the code : 

    deleted1 = self.listWidget.currentItem().text()
    deleted = unicode(deleted1)
    quit_title1 = 'تأكيد'
    quit_title = quit_title1.decode('utf-8')
    quit_msg1 = ' هل انت متأكد من مسح الفئة '
    quit_msg = quit_msg1.decode('utf-8')
    result = QtGui.QMessageBox.critical(Dialog, quit_title, quit_msg, QtGui.QMessageBox.Yes | QtGui.QMessageBox.No, QtGui.QMessageBox.No)
    if result == QtGui.QMessageBox.Yes:
        conn = sqlite3.connect('storage/container.db')
        conn.row_factory = lambda c, row: row[0]
        c = conn.cursor()
        c.execute("PRAGMA foreign_keys = 1")
        c.execute("DELETE FROM categories WHERE category_name = (?)", (deleted, ))
        conn.commit()
        conn.close()

its gives back the error : 

Traceback (most recent call last):
  File "C:\python\townoftechwarehouse\edit_category.py", line 102, in deleteing
    c.execute("DELETE FROM categories WHERE category_name = (?)", (deleted, ))
sqlite3.IntegrityError: FOREIGN KEY constraint failed

This error doesn't terminate the program , but it totally do nothing in the UI and i want the user to know that he is enable to delete it because there is connections with it in the database

Upvotes: 0

Views: 57

Answers (1)

Tobias
Tobias

Reputation: 121

Just wrap it in try/except and catch sqlite3.IntegrityError. Then you can do pretty much whatever if that error occur.

(Since you are initiating the database and doing everything in on go here i would suggest a bit of refactoring into several functions..)

But here is an example, ive skipped to GUI parts.

deleted1 = self.listWidget.currentItem().text()
deleted = unicode(deleted1)
quit_title1 = 'تأكيد'
quit_title = quit_title1.decode('utf-8')
quit_msg1 = ' هل انت متأكد من مسح الفئة '
quit_msg = quit_msg1.decode('utf-8')
result = QtGui.QMessageBox.critical(Dialog, quit_title, quit_msg, QtGui.QMessageBox.Yes | QtGui.QMessageBox.No, QtGui.QMessageBox.No)
if result == QtGui.QMessageBox.Yes:
    try:
        conn = sqlite3.connect('storage/container.db')
        conn.row_factory = lambda c, row: row[0]
        c = conn.cursor()
        c.execute("PRAGMA foreign_keys = 1")
        c.execute("DELETE FROM categories WHERE category_name = (?)", (deleted, ))
        conn.commit()
        conn.close()
    except sqlite3.IntegrityError:
        # Do whatever

Upvotes: 1

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