OperationalError from SQlite that indicates a permissions problem. #2508

Mary011196 · 2017-04-11T21:50:25Z

Fixes 1676.

…database file.

mention-bot · 2017-04-11T21:50:27Z

@Mary011196, thanks for your PR! By analyzing the history of the files in this pull request, we identified @sampsyo, @geigerzaehler and @brunal to be potential reviewers.

sampsyo · 2017-04-11T22:17:04Z

beets/ui/__init__.py

            util.displayable_path(dbpath)
-        ))
+        )%message)


This handler already catches errors when we open the database. The bug report on this thread arises after the database is already opened, when it is accessed. So I think the new exception handling bit will need to go in the main function.

Hello,
I add this in main but it gives me the message from the first UserError excpetion that raised before.

except sqlite3.OperationalError as e: if e.args[0] == "unable to open database file": raise UserError(u"unable to open database file. It might be a permissions problem")

Is there a way to do it like db_query.InvalidQueryError in order to check the mutate function in db.py?

Thank you!

Oh, cool! Looks like you're almost there. There are actually two ways to go with this:

Inside mutate, raise a UserError and let the top-level (main) exception handling print the message.

Inside main, just catch the OperationalError directly and print the error message there. (But don't raise a new UserError.)

It's actually a difficult call to say what's better, but I like your idea of raising a new, specialized exception in mutate. In fact, maybe we can invent a new error exception class, sort of like InvalidQueryError, for filesystem access problems like this one?

Hello,
I' ve tried both ways but i have the same problem. In the first way i just add in mutate raise UserError("unable to open database file. It might be a permissions problem") and in the second way i wrote in main this:

except sqlite3.OperationalError as e: if e.args[0] == "unable to open database file": print("unable to open database file. It might be a permissions problem")

I wrote also a new error exception class

class AccessFileError(Exception): """Permission Exception. Exception that Specifically inidcates the possibility of a permissions problem on database file. """

In order to work with this way i have to raise an AccessFileError in mutate and catch it in the main?

Thank you very much!

I think i fixed it and i tried it with all ways. But it works when i deny the write permission in my database file and the traceback that gives me is attempt to write a readonly database . Is this right??
Thank you

In order to work with this way i have to raise an AccessFileError in mutate and catch it in the main?

Yes, exactly!

But it works when i deny the write permission in my database file and the traceback that gives me is attempt to write a readonly database. Is this right??

It's somewhat hard to know exactly what causes specific kinds of errors in the SQLite library, which hides the precise details of what went wrong. But if you see that error when setting the database file to have permissions that prevent writing by your user, that does sound like something we should handle—perhaps in addition to the existing "unable to open database file" error?

But when it gives me the "unable to open datapase file" error it prints the message of UserError that raise the _open_library. Maybe the way i change my settings is wrong?

Thank you

Hmm… can you try pushing your updated code so it appears here in the PR? Then I can take a look at how it's actually working.

sampsyo · 2017-04-14T13:01:28Z

beets/dbcore/db.py

        cursor = self.db._connection().execute(statement, subvals)
+        raise AccessFileError("unable to open database file. It might be a permissions problem")


This should probably be in an exception handler for OperationalError.

sampsyo · 2017-04-15T15:34:17Z

beets/dbcore/db.py


    def script(self, statements):
        """Execute a string containing multiple SQL statements."""
        self.db._connection().executescript(statements)

-


I know it seems small, but we need this blank line here for consistency.

sampsyo · 2017-04-15T15:34:44Z

beets/dbcore/db.py

@@ -32,6 +32,10 @@
 from .query import MatchQuery, NullSort, TrueQuery
 import six

+class AccessFileError(Exception):


How about "DBAccessError" for clarity?

sampsyo · 2017-04-15T15:37:45Z

beets/dbcore/db.py

@@ -32,6 +32,10 @@
 from .query import MatchQuery, NullSort, TrueQuery
 import six

+class AccessFileError(Exception):
+    """UI exception. Commands should throw this in order to display
+    nonrecoverable errors to the user.


This looks like the description for UserError? Here's an alternative docstring:

The SQLite database became inaccessible. This can happen when trying to read or write the database when, for example, the database file is deleted or otherwise disappears. There is probably no way to recover from this error.

sampsyo · 2017-04-15T15:38:47Z

beets/dbcore/db.py

+            cursor = self.db._connection().execute(statement, subvals)
+            return cursor.lastrowid
+        except sqlite3.OperationalError as e:
+            raise AccessFileError("unable to open database file. It might be a permissions problem")


Here is where the check for error strings like "attempt to write a readonly database" should occur. (For what it's worth, I did a little experiment—that's the message that appears if I try to access the database after deleting the file from my disk!)

So, i have to add an if that check if e.args[0] is equals with "attempt to write a readonly database file" and another that checks if e.args[0] is equals with "unable to open database file"? I already tried it and when the message is "unable to open database file" it gives me again the message of UserError.

Thank you!

Yep! Or we can just have one if that checks whether it's either of those things:

if e.args[0] in ('string1', 'string2'):

I don't quite understand what you mean about the UserError… is some other code producing a UserError exception?

Hello,
I think i fixed it. Is it right?
Thank you!!

And re-use the SQLite error string instead of a hand-written one for now.

sampsyo · 2017-04-18T22:00:06Z

This looks great! Thank you for your contribution! I just pushed a few small changes here; let's see what Travis says.

Mary011196 · 2017-04-19T07:44:14Z

Thank you too. I will continue with the next issue. Will my code be merged?

Thank you again!

sampsyo · 2017-04-19T15:25:29Z

Looks like everything's in order. Merging now! ✨

OperationalError from SQlite that indicates a permissions problem on …

11e3a5a

…database file.

sampsyo reviewed Apr 11, 2017

View reviewed changes

Mary011196 added 3 commits April 14, 2017 09:28

adding AccessFileError as new class error excpetion

3fd04ad

handlinig AccessFileError in main

bccfcb6

Update db.py

cb2f47d

sampsyo reviewed Apr 14, 2017

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Update db.py

cf744eb

sampsyo requested changes Apr 15, 2017

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Mary011196 and others added 7 commits April 16, 2017 15:15

Change the error name to DBAccessError

f7a5844

Error check with if statemetnt

0492741

Correcting the mistakes that Travis CI showed me

e756f98

Reformat a docstring

621427f

Re-raise other errors

19e0958

And re-use the SQLite error string instead of a hand-written one for now.

Hint about database access errors

906bd97

Changelog entry for beetbox#2508

7eaaa99

sampsyo approved these changes Apr 18, 2017

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sampsyo merged commit 21c59bf into beetbox:master Apr 19, 2017

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OperationalError from SQlite that indicates a permissions problem. #2508

OperationalError from SQlite that indicates a permissions problem. #2508

Mary011196 commented Apr 11, 2017 •

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		cursor = self.db._connection().execute(statement, subvals)
		raise AccessFileError("unable to open database file. It might be a permissions problem")

OperationalError from SQlite that indicates a permissions problem. #2508

OperationalError from SQlite that indicates a permissions problem. #2508

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