如何返回sqlite3数据库访问响应

Question

I'm new to Python. I've just created a sqlite3 db wrapper class to handle the database interaction in my application. My question is how do I return success/failure messages from my db wrapper class methods, addRow, updRow (which add and update rows) to the invoking program?

Here's the class code I cobbled together so far:-

class dbManager(object):
    def __init__(self, db):
        self.conn = lite.connect(db)
        self.conn.execute('pragma foreign_keys = on')
        self.conn.execute('pragma synchronous=off')
        self.conn.commit()
        self.cur = self.conn.cursor()

    def query(self, arg):
        self.cur.execute(arg) 
        self.conn.commit()
        return self.cur

    def addRow(self, tablename, data):
        """
        Insert data into a table. The data does not have to be escaped.
        """
        global actInserts

        # Create a new cursor
        # tc = self.conn.cursor() # opened at init 

        tablelist = ""
        valueholder = ""
        valuelist = []

        for key, value in data.items():
            if len(tablelist) > 0:
                tablelist += ', '
                valueholder += ', '

            # Add to table column list
            tablelist += key

            # Add a holder
            valueholder += '?'

            # build the insert values 
            valuelist.append(value)

        # Perform and commit the insert       
        try:
            dbResponse = self.cur.execute("INSERT INTO " + tablename + " (" + tablelist + ") VALUES (" + valueholder + ");", valuelist)
            actInserts += 1
        except lite.Error, e:
            dbResponse = 'Sqlite Error NP: ' + e.args[0] 
            print 'Sqlite Error NP: ' + e.args[0] 
        return dbResponse

    def closeConnection (self):
        self.conn.commit()
        self.conn.close() 

    def __del__(self):
        self.conn.close()

Answer 1

I think there are 2 ways you can do this. You can:

1. Change the return type of you function to something like a tuple of (error_code, SQL_results), or
2. Throw an exception if the query fails (or don't catch the one you already are handling) and leave the exception handling logic to the user (calling program).

I think option 2 is the better way.

Also, I think your query building would be more clear (or at least more concise) using something like the following (assumes that data is a dictionary)

tablelist = ','.join(list(data.viewkeys()))
valueholder = ','.join(['?' for i in data.viewkeys()])
valuelist = list(data.viewvalues())