Sqlite and Python -- return a dictionary using fetchone()?

Question

I'm using sqlite3 in python 2.5. I've created a table that looks like this:

   create table votes (
      bill text,
      senator_id text,
      vote text)

I'm accessing it with something like this:

v_cur.execute("select * from votes")
row = v_cur.fetchone()
bill = row[0]
senator_id = row[1]
vote = row[2]

What I'd like to be able to do is have fetchone (or some other method) return a dictionary, rather than a list, so that I can refer to the field by name rather than position. For example:

bill = row['bill'] 
senator_id = row['senator_id']
vote = row['vote']

I know you can do this with MySQL, but does anyone know how to do it with SQLite?

Thanks!!!

Answer 1

There is actually an option for this in sqlite3. Change the row_factory member of the connection object to sqlite3.Row:

conn = sqlite3.connect('db', row_factory=sqlite3.Row)

or

conn.row_factory = sqlite3.Row

This will allow you to access row elements by name--dictionary-style--or by index. This is much more efficient than creating your own work-around.

Answer 2

The way I've done this in the past:

def dict_factory(cursor, row):
    d = {}
    for idx,col in enumerate(cursor.description):
        d[col[0]] = row[idx]
    return d

Then you set it up in your connection:

from pysqlite2 import dbapi2 as sqlite
conn = sqlite.connect(...)
conn.row_factory = dict_factory

This works under pysqlite-2.4.1 and python 2.5.4.

Answer 3

I was recently trying to do something similar while using sqlite3.Row(). While sqlite3.Row() is great for providing a dictionary-like interface or a tuple like interface, it didn't work when I piped in the row using **kwargs. So, needed a quick way of converting it to a dictionary. I realised that the Row() object can be converted to a dictionary simply by using itertools.

Python 2:

db.row_factory = sqlite3.Row
dbCursor = db.cursor()
dbCursor.execute("SELECT * FROM table")
row = dbCursor.fetchone()

rowDict = dict(itertools.izip(row.keys(), row))

Or in Python 3, more simply:

dbCursor = db.cursor()
dbCursor.execute("SELECT * FROM table")
row = dbCursor.fetchone()
rowDict = dict(zip([c[0] for c in dbCursor.description], row))

Similarly, you can use the dbCursor.fetchall() command and convert the entire set of rows to a list of dictionaries in a for loop.

Answer 4

Sure, make yourself a DictConnection and DictCursor as explained and shown at http://trac.edgewall.org/pysqlite.org-mirror/wiki/PysqliteFactories for example.

Answer 5

I know you're not asking this, but why not just use sqlalchemy to build an orm for the database? then you can do things like,

entry = model.Session.query(model.Votes).first()
print entry.bill, entry.senator_id, entry.vote

as an added bonus your code will be easily portable to an alternative database, and connections and whatnot will be managed for free.

Answer 6

I've used this:

def get_dict(sql):
    return dict(c.execute(sql,()).fetchall())

Then you can do this:

c = conn.cursor()
d = get_dict("select user,city from vals where user like 'a%'");

Now d is a dictionary where the keys are user and the values are city. This also works for group by

Answer 7

Simple solution, initialize a cursor object:

cursor = conn.cursor(buffered = True, dictionary = True)

Another option:

cursor = conn.cursor(MySQLdb.cursors.DictCursor)

Rest of Code:

query = "SELECT * FROM table"
cursor.execute(query)
row = cursor.fetchone()

Sources: mysql.connector.cursor , MySQLdb.cursors.DictCursor

Answer 8

I use something like this:

class SqliteRow(object):
    def __init__(self):
        self.fields = []

    def add_field(self, name, value):
        self.fields.append(name)
        setattr(self, name, value)

    def to_tuple(self):
        return tuple([getattr(self, x) for x in self.fields])

with this:

def myobject_factory(cursor, row):
    myobject= MyObject()
    for idx, col in enumerate(cursor.description):
        name, value = (col[0], row[idx])

        myobject.add_field(name, value)
    return myobject

MyObject() is a class that inherits from SqliteRow. SqliteRow class is a base class for every object that I want to have returned by a query. Every column becomes an attribute and is logged into the fields list. Function to_tuple is used to change the whole object to a form suitable for queries (simply pass the whole object and forget).

To get different class types of that function. You would need to make a factory object, that will generate objects based on the list of fields (for example: dict with { some_unique_value_made_of_fields: class} )

This way I get a simple ORM.