Merge pull request #161 from ryneeverett/comparison-operators

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Implement comparison operators. Resolve #128.
This commit is contained in:
Friedrich Lindenberg 2016-04-01 14:19:05 +02:00
commit 6e6a0c0500
3 changed files with 34 additions and 13 deletions
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38
dataset/persistence/table.py
View File

@ -2,6 +2,7 @@ import logging
from hashlib import sha1
from sqlalchemy.sql import and_, expression
from sqlalchemy.sql.expression import ClauseElement
from sqlalchemy.schema import Column, Index
from sqlalchemy import alias, func
from dataset.persistence.util import guess_type, normalize_column_name
@ -182,7 +183,7 @@ class Table(object):
else:
return self.insert(row, ensure=ensure, types=types)
def delete(self, **_filter):
def delete(self, *_clauses, **_filter):
""" Delete rows from the table. Keyword arguments can be used
to add column-based filters. The filter criterion will always
be equality:
@ -195,7 +196,7 @@ class Table(object):
"""
self._check_dropped()
if _filter:
q = self._args_to_clause(_filter)
q = self._args_to_clause(_filter, clauses=_clauses)
stmt = self.table.delete(q)
else:
stmt = self.table.delete()
@ -218,10 +219,10 @@ class Table(object):
_type, self.table.name))
self.create_column(column, _type)
def _args_to_clause(self, args, ensure=True):
def _args_to_clause(self, args, ensure=True, clauses=()):
if ensure:
self._ensure_columns(args)
clauses = []
clauses = list(clauses)
for k, v in args.items():
if not self._has_column(k):
clauses.append(func.sum(1) == 2)
@ -309,7 +310,7 @@ class Table(object):
self.indexes[name] = idx
return idx
def find_one(self, **kwargs):
def find_one(self, *args, **kwargs):
"""
Works just like :py:meth:`find() <dataset.Table.find>` but returns one result, or None.
::
@ -317,7 +318,7 @@ class Table(object):
row = table.find_one(country='United States')
"""
kwargs['_limit'] = 1
iterator = self.find(**kwargs)
iterator = self.find(*args, **kwargs)
try:
return next(iterator)
except StopIteration:
@ -329,8 +330,7 @@ class Table(object):
else:
return self.table.c[order_by].asc()
def find(self, _limit=None, _offset=0, _step=5000,
order_by='id', return_count=False, **_filter):
def find(self, *_clauses, **kwargs):
"""
Performs a simple search on the table. Simply pass keyword arguments as ``filter``.
::
@ -353,13 +353,20 @@ class Table(object):
For more complex queries, please use :py:meth:`db.query() <dataset.Database.query>`
instead."""
_limit = kwargs.pop('_limit', None)
_offset = kwargs.pop('_offset', 0)
_step = kwargs.pop('_step', 5000)
order_by = kwargs.pop('order_by', 'id')
return_count = kwargs.pop('return_count', False)
_filter = kwargs
self._check_dropped()
if not isinstance(order_by, (list, tuple)):
order_by = [order_by]
order_by = [o for o in order_by if (o.startswith('-') and o[1:] or o) in self.table.columns]
order_by = [self._args_to_order_by(o) for o in order_by]
args = self._args_to_clause(_filter, ensure=False)
args = self._args_to_clause(_filter, ensure=False, clauses=_clauses)
# query total number of rows first
count_query = alias(self.table.select(whereclause=args, limit=_limit, offset=_offset),
@ -380,11 +387,11 @@ class Table(object):
return ResultIter(self.database.executable.execute(query),
row_type=self.database.row_type, step=_step)
def count(self, **_filter):
def count(self, *args, **kwargs):
"""
Return the count of results for the given filter set (same filter options as with ``find()``).
"""
return self.find(return_count=True, **_filter)
return self.find(*args, return_count=True, **kwargs)
def __len__(self):
"""
@ -392,7 +399,7 @@ class Table(object):
"""
return self.count()
def distinct(self, *columns, **_filter):
def distinct(self, *args, **_filter):
"""
Returns all rows of a table, but removes rows in with duplicate values in ``columns``.
Interally this creates a `DISTINCT statement <http://www.w3schools.com/sql/sql_distinct.asp>`_.
@ -407,8 +414,13 @@ class Table(object):
"""
self._check_dropped()
qargs = []
columns = []
try:
columns = [self.table.c[c] for c in columns]
for c in args:
if isinstance(c, ClauseElement):
qargs.append(c)
else:
columns.append(self.table.c[c])
for col, val in _filter.items():
qargs.append(self.table.c[col] == val)
except KeyError:

3
docs/quickstart.rst
View File

@ -138,6 +138,9 @@ We can search for specific entries using :py:meth:`find() <dataset.Table.find>`
# Get a specific user
john = table.find_one(name='John Doe')
# Find by comparison
elderly_users = table.find(table.table.columns.age >= 70)
Using :py:meth:`distinct() <dataset.Table.distinct>` we can grab a set of rows
with unique values in one or more columns::

6
test/test_persistence.py
View File

@ -267,6 +267,8 @@ class TableTestCase(unittest.TestCase):
assert ds[0]['temperature'] == -1, ds
ds = list(self.tbl.find(order_by=['-temperature']))
assert ds[0]['temperature'] == 8, ds
ds = list(self.tbl.find(self.tbl.table.columns.temperature > 4))
assert len(ds) == 3, ds
def test_offset(self):
ds = list(self.tbl.find(place=TEST_CITY_1, _offset=1))
@ -279,6 +281,10 @@ class TableTestCase(unittest.TestCase):
assert len(x) == 2, x
x = list(self.tbl.distinct('place', 'date'))
assert len(x) == 6, x
x = list(self.tbl.distinct(
'place', 'date',
self.tbl.table.columns.date >= datetime(2011, 1, 2, 0, 0)))
assert len(x) == 4, x
def test_get_items(self):
x = list(self.tbl['place'])