lquery

Try bring C# linq to python 🎈.

The library is a demo, not for production (yet).

Compare with Others

Different between lquery and others (linq for python like asq):

lquery try convert func (from bytecode) to SQL and query on database process.

Compare with CSharp

For C#:

IQueryable<?> query = null;
var items = query.Where(z => z.Name == 's').Select(z => z.Value).ToList();

So for python:

query: Queryable = ...;
expr = query.where(lambda z: z.name == 's').select(lambda z: z.value).to_list();

for in-memory iterable

from lquery import enumerable
query: Queryable = enumerable([1, 2, 3])
# then query it

for mongodb

from lquery.extras.mongodb import MongoDbQuery
collection = # get a collection from pymongo
query: Queryable = MongoDbQuery(collection)
# then query it

linq APIs

• select
• select_many
• group_by
• where
• of_type
• take
• take_while
• skip
• skip_while
• distinct
• order_by
• order_by_descending
• reverse
• first
• first_or_default
• last
• last_or_default
• single
• single_or_default
• element_at
• count
• concat
• difference
• intersect
• union
• join
• group_join
• zip
• zip_longest
• min
• max
• sum
• average
• aggregate
• any
• all
• contains
• sequence_equal
• to_list
• to_dict
• for_each
• load - only for IQueryable, same as AsEnumerable() from C#

read more examples from unittests.

Others

print reduce info

Print reduce info is easy way to check what query will compile to SQL.

code example:

>>> from lquery.extras.mongodb import MongoDbQuery
>>> mongo_query = MongoDbQuery(None)
>>> reduce_info = mongo_query\
...     .where(lambda x: (x['size']['h'] == 14) & (x['size']['uom'] == 'cm'))\
...     .skip(1)\
...     .where(lambda x: x['size']['w'] > 15)\
...     .get_reduce_info()
>>> reduce_info.print()
reduce info of:
  Queryable()
    .where(<function <lambda> at 0x0000025DBC661EA0>)
    .skip(1)
    .where(<function <lambda> at 0x0000025DBE957840>)
=>
    [SRC] None
    [SQL] where(<function <lambda> at 0x0000025DBC661EA0>)
    [SQL] skip(1)
    [MEM] where(<function <lambda> at 0x0000025DBE957840>)

you can see the 1st where() and 1st skip() was success compile to SQL, and 2nd where() only work inside python process.