lquery 0.1.1

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Try bring C# linq to python 馃巿.

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 from 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 = None;
expr = query.where(z => z.name == 's').select(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

• to_memory - same as AsEnumerable() from C#

• where

• select

• select_many

• take

• skip

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>)
=>
    [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.