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Database agnostic query system

Project description

link.dbrequest is a database agnostic query system.

See documentation for more informations.

License Development Status Latest release Supported Python versions Supported Python implementations Download format Build status Code test coverage Downloads Code Health


pip install link.dbrequest


  • database agnostic
  • lazy query resolving
  • cached queries
  • queries are unique


Getting a backend:

from link.middleware.core import Middleware

# Will open a QueryManager using a MongoDB backend
manager = Middleware.get_middleware_by_uri('query+mongo://localhost:27107/mydatabase/mycollection')
# Will open a QueryManager using a SQL backend
manager = Middleware.get_middleware_by_uri('query+sql://localhost:5432/mydatabase/mytable')

Operations on the backend:

from link.dbrequest.expression import E, F
from link.dbrequest.assignment import A
from link.dbrequest.comparison import C

query = manager.all()  # get an iterable over all elements

manager.create(A('foo', 'bar'))  # put document {'foo': 'bar'} into database

doc = manager.get(C('foo') != 'bar')  # get single element, or None

Operations on queries:

docs = list(query)  # iterate over query to execute the request
docs = list(query)  # use cache when iterating again

# create a new query from the first one
q2 = query.filter(C('foo') == 'bar')
assert query is not q2

# exclude documents without a field named "bar"
q3 = q2.exclude(~C('bar'))

# filter documents "weight > 5" and "prop1 < prop2 * 5"
q4 = q3.filter((C('weight') > 5) & (C('prop1') < (E('prop2') * 5)))

# set "prop3 = prop1 + prop2" on q2 result
docs = q2.update(A('prop3', E('prop1') + E('prop2')))

# delete documents

Operations on documents:

# save/delete a single document


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