leancloud-better-storage-python

better leancloud storage wrapper. Simple and lightweight.

Sorry for my bad grammar and spell :)

Installation

install by easy_install or pip.

pip install leancloud-better-storage

Quick start

Simple model declaration and query syntax.

Model declaration

from datetime import datetime
from leancloud_better_storage.storage.models import Model
from leancloud_better_storage.storage.fields import Field

class Product(Model):
    name = Field(nullable=False)
    price = Field(nullable=False)
    publish_at = Field()

Field constructor accept series option arguments.

• name, specify field name in database.
• nullable, should you provide initial value for this field when you create new record.
• default, if you are not set default value, commit will not create new field or set null in leancloud storage. Because undefined and null is different in javascript :( . leancloud storage based on MongoDB, and MongoDB use JavaScript as first class citizen.
• type_ not used yet.

CRUD operations

You can use Model.create to create new record, this method should check your record has been correctly initialized.

product = Product.create(name='FirstProduct', price=100)
product.commit()

# v0.1.3 now default null value
assert product.publish_at is None

If you are not pass default initial value for non-default field, it will be null (in storage, undefined).

Read & Query

use filter and/or filter_by to select records.

filter support more human readable condition selection.

• >, <, >=, <=, == compare field with some value. Not supprot compare between fields in same or not same model.
• contains simple pattern match for string field.
• and_, or_ between two or more queries.

See examples below.

# find by simple equation
products = Product.query().filter_by(name='product').find()

# support >,<,>=,<=,==.but not support compare to another field.
products = Product.query().filter(Product.price < 10).find()

# support contains
products = Product.query().filter(Product.name.contains('art')).find()

# support and_(), or_().
products = Product.query().filter(Product.created_at > datetime(2018,8,1)).and_() \
    .filter(Product.created_at < datetime(2018,9,1)).find()

# find support limit and skip argument.
products = Product.query().order_by(Product.price.desc).find(limit=10)

# support pagination, start from page 0 and 10 elements per page.
pages = Product.query().paginate(0, 10)
for page in pages:
    print(page.items) # access elements

Update

You can update record by assign new value and commit change.

product = Product.query().filter_by(name='FirstProduct').first()
product.name = 'LastProduct'
product.commit()

Delete

drop method will delete record and set object invalid. Use drop_all for bulk operation.

product = Product.query().filter_by(name='FirstProduct').first()
product.drop()

products = Product.query().filter_by().find()
Product.drop_all(products)

Known limit

Some bulk modification/deletion does not support execute with conditions. It's limited by leancloud storage service. For more detail, see document below.

• python guide - bulk operation
• CQL guide - update
• CQL guide - delete

Change log

• 0.1.7 修复初始值 null 覆盖了存储服务生成字段值的问题。