DB link 工具

Published:

Django 是个便于新人上手的 web 项目,内置简单的 Django-ORM ,但却无法很好的对已存在的数据库进行链接,功能强大的 Sqlalchemy 又不面向新手,故小造轮子,以便的对已存在的表增删该查,其中查询语法类似 Django ORM,同时加入了方便的 join 操作。该工具支持批量操作。

功能简介

假设使用如下语法创建了两张表: usersaddresses

CREATE TABLE users (
    id INTEGER NOT NULL,
    name VARCHAR(50),
    fullname VARCHAR(50),
    password VARCHAR(12),
    PRIMARY KEY (id)
);

CREATE TABLE addresses (
    id INTEGER NOT NULL,
    email_address VARCHAR NOT NULL,
    user_id INTEGER,
    PRIMARY KEY (id),
    FOREIGN KEY(user_id) REFERENCES users (id)
);

你可以使用支持的 Database Urls 对已存在于数据库中的表进行链接并作出相应操作。

from dblink import Database, Table
db = Database(url='sqlite:///:memory:')
user_table = Table('users', db)
# ...
db.close()

with Database(url='postgresql://scott:tiger@localhost/mydatabase') as db:
    address_table = Table('addresses', db)
    # ...

下面是一个简单的操作示例:

"""
Suppose you have two table: users and addresses.
"""
from dblink import Database, Table


with Database('sqlite:///:memory:') as db:
    table_user = Table('users', db)
    table_address = Table('addresses', db)

    # show description
    print(table_user.description)
    print(table_address.description)

    # chain query, you can call delete on the single table result
    table_user.query.filter(id=1).one_or_none()

    table_user.query.filter(id__gte=2) \
                    .order_by('name') \
                    .values_list('id', 'name')

    table_user.query.filter(id__in=[1, 2, 3]) \
                    .filter(name__startswith='Yu').all()

    table_user.query.order_by('-name') \
                    .values_list('fullname', flat=True, distinct=True)

    table_user.query.distinct('name').values_list('name', flat=True)

    table_user.query.filter(id__in=[1, 2, 3]).delete()

    # join query
    table_user.join(table_address) \
              .filter(id__lt=10000) \
              .filter(email_address__contains='gmail') \
              .filter(**{'addresses.id__gte': 100}) \
              .values_list('user_id', 'name', 'email_address',
                           table_address.id, 'users.fullname')

    # get or insert
    instance, create = table_user.get_or_insert(id=1, name='jone')

    # single record operation.
    table_user.insert({'id': 1, 'name': 'YuJun', 'password': 'psw'})

    table_user.update({'id': 1, 'name': 'skyduy', 'password': 'psw'},
                      unique_fields=['id'], update_fields=['name', 'password'])

    table_user.insert_or_update(
        {'id': 1, 'name': 'skyduy', 'password': 'psw'},
        unique_fields=['id'], update_fields=['name', 'password']
    )

    table_user.delete({'id': 1, 'name': "I don't matter"},
                      unique_fields=['id'])

    # bulk operation
    items = [{'id': 1, 'name': 'yujun', 'password': 'haha'},
             {'id': 2, 'name': 'skyduy', 'password': 'aha'},]
    unique_fields = ['id']
    update_fields = ['name']
    table_user.bulk_insert(items)
    table_user.bulk_delete(items, unique_fields)
    table_user.bulk_update(items, unique_fields, update_fields)
    table_user.bulk_insert_or_update(items, unique_fields, update_fields)

安装和源码

  • 直接使用 pip 安装: pip install dblink
  • 源码请戳这里