Django多数据库联用实现方法解析

# Database
# https://docs.djangoproject.com/en/1.8/ref/settings/#databases
DATABASES = {
  'default': {
    'ENGINE': 'django.db.backends.sqlite3',
    'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
  },
  'db1': {
    'ENGINE': 'django.db.backends.mysql',
    'NAME': 'dbname1',
    'USER': 'your_db_user_name',
    'PASSWORD': 'yourpassword',
    "HOST": "localhost",
  },
  'db2': {
    'ENGINE': 'django.db.backends.mysql',
    'NAME': 'dbname2',
    'USER': 'your_db_user_name',
    'PASSWORD': 'yourpassword',
    "HOST": "localhost",
  },
}
 
# use multi-database in django
# add by WeizhongTu
DATABASE_ROUTERS = ['project_name.database_router.DatabaseAppsRouter']
DATABASE_APPS_MAPPING = {
  # example:
  #'app_name':'database_name',
  'app1': 'db1',
  'app2': 'db2',
}

# -*- coding: utf-8 -*-
from django.conf import settings
 
DATABASE_MAPPING = settings.DATABASE_APPS_MAPPING
 
 
class DatabaseAppsRouter(object):
  """
  A router to control all database operations on models for different
  databases.
 
  In case an app is not set in settings.DATABASE_APPS_MAPPING, the router
  will fallback to the `default` database.
 
  Settings example:
 
  DATABASE_APPS_MAPPING = {'app1': 'db1', 'app2': 'db2'}
  """
 
  def db_for_read(self, model, **hints):
    """"Point all read operations to the specific database."""
    if model._meta.app_label in DATABASE_MAPPING:
      return DATABASE_MAPPING[model._meta.app_label]
    return None
 
  def db_for_write(self, model, **hints):
    """Point all write operations to the specific database."""
    if model._meta.app_label in DATABASE_MAPPING:
      return DATABASE_MAPPING[model._meta.app_label]
    return None
 
  def allow_relation(self, obj1, obj2, **hints):
    """Allow any relation between apps that use the same database."""
    db_obj1 = DATABASE_MAPPING.get(obj1._meta.app_label)
    db_obj2 = DATABASE_MAPPING.get(obj2._meta.app_label)
    if db_obj1 and db_obj2:
      if db_obj1 == db_obj2:
        return True
      else:
        return False
    return None
 
  # for Django 1.4 - Django 1.6
  def allow_syncdb(self, db, model):
    """Make sure that apps only appear in the related database."""
 
    if db in DATABASE_MAPPING.values():
      return DATABASE_MAPPING.get(model._meta.app_label) == db
    elif model._meta.app_label in DATABASE_MAPPING:
      return False
    return None
 
  # Django 1.7 - Django 1.11
  def allow_migrate(self, db, app_label, model_name=None, **hints):
    print db, app_label, model_name, hints
    if db in DATABASE_MAPPING.values():
      return DATABASE_MAPPING.get(app_label) == db
    elif app_label in DATABASE_MAPPING:
      return False
    return None