MongoDB连接

# python use mongoengine -- pip3 install mongoengine
import mongoengine
mongoengine.connect(host="mongodb://172.16.34.82:27017/test")
# or connect with keywords
mongoengine.connect("test", host="172.16.34.82", port=27017)
# if should use auth
mongoengine.connect(host="mongodb://my_user:my_password@hostname:port/my_db?authSource=admin")
# or with keywords
mongoengine.connect('my_db', username='my_user', password='my_password', authentication_source='admin')
# provide a alias name when connect
mongoengine.connect(alias="db1", db="test")
# disconnect
mongoengine.disconnect()
# disconnect a particular connection
mongoengine,disconnect(alias="test")

// use mongosh -- apt install mongodb-mongosh
// connect to local server
mongosh "mongodb://localhost:27017"
mongosh --port 28015
// connect to remmote deployment
mongosh --host mongodb0.example.com --port 28015
mongosh "mongodb://mongodb0.example.com:28015"
//disconnect
exit

# python
import mongoengine
mongoengine.connect(db="sit", alias="sit", host="172.16.34.82", port=27017)
mongoengine.connect(db="test", alias="test", host="172.16.34.82", port=27017)
class SIT(mongoengine.Document):
    name = mongoengine.StringField()
    meta = {'db_alias': "sit"}
    
class TEST(mongoengine.Document):
    name = mongoengine.StringField()
    meta = {'db_alias': "test"}


from mongoengine import context_managers
# Make sure any aliases have been registered with register_connection() or connect() 
# before using the context manager.
mongoengine.connect(db="result", alias="result", host="172.16.34.82", port=27017)
with context_managers.switch_db(TEST, "result") as TEST:
  	TEST(name='ROSS').save() # saves the "result"

// mongosh
// get all dbs
show dbs
// switch to sit db
use sit

# python
from mongoengine import context_managers

# 指定集合
class Page(Document):
    title = StringField(max_length=200, required=True)
    meta = {'collection': 'cmsPage'}

# 切换集合
with context_managers.switch_collection(TEST, "result") as TEST:
  	TEST(name='ROSS').save() # saves the "result"
    
# 固定集合（Capped Collection）
class Log(Document):
    ip_address = StringField()
    meta = {'max_documents': 1000, 'max_size': 2000000}

import mongoengine as mg
import datetime

# 连接数据库，创建数据库别名
mg.connect(db="test", alias="test", host="172.16.34.82", port=27017)

# 定义文档模式，定义字段和所属数据库
class Page(mg.Document):
    # 默认情况下，定义的字段不是必填，可以通过设置`required=True`将该字段设置为必填
    title = mg.StringField(max_length=200, required=True)
    # 字段也可以采用默认值，如果未提供值，将使用默认值
    date = mg.DateTimeField(default=datetime.datetime.utcnow())
    meta = {'db_alias': "test"}

# 实例化一个文档
page = Page(title="first documents")

# 指定插入的集合，插入文档
from mongoengine import context_managers
with context_managers.switch_collection(Page, "result"):
    page.save()

test> db.result.find()
[
  {
    _id: ObjectId("63fdeb239f17ff42a578fda0"),
    title: 'first documents',
    date: ISODate("2023-02-28T11:51:46.763Z")
  }
]

class Page(Document):
    category = IntField()
    title = StringField()
    rating = StringField()
    created = DateTimeField()
    meta = {
        'indexes': [
          	# may either be a single field name, a tuple containing multiple field names, or a dictionary containing a full index definition.
            'title',   # single-field index
            '$title',  # text index
            '#title',  # hashed index
            ('title', '-rating'),  # compound index
            ('category', '_cls'),  # compound index
            {
                'fields': ['created'],
                'expireAfterSeconds': 3600  # ttl index
            }
        ]
    }

class Session(Document):
    created = DateTimeField(default=datetime.utcnow)
    meta = {
        'indexes': [
            {'fields': ['created'], 'expireAfterSeconds': 3600}
        ]
    }

class BlogPost(Document):
    title = StringField()
    published_date = DateTimeField()

    meta = {
        'ordering': ['-published_date']
    }

# Stored in a collection named 'page'
class Page(Document):
    title = StringField(max_length=200, required=True)

    meta = {'allow_inheritance': True}

# Also stored in the collection named 'page'
class DatedPage(Page):
    date = DateTimeField()
    
Page(title='a funky title').save()
DatedPage(title='another title', date=datetime.utcnow()).save()

print(Page.objects().count())         # 2
print(DatedPage.objects().count())    # 1

class BaseDocument(Document):
    meta = {
        'abstract': True,
    }
    def check_permissions(self):
        ...

class User(BaseDocument):
   ...