• Python操作MongoDB文档数据库


    1.Pymongo 安装

    安装pymongo:
    
    pip install pymongo
    • PyMongo是驱动程序,使python程序能够使用Mongodb数据库,使用python编写而成;

    2.Pymongo 方法

    • insert_one():插入一条记录;
    • insert():插入多条记录;
    • find_one():查询一条记录,不带任何参数返回第一条记录,带参数则按条件查找返回;
    • find():查询多条记录,不带参数返回所有记录,带参数按条件查找返回;
    • count():查看记录总数;
    • create_index():创建索引;
    • update_one():更新匹配到的第一条数据;
    • update():更新匹配到的所有数据;
    • remove():删除记录,不带参表示删除全部记录,带参则表示按条件删除;
    • delete_one():删除单条记录;
    • delete_many():删除多条记录;

    3.Pymongo 中的操作

    • 查看数据库
    from pymongo import MongoClient
    
    connect = MongoClient(host='localhost', port=27017, username="root", password="123456")
    connect = MongoClient('mongodb://localhost:27017/', username="root", password="123456")
    
    print(connect.list_database_names())
    • 获取数据库实例
    test_db = connect['test']
    • 获取collection实例
    collection = test_db['students']
    • 插入一行document, 查询一行document,取出一行document的值
    from pymongo import MongoClient
    from datetime import datetime
    
    connect = MongoClient(host='localhost', port=27017, username="root", password="123456",)
    # 获取db
    test_db = connect['test']
    # 获取collection
    collection = test_db['students']
    # 构建document
    document = {"author": "Mike",  "text": "My first blog post!", "tags": ["mongodb", "python", "pymongo"], "date": datetime.now()}
    # 插入document
    one_insert = collection.insert_one(document=document)
    print(one_insert.inserted_id)
    
    # 通过条件过滤出一条document
    one_result = collection.find_one({"author": "Mike"})
    # 解析document字段
    print(one_result, type(one_result))
    print(one_result['_id'])
    print(one_result['author'])
    
    注意:如果需要通过id查询一行document,需要将id包装为ObjectId类的实例对象
    from bson.objectid import ObjectId
    collection.find_one({'_id': ObjectId('5c2b18dedea5818bbd73b94c')})
    • 插入多行documents, 查询多行document, 查看collections有多少行document
    from pymongo import MongoClient
    from datetime import datetime
    connect = MongoClient(host='localhost', port=27017, username="root", password="123456",)
    
    # 获取db
    test_db = connect['test']
    
    # 获取collection
    collection = test_db['students']
    documents = [{"author": "Mike","text": "Another post!","tags": ["bulk", "insert"], "date": datetime(2009, 11, 12, 11, 14)},
    {"author": "Eliot", "title": "MongoDB is fun", "text": "and pretty easy too!", "date": datetime(2009, 11, 10, 10, 45)}]
    collection.insert_many(documents=documents)
    
    # 通过条件过滤出多条document
    documents = collection.find({"author": "Mike"})
    
    # 解析document字段
    print(documents, type(documents))
    print('*'*300)
    for document in documents:
        print(document)
    print('*'*300)
    result = collection.count_documents({'author': 'Mike'})
    print(result)
    • 范围比较查询
    from pymongo import MongoClient
    from datetime import datetime
    
    connect = MongoClient(host='localhost', port=27017, username="root", password="123456",)
    
    # 获取db
    test_db = connect['test']
    
    # 获取collection
    collection = test_db['students']
    
    # 通过条件过滤时间小于datetime(2019, 1,1,15,40,3) 的document
    documents = collection.find({"date": {"$lt": datetime(2019, 1,1,15,40,3)}}).sort('date')
    
    # 解析document字段
    print(documents, type(documents))
    print('*'*300)
    for document in documents:
        print(document)
    • 创建索引
    from pymongo import MongoClient
    import pymongo
    from datetime import datetime
    
    connect = MongoClient(host='localhost', port=27017, username="root", password="123456",)
    # 获取db
    test_db = connect['test']
    # 获取collection
    collection = test_db['students']
    # 创建字段索引
    collection.create_index(keys=[("name", pymongo.DESCENDING)], unique=True)
    # 查询索引
    result = sorted(list(collection.index_information()))
    print(result)
    • document修改
    from pymongo import MongoClient
    connect = MongoClient(host='localhost', port=27017, username="root", password="123456",)
    
    # 获取db
    test_db = connect['test']
    
    # 获取collection
    collection = test_db['students']
    result = collection.update({'name': 'robby'}, {'$set': {"name": "Petter"}})
    print(result)
    注意:还有update_many()方法
    • document删除
    from pymongo import MongoClient
    connect = MongoClient(host='localhost', port=27017, username="root", password="123456",)
    
    # 获取db
    test_db = connect['test']
    
    # 获取collection
    collection = test_db['students']
    result = collection.delete_one({'name': 'Petter'})
    print(result.deleted_count)
    注意:还有delete_many()方法

    4.MongoDB ODM 详解

    • MongoDB ODM 与 Django ORM使用方法类似;
    • MongoEngine是一个对象文档映射器,用Python编写,用于处理MongoDB;
    • MongoEngine提供的抽象是基于类的,创建的所有模型都是类;
    # 安装mongoengine
    pip install mongoengine
    • mongoengine使用的字段类型
    BinaryField
    BooleanField
    ComplexDateTimeField
    DateTimeField
    DecimalField
    DictField
    DynamicField
    EmailField
    EmbeddedDocumentField
    EmbeddedDocumentListField
    FileField
    FloatField
    GenericEmbeddedDocumentField
    GenericReferenceField
    GenericLazyReferenceField
    GeoPointField
    ImageField
    IntField
    ListField:可以将自定义的文档类型嵌套
    MapField
    ObjectIdField
    ReferenceField
    LazyReferenceField
    SequenceField
    SortedListField
    StringField
    URLField
    UUIDField
    PointField
    LineStringField
    PolygonField
    MultiPointField
    MultiLineStringField
    MultiPolygonField

    5.使用mongoengine创建数据库连接

    from mongoengine import connect
    
    conn = connect(db='test', host='localhost', port=27017, username='root', password='123456', authentication_source='admin')
    print(conn)

    connect(db = None,alias ='default',** kwargs );

    • db:要使用的数据库的名称,以便与connect兼容;
    • host :要连接的mongod实例的主机名;
    • port :运行mongod实例的端口;
    • username:用于进行身份验证的用户名;
    • password:用于进行身份验证的密码;
    • authentication_source :要进行身份验证的数据库;

    构建文档模型,插入数据

    from mongoengine import connect, 
                            Document, 
                            StringField,
                            IntField, 
                            FloatField,
                            ListField, 
                            EmbeddedDocumentField,
                            DateTimeField, 
                            EmbeddedDocument
    from datetime import datetime
    
    # 嵌套文档
    class Score(EmbeddedDocument):
        name = StringField(max_length=50, required=True)
        value = FloatField(required=True)
    
    class Students(Document):
        choice =  (('F', 'female'),
                   ('M', 'male'),)
        name = StringField(max_length=100, required=True, unique=True)
        age = IntField(required=True)
        hobby = StringField(max_length=100, required=True, )
        gender = StringField(choices=choice, required=True)
        # 这里使用到了嵌套文档,这个列表中的每一个元素都是一个字典,因此使用嵌套类型的字段
        score = ListField(EmbeddedDocumentField(Score))
        time = DateTimeField(default=datetime.now())
    
    if __name__ == '__main__':
        connect(db='test', host='localhost', port=27017, username='root', password='123456', authentication_source='admin')
        math_score = Score(name='math', value=94)
        chinese_score = Score(name='chinese', value=100)
        python_score = Score(name='python', value=99)
    
        for i in range(10):
            students = Students(name='robby{}'.format(i), age=int('{}'.format(i)), hobby='read', gender='M', score=[math_score, chinese_score, python_score])
            students.save()

    查询数据

    from mongoengine import connect, 
                            Document, 
                            StringField,
                            IntField, 
                            FloatField,
                            ListField, 
                            EmbeddedDocumentField,
                            DateTimeField, 
                            EmbeddedDocument
    from datetime import datetime
    
    # 嵌套文档
    class Score(EmbeddedDocument):
        name = StringField(max_length=50, required=True)
        value = FloatField(required=True)
    
    class Students(Document):
        choice =  (('F', 'female'),
                   ('M', 'male'),)
    
        name = StringField(max_length=100, required=True, unique=True)
        age = IntField(required=True)
        hobby = StringField(max_length=100, required=True, )
        gender = StringField(choices=choice, required=True)
        # 这里使用到了嵌套文档,这个列表中的每一个元素都是一个字典,因此使用嵌套类型的字段
        score = ListField(EmbeddedDocumentField(Score))
        time = DateTimeField(default=datetime.now())
    
    if __name__ == '__main__':
        connect(db='test', host='localhost', port=27017, username='root', password='123456', authentication_source='admin')
    
        first_document = Students.objects.first()
    
        all_document = Students.objects.all()
    
        # 如果只有一条,也可以使用get
        specific_document = Students.objects.filter(name='robby3')
    
        print(first_document.name, first_document.age, first_document.time)
    
        for document in all_document:
            print(document.name)
    
        for document in specific_document:
            print(document.name, document.age)

    修改、更新、删除数据

    from mongoengine import connect, 
                            Document, 
                            StringField,
                            IntField, 
                            FloatField,
                            ListField, 
                            EmbeddedDocumentField,
                            DateTimeField, 
                            EmbeddedDocument
    from datetime import datetime
    
    # 嵌套文档
    class Score(EmbeddedDocument):
        name = StringField(max_length=50, required=True)
        value = FloatField(required=True)
    
    class Students(Document):
        choice =  (('F', 'female'),
                   ('M', 'male'),)
    
        name = StringField(max_length=100, required=True, unique=True)
        age = IntField(required=True)
        hobby = StringField(max_length=100, required=True, )
        gender = StringField(choices=choice, required=True)
        # 这里使用到了嵌套文档,这个列表中的每一个元素都是一个字典,因此使用嵌套类型的字段
        score = ListField(EmbeddedDocumentField(Score))
        time = DateTimeField(default=datetime.now())
    
    if __name__ == '__main__':
        connect(db='test', host='localhost', port=27017, username='root', password='123456', authentication_source='admin')
    
        specific_document = Students.objects.filter(name='robby3')
        specific_document.update(set__age=100)
        specific_document.update_one(set__age=100)
    
        for document in specific_document:
            document.name = 'ROBBY100'
            document.save()
    
        for document in specific_document:
            document.delete()
    • all():返回所有文档;
    • all_fields():包括所有字段;
    • as_pymongo():返回的不是Document实例 而是pymongo值;
    • average():平均值超过指定字段的值;
    • batch_size():限制单个批次中返回的文档数量;
    • clone():创建当前查询集的副本;
    • comment():在查询中添加注释;
    • count():计算查询中的选定元素;
    • create():创建新对象,返回保存的对象实例;
    • delete():删除查询匹配的文档;
    • distinct():返回给定字段的不同值列表;

    嵌入式文档查询的方法

    • count():列表中嵌入文档的数量,列表的长度;
    • create():创建新的嵌入式文档并将其保存到数据库中;
    • delete():从数据库中删除嵌入的文档;
    • exclude(** kwargs ):通过使用给定的关键字参数排除嵌入的文档来过滤列表;
    • first():返回列表中的第一个嵌入文档;
    • get():检索由给定关键字参数确定的嵌入文档;
    • save():保存祖先文档;
    • update():使用给定的替换值更新嵌入的文档;
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  • 原文地址:https://www.cnblogs.com/wefeng/p/11503102.html
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