pymongo操作mongo数据库的查操作

一：  数据结构

{
    "_id" : ObjectId("5de8a5b748a75a8d48b72bdc"),
    "farm_id" : "",
    "user_id" : "",
    "equipment_number" : "",
    "hybridization_detail" : [
        {
            "hybridization_time" : "2019-11-11",
            "pregnancy _time" : "2019-12-4",
            "hybridization_type" : "冻精",
            "object_type" : "奶牛",
            "sperm_count" : "",
            "sperm_number" : "",
            "hybridization_control" : "性控",
            "id" : ""
        },
        {
            "hybridization_time" : "2019-11-11",
            "pregnancy _time" : "2019-12-4",
            "hybridization_type" : "冻精",
            "object_type" : "奶牛",
            "sperm_count" : "",
            "sperm_number" : "",
            "hybridization_control" : "性控",
            "id" : ""
        }
    ]
}

1. 普通查询  查询farm_id = 2的信息

find_one 返回的是一个字典类型的数据

from pymongo import MongoClient
import logging
lg = logging.getLogger("info")
lg.setLevel(logging.DEBUG)class Mongodb_Wrapper(object):
    database_name = "test_function"
    collection_name = "normal"
    host = "127.0.0.1"
    port = 27017
    def __init__(self):
        self.client = MongoClient(host=self.host,port=self.port)
        self.db = self.client[self.database_name][self.collection_name]    def find_one(self):
        ret = self.db.find_one({"farm_id":""})
        return retm = Mongodb_Wrapper()
ret = m.find_one()
print(ret)
print(type(ret))# 结果{'_id': ObjectId('5de8a5b748a75a8d48b72bdc'), 'farm_id': '', 'user_id': '', 'equipment_number': '', 'hybridization_detail': [{'hybridization_time': '2019-11-11', 'pregnancy _time': '2019-12-4', 'hybridization_type': '冻精', 'object_type': '奶牛', 'sperm_count': '', 'sperm_number': '', 'hybridization_control': '性控', 'id': ''}, {'hybridization_time': '2019-11-11', 'pregnancy _time': '2019-12-4', 'hybridization_type': '冻精', 'object_type': '奶牛', 'sperm_count': '', 'sperm_number': '', 'hybridization_control': '性控', 'id': ''}]}
<class 'dict'>

不想显示_id和farm_id怎么办？可以增加第二个参数，过滤条件

 def find_one(self):
        ret = self.db.find_one({"farm_id":""},{"_id":0,"farm_id":0})
        return ret结果：
{'user_id': '', 'equipment_number': '', 'hybridization_detail': [{'hybridization_time': '2019-11-11', 'pregnancy _time': '2019-12-4', 'hybridization_type': '冻精', 'object_type': '奶牛', 'sperm_count': '', 'sperm_number': '', 'hybridization_control': '性控', 'id': ''}, {'hybridization_time': '2019-11-11', 'pregnancy _time': '2019-12-4', 'hybridization_type': '冻精', 'object_type': '奶牛', 'sperm_count': '', 'sperm_number': '', 'hybridization_control': '性控', 'id': ''}]}
<class 'dict'>

根据列表里面的字段进行查询

只想显示 “id” : “15755278639220782”的这条数据怎么办，通过限制 hybridization_detail的值进行查询，$elemMatch进行操作

情况一：唯一值字段 id

def find_one(self):
    ret = self.db.find_one({"hybridization_detail.id":""},{"hybridization_detail":{"$elemMatch":{"id":""}}})
    return ret# 结果{'_id': ObjectId('5de8a5b748a75a8d48b72bdc'), 'hybridization_detail': [{'hybridization_time': '2019-11-11', 'pregnancy _time': '2019-12-4', 'hybridization_type': '冻精', 'object_type': '奶牛', 'sperm_count': '', 'sperm_number': '', 'hybridization_control': '性控', 'id': ''}]}
<class 'dict'>

但是不想显示_id字段，增加过滤条件

def find_one(self):
    ret = self.db.find_one({"hybridization_detail.id":""},{"_id":0},{"hybridization_detail":{"$elemMatch":{"id":""}}})
    return ret# 结果：TypeError: skip must be an instance of int

情况二：不唯一值字段 id以外的所有字段：只显示匹配到的第一个字段，因此要保证数据的唯一性，就增加有唯一值的字段。

def find_one(self):
    ret = self.db.find_one({"hybridization_detail.sperm_count":""},{"hybridization_detail":{"$elemMatch":{"sperm_count":""}}})
    return ret#结果：只显示匹配到的第一个数据
{'_id': ObjectId('5de8a5b748a75a8d48b72bdc'), 'hybridization_detail': [{'hybridization_time': '2019-11-11', 'pregnancy _time': '2019-12-4', 'hybridization_type': '冻精', 'object_type': '奶牛', 'sperm_count': '', 'sperm_number': '', 'hybridization_control': '性控', 'id': ''}]}
<class 'dict'>

修改数据结构为

{
    "_id" : ObjectId("5de8a5b748a75a8d48b72bdc"),
    "farm_id" : "",
    "user_id" : "",
    "equipment_number" : "",
    "hybridization_detail" : [
        {
            "hybridization_time" : "2019-11-11",
            "pregnancy _time" : "2019-12-4",
            "hybridization_type" : "冻精",
            "object_type" : "奶牛",
            "sperm_count" : "",
            "sperm_number" : "",
            "hybridization_control" : "性控",
            "id" : ""
        },
        {
            "hybridization_time" : "2019-11-12",
            "pregnancy _time" : "2019-12-5",
            "hybridization_type" : "冻精",
            "object_type" : "奶牛",
            "sperm_count" : "",
            "sperm_number" : "",
            "hybridization_control" : "性控",
            "id" : ""
        },
        {
            "hybridization_time" : "2019-11-13",
            "pregnancy _time" : "2019-12-6",
            "hybridization_type" : "冻精",
            "object_type" : "奶牛",
            "sperm_count" : "",
            "sperm_number" : "",
            "hybridization_control" : "性控",
            "id" : ""
        },
        {
            "hybridization_time" : "2019-11-14",
            "pregnancy _time" : "2019-12-7",
            "hybridization_type" : "冻精",
            "object_type" : "奶牛",
            "sperm_count" : "",
            "sperm_number" : "",
            "hybridization_control" : "性控",
            "id" : ""
        }
    ]
}

查询  “hybridization_time” 的时间从2019-11-11到2019-11-13的数据

# TODO