MongoDB aggregate 使用

MongoDB aggregate 使用

mod 整除的使用

https://docs.mongodb.com/manual/reference/operator/aggregation/mod/

limit 使用

https://docs.mongodb.com/manual/reference/operator/aggregation/limit/

skip 使用

https://docs.mongodb.com/manual/reference/operator/aggregation/skip/

sort 使用

https://docs.mongodb.com/manual/reference/operator/aggregation/sort/

match 顧慮

https://docs.mongodb.com/manual/reference/operator/aggregation/match/

project 輸出指定字段

https://docs.mongodb.com/manual/reference/operator/aggregation/project/

example

from pymongo import MongoClient

# 多線程在實例化MongoClient時，要加上connect = False, pymongo不是進程安全的
mongo1 = MongoClient(MONGODB_CONFIG["anthcraft"], connect=False)
anthcraft = mongo1["anthcraft"]

    fields = {
        'title': 1,
        'is_free': 1,
        'thumbnail': 1,
        'layer1': 1,
        'layer2': 1,
        'layer3': 1,
        'createTime': 1,
        'updateTime': 1,
    }
    cond = {'apkType': apkType, 'status': 1}
    number = 3
    skip = 10
    pageSize = 20
    
    table = anthcraft.wallpaper_4d
    
    
    fields_tmp = fields.copy()
    #order
    fields_tmp['num1'] = {'$floor': {'$divide': ['$order', 1000]}}
    #id
    fields_tmp['num2'] = {'$mod':
        [
            {'$add': ['$_id', number]},
            number * 10
        ]
    }
    #updateTime
    fields_tmp['num3'] = '$updateTime'

    pipeline = [
        {'$match': cond},
        {'$project': fields_tmp},
        {'$sort': {'num3': 1, 'num2': 1, 'num1': 1}},
        {'$skip': skip},
        {'$limit': pageSize},
        {'$project': fields},
    ]
    rs = table.aggregate(pipeline)
    

注意：

• 對於sort 的使用，排序字段的順序是按着key字符串排序的

• 之所以用num3、num2、num1 就是爲了排序按指定的順序