Question

以下在mongodb shell中直接输入时有效 - 我收到正确的输出：

db.serial_key.find({key: {$ne : "5SNT0V"}})

然而，在Python 3中，它不起作用。每次只有if块运行。如果我在查询中使用str，则无关紧要。

    for x in keys:
         i +=1;
         print('key %d  = ' %i ,  keys[i-1])  #out put: key 1  =  3ZOHSH

         # place values in dictionary
         keyrecord_record = {'key':keys[i-1],'b_p_code':x1}


         if(db.serial_key.find({'key':{ '$ne':str(keys[i-1])}})):
             db.insert(keyrecord_record)
         else:
             print('Record in DB')

拜托，我希望得到一些专家的帮助。我试图在一天之内做到这一点。我只想写出数据库中尚未存在的值。

我发现了这个问题： Mongo db not equal to query not working

......但它没有回答我的问题。

===================完整的主类代码======================== ==

from pymongo import MongoClient
from algo import algo


#take in put data
x1 = int(input("Enter a number(Brand_name+Pack_size) : "))
y1 = int(input("Enter a number: key Quntity "))

#create connection
client = MongoClient()

#create emty list
alist = []

#make database_table
db = client.product.serial_key
keyrecord_record = {}

#find table existing entry that code
f_cursor = db.find({"b_p_code": x1})

for document in f_cursor:
    alist.append(document['key'])
    #print(document['key']) //print expected result



if(x1 == ""  or y1==""):
    print("please enter valid no")
else:
    x = algo(x1,y1,alist)

    keys =x.id_generator()
    keys.sort(reverse=True)
    print('\n')
    i=0;
    for x in keys:
        i +=1;
        print('key %d  = ' %i ,  keys[i-1])

        # place values in dictionary
        keyrecord_record = {'key':keys[i-1],'b_p_code':x1}


        #not recived expected result. if key in database again print key
        if(db.serial_key.find({'key':{ '$ne':str(keys[i-1])}})):
            db.insert(keyrecord_record)
        else:
            print('Record in DB')


    print("\n")
    print("Batch No: come from db ")
    print('Generate Key beetween  %d00000 - %d00000'  % (x1 ,(x1+1)) )
    print("Startin Serial : " , keys[0])
    print("Ending  Serial : " , keys[len(keys)-1])



print('\n      Database Details   \n')
#print details
cursor = db.find()

for document in cursor:
    print(document['key'])
    #print(document)

显示控制台输出的图像。

Answer 1

来自mongodb docs：

$ne运算符选择字段值不相等（即！=）的文档到指定值。这包括不包含该字段的文档。

db.serial_key.find({'key':{ '$ne':str(keys[i-1])}})将返回一个mongo游标。因此，无论是否存在相同的值，您的if条件将始终为真，从而导致文档添加。

如果要验证密钥是否已存在，可以查询该值并检查mongo游标数。

以下代码可以解决问题。

for x in keys:
     i +=1;
     print('key %d  = ' %i ,  keys[i-1])  #out put: key 1  =  3ZOHSH

     # place values in dictionary
     keyrecord_record = {'key':keys[i-1],'b_p_code':x1}

     #check if already exists
     if(db.find({'key':str(keys[i-1])}).limit(1).count() == 0):
         db.insert(keyrecord_record)
     else:
         print('Record in DB')

Python db不相等Mongo Code不工作？

1 个答案: