将 Null 项目插入集合 Mongodb (Pymongo)

Question

Disclaimer: I'm a newbie when it comes to mongo..

So i have this data from a text-file that i am processing into "python dictionary" format so that it can be inserted into a collection i created using Pymongo.

raw data changed to text, apologies... can be viewed here on pastebin Link to raw data text

And here is the formatted dictionary in python for insertion

[{'Poll_Name': 'ECU', 'Date': '2020-05-07', 'Sample_Size': '--', 'MoE': '--', 'Biden (D)': '46', 'Trump(R)': '43', 'Spread': 'Trump +3'}, {'Poll_Name': 'WRAL-TV', 'Date': '2020-04-23', 'Sample_Size': '580 LV', 'MoE': '5.5', 'Biden (D)': '45', 'Trump(R)': '50', 'Spread': 'Biden +5'}, {'Poll_Name': 'PPP (D)', 'Date': '2020-04-14', 'Sample_Size': '1318 RV', 'MoE': '2.7', 'Biden (D)': '47', 'Trump(R)': '48', 'Spread': 'Biden +1'}, {'Poll_Name': 'Civitas', 'Date': '2020-04-05', 'Sample_Size': '500 LV', 'MoE': '4.4', 'Biden (D)': '49', 'Trump(R)': '42', 'Spread': 'Trump +7'}]

I have all the dictionary data inserted into an array and the i plan to do an insertmany() with it.

Here is the code i have so far for the exporting of this data in dictionary format

def export_Data(filename):
export_List = [] #list that will contain the dictionary values of the data
key_List = ["Poll_Name", "Date", "Sample_Size", "MoE", "Biden (D)", "Trump(R)", "Spread"] #list of keys for each value
count = 0 
temp_List = []
with(open(filename, "r")) as infile: #opening the file of raw data
    for line in infile:
        count += 1
        temp_List.append(line.strip("\n")) #i add each line of infile to this temporary list 
        if count % len(key_List) == 0: #when 7 items are added
            temp_dict = {} #create a temporary dictionary 
            for key, line in zip(key_List, temp_List): #fill in dictionary key values..
                temp_dict[key] = line
            temp_List = [] # resetting the temporary dictionary
            export_List.append(temp_dict) #appending dictionary to final list
print(export_List)
#export the list later once i get properly formatted..

Now as you can see some of the entries found in both the text file and the dictionary sample are seen as "--", these are suppost to represent empty/null values. I want to insert values like these as null and not "--" into my database so as to avoid having to do a mass update query in mongo, i feel like it might make the data cleaning/export process simpler and faster. Is there any way i can change these values so they can be inserted as null instead of "--" Would appreciate any solutions, I know there is probably a simple answer. but this newbie would appreciate some clarification.

Answer 1

You can explicitly replace "--" with any value of your choice in that loop:

instead of

        temp_List.append(line.strip("\n")) 

        temp_str = line.strip("\n")
        temp_list.append(temp_str if (temp_str != "--") else "")

If you would rather use null or undefined or "Not Provided" or whatever, just replace "" with what you'd like to use.