I am trying to use batch_writer() in DynamoDB (Amazon Web Services). I read the first CSV, store each header in a Dict.

CSV #1 -> I have 3 Dicts (Country Name, Language, ISO3). Country Name is the PRIMARY KEY in my DynamoDb table.

CSV #2 -> I only want to store 1 column from the CSV so I have only 1 Dict (Area).

When I upload the values, it does not loop through every value in Area, like it does for the 3 dicts in CSV 1.

        with open('shortlist_languages.csv', 'r') as file:
            reader = csv.DictReader(file)

            for row in reader:
                country_name = {
                    'Country Name': row['Country Name']
                }

                languages = {
                    'Languages': row['Languages']
                }

                iso3 = {
                    'ISO3': row['ISO3']
                }
                with open('shortlist_area.csv', 'r') as file_area:

                    reader_area = csv.DictReader(file_area)
                    for row in reader_area:
                        area = {
                            'Area': row['Area']
                        }
                        
                        for vals_area in area.values():
                            for value in country_name.values():
                                print(value)
                                for values in languages.values():
                                    for values_iso3 in iso3.values():
                                        with table.batch_writer(overwrite_by_pkeys=['Country Name']) as batch:
                                            batch.put_item(
                                                Item={
                                                    'Country Name': value,
                                                    'Languages': values,
                                                    'ISO3': values_iso3,
                                                    'Area':vals_area
                                                }
                                            )

Screenshot of my DynamoDB table--as you can see Area is not looping properly. The last value of Area in my CSV is repeatedly printing. How can i fix that?

CSV#1 Sample:

ISO3,Country Name,Languages
ALB,Albania,Albanian
DZA,Algeria,Arabic,Tamazight
AND,Andorra,Catalan
AGO,Angola,Portuguese

CSV #2 Sample

ISO3,Country Name,Area
ALB,Albania,28748
DZA,Algeria,2381741
AND,Andorra,468
AGO,Angola,1246700

CodePudding user response：

Your code is nested incorrectly. Here is some example code that first reads the languages file into a dictionary, then loops through the area file:

languages = {}
table = []

# Load languages, catering for multiple languages
with open('shortlist_languages.csv') as languages_file:
    for line in languages_file:
        fields = line.strip().split(',')
        languages[fields[0]] = ','.join(fields[2:])

# Load countries
with open('shortlist_area.csv') as countries_file:
    for line in countries_file:
        fields = line.strip().split(',')
        table.append(
            {
                'Country Name': fields[1],
                'Languages': languages[fields[0]],
                'ISO3': fields[0],
                'Area': fields[2]
 
            }
        )

print(table)

(I was too lazy to use the CSV functions!)

The output is:

[
    {
        "Country Name": "Country Name",
        "Languages": "Languages",
        "ISO3": "ISO3",
        "Area": "Area"
    },
    {
        "Country Name": "Albania",
        "Languages": "Albanian",
        "ISO3": "ALB",
        "Area": "28748"
    },
    {
        "Country Name": "Algeria",
        "Languages": "Arabic,Tamazight",
        "ISO3": "DZA",
        "Area": "2381741"
    },
    {
        "Country Name": "Andorra",
        "Languages": "Catalan",
        "ISO3": "AND",
        "Area": "468"
    },
    {
        "Country Name": "Angola",
        "Languages": "Portuguese",
        "ISO3": "AGO",
        "Area": "1246700"
    }
]

Note that Algeria has multiple languages in its output.