How to populate a ManyToMany Field in Django using a .csv file?

问题

I have 2 models Influencer and Category. Influencer has a many to many relationship with Category.The models look like this:

class Category(models.Model):
    name = models.CharField(max_length=100)

    def __str__(self):
        return self.name

and

class Influencer(models.Model):
    full_name = models.CharField('Full Name',max_length=100)
    username = models.CharField('Username',max_length=100,unique=True)
    photo = models.ImageField(upload_to = 'photos/%Y/%m/%d/',blank=True)
    location_city = models.CharField('Location City',max_length=100,null=True,blank=True)
        categories = models.ManyToManyField(Category)

I have written a python script that parses a csv file and sends the data to a PostgreSQL database.

In the csv file the column Category is present as an array, like the one given below

['Food', 'Bar', 'Bar', 'Student', 'Student', 'makeup', 'makeup', 'India', 'India']

A screenshot of the csv file

When I print the type of column Category in python it shows it as a string. The function which I wrote to parse and send data to database is as follows.I have excluded the categories option from the function for now.

def write_to_db(file):
    with open(str(file),encoding='utf-8') as csvfile:
            csvreader = csv.reader(csvfile)
            next(csvreader,None)
            for row in csvreader:

                try:
                    if not Influencer.objects.filter(username = row[1]).exists() and check_email(row[2]):
                        _,created = Influencer.objects.get_or_create(
                                full_name = row[0],
                                username = row[1],
                                email_id = clean_email(row[2]),
                                external_url = row[8],


                                )

                except Exception as e:
                    print(e)

How should I write the code so that I can insert the categories in the many to many field with the respective Primary key of influencer.

Are there any other alternatives other than using a ManyToManyField? I have tried django-multiselected field but it doesn't work well.

回答1:

This should do the trick:

import ast

def write_to_db(file):
    with open(str(file),encoding='utf-8') as csvfile:
        csvreader = csv.reader(csvfile)
        next(csvreader,None)
        for row in csvreader:
            try:
                if not check_email(row[2]):
                    continue
                influencer, _ = Influencer.objects.get_or_create(
                    full_name = row[0],
                    username = row[1],
                    email_id = clean_email(row[2]),
                    external_url = row[8],
                )
                categories_str = row[5]
                category_names = ast.literal_eval(categories_str)
                category_names = map(str.lower, category_names) # normalize them, all lowercase
                category_names = list(set(category_names)) # remove duplicates
                for category_name in category_names:
                    category, _ = Category.objects.get_or_create(name=category_name)
                    influencer.categories.add(category)
            except Exception as e:
                print(e)

I'm assuming the format I see there in the categories column is consistent with the snippet you pasted (using single quotes and [] to denote a list). In that case the ast module can be used to parse this column directly into a python literal, a list of strings ;)

来源：https://stackoverflow.com/questions/56768792/how-to-populate-a-manytomany-field-in-django-using-a-csv-file