many-to-many in list display django

You may not be able to do it directly. From the documentation of list_display

ManyToManyField fields aren’t supported, because that would entail executing a separate SQL statement for each row in the table. If you want to do this nonetheless, give your model a custom method, and add that method’s name to list_display. (See below for more on custom methods in list_display.)

You can do something like this:

class PurchaseOrderAdmin(admin.ModelAdmin):    fields = ['product', 'dollar_amount']    list_display = ('get_products', 'vendor')    def get_products(self, obj):        return "\n".join([p.products for p in obj.product.all()])

OR define a model method, and use that

class PurchaseOrder(models.Model):    product = models.ManyToManyField('Product')    vendor = models.ForeignKey('VendorProfile')    dollar_amount = models.FloatField(verbose_name='Price')    def get_products(self):        return "\n".join([p.products for p in self.product.all()])

and in the admin list_display

list_display = ('get_products', 'vendor')

This way you can do it, kindly checkout the following snippet:

class Categories(models.Model):    """ Base category model class """    title       = models.CharField(max_length=100)    description = models.TextField()    parent      = models.ManyToManyField('self', default=None, blank=True)    when        = models.DateTimeField('date created', auto_now_add=True)    def get_parents(self):        return ",".join([str(p) for p in self.parent.all()])    def __unicode__(self):        return "{0}".format(self.title)

And in your admin.py module call method as follows:

class categories(admin.ModelAdmin):    list_display    = ('title', 'get_parents', 'when')

I you want to save extra queries you can add a prefetch_related

class PurchaseOrderAdmin(admin.ModelAdmin):    fields = ['product', 'dollar_amount']    list_display = ('get_products', 'vendor')    def get_queryset(self, request):        qs = super().get_queryset(request)        return qs.prefetch_related('product')    def get_products(self, obj):        return ",".join([p.products for p in obj.product.all()])