How do I know which groups each product is in?

Question

class Product(models.Model):
    name = models.CharField(max_length=256)

class Group(models.Model):
    name = models.CharField(max_length=32, unique=False)   
    products = models.ManyToManyField(Product, blank=True)

Products in group.pk == 1:

products = Group.objects.get(pk=1).products.all().values('name')

Result:

<QuerySet [
    {"name": "product1"},
    {"name": "product2"},
    {"name": "product3"},
]

How do I know which groups each product is in? Like this:

<QuerySet [
    {"name": "product1", "groups": [{"pk": 1, "name": "group1"}]},
    {"name": "product2", "groups": []"},
    {"name": "product3", "groups": [{"pk": 1, "name": "group1"}, {"pk": 2, "name": "group2"}},
]

Thanks!

UPD1.

If we have data:

group1 | product 1
group1 | product 2
group2 | product 2
group2 | product 3

The idea of creating a table (html) is as follows:

/group/1:

product 1 | dropdown (group1)
product 2 | dropdown (group1, group2)

/group/2:

product 2 | dropdown (group1, group2)
product 3 | dropdown (group2)

Group.objects.get(pk=1).products.all().values() what does this return can you post it? — Exprator, Jun 05 '17 at 11:28
so you are getting group inside the orm, just put group in values and you will get it — Exprator, Jun 05 '17 at 12:00
you can try `map(lambda x: {'name': x.name, 'groups': x.group_set.values('pk', 'name')}, Product.objects.all())` but this will return you as list not as queryset — Ranjith Singhu Ganapathy, Jun 05 '17 at 13:43

score 0 · Answer 1 · answered Jun 05 '17 at 11:30

0

As my understanding, you want to have reverse lookup from your manytomany field to the Model.

You can get the Product groups like this:

Here product is a Product object, and you want to list all the groups associated with that product.

product.group_set.all()

answered Jun 05 '17 at 11:30

Sijan Bhandari

2,941
3
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36

I want to see not only the goods to the group, but also to find out in what other groups this product. group1 (product1, product2), group2(product2, proudct3) => for group1(product1[0], product2[1]), and for group2 (product1 [0], product2 [1]) – ns5d Jun 05 '17 at 12:03
group2 (product2 [1], product3 [0]) * – ns5d Jun 05 '17 at 12:12

Raja Simon · Answer 2 · 2017-06-05T11:37:14.110

0

values takes another argument called 'group' use that to get the related group. Is not giving the expect result you want. But gives idea.

>>> Product.objects.all().values('name', 'group')
<QuerySet [
    {'group': 1, 'name': u'Product 3'}, 
    {'group': 2, 'name': u'Product 3'}, 
    {'group': 1, 'name': u'Product 2'}, 
    {'group': 2, 'name': u'Product 1'}]>

edited Jun 05 '17 at 11:37

answered Jun 05 '17 at 11:30

Raja Simon

10,126
5
43
74

score 0 · Answer 3 · answered Jun 06 '17 at 06:59

Once you have a Product instance:

product = Product.objects.get(pk=1)

it knows which Group instances refer to it. Use the group_set field:

groups = product.group_set.all()

By declaring a related object (using ForeignKey or ManyToManyField), the “other end” of the relationship gets an implied field to access the instances referring to this one.

In this case, the field is named group_set and it is a model manager for Group instances that refer to this Product instance.

score 0 · Accepted Answer · answered Jun 06 '17 at 07:32

0

model.py:

context['products'] = Group.objects.get(pk=1).products.all()
return render(request, 'template.html', context)

template.html:

{% for product in products %}
    {{ product.name }}

    COUNT: {{ product.group_set.count }}
    <ul>
        {% for group in product.group_set.all %}
            <li>{{ group.name }}</li>
        {% endfor %}
    </ul>
{% endfor %}

The solution was not difficult, it got confused because of:

{% for group in slave_product.group_set.all() %} # ()

Thanks to all!

answered Jun 06 '17 at 07:32

ns5d

39
1
7

You never mentioned `template` in your question. – Raja Simon Jun 09 '17 at 12:52
Yes, I was looking for a solution where the answer would be in the query, but it turned out that this could be done using a template – ns5d Jun 29 '17 at 10:41

How do I know which groups each product is in?

4 Answers4