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How to iterate through multidimensional list/dict in a template

I try to rebuild this example:
https://blog.roseman.org.uk/2010/01/11/django-patterns-part-2-efficient-reverse-lookups/
I have a model "Product" and a model "Order". Order has a foreignkey to "product". So for 1 Product I have N Orders
In my template I have to display a lot of information so I would like to avoid to do "for order in Product.order_set.all()" in my template
In my template, if I write :
{{ object_list.1.related_items }}
everything is fine and I get what I want
but if I write:
{% for i in object_list %}
{{ object_list.i.related_items }}
{% endfor %}
I don't get a result.
Can somebody tell me how I solve this problem?
My object_list is nearly the same as in the above example:
products = Product.objects.all()
i = 0
qs = Product.objects.all()
obj_dict = dict([(obj.id, obj) for obj in qs])
objects = Order.objects.filter(producttyp__in=qs)
relation_dict = {}
for obj in objects:
relation_dict.setdefault(obj.producttyp_id, []).append(obj)
for id, related_items in relation_dict.items():
obj_dict[id].related_items = related_items
def get(self,request,*args,**kwargs):
context = {'object_list':self.obj_dict}
return render(request,self.template_name,context)
the only change i did is from
obj_dict[id]._related_items to obj_dict[id].related_items because of the not allowed underscore?!
How do I print the list in my template like:
- Product A
- Order 1
- Order 2
- Order 5
- Product B
- Order 3
- Order 6
best regards

That is logical, since here Django interprets i not as the variable, but as the an identifier, so it aims to access object_list.i, or object_list['i'], not object_list.1 for example.
You however do not need i here, you can just access the related_items of the object, like:
{% for object in object_list %}
{{ object.related_items }}
{% endfor %}
If related_items is, as the name suggests, a collection as well, we can iterate over these items as well:
{% for object in object_list %}
{% for subitem in object.related_items %}
{{ subitem }}
{% endfor %}
{% endfor %}
for a dictionary, we can access the .values, like:
{% for object in object_dict.values %}
{{ object.related_items }}
{% endfor %}
EDIT: as for the specific case of the listview. You can use .prefetch_related to fetch all the relations with one extra query:
class MyListView(ListView):
queryset = Product.objects.prefetch_related('order_set')
template = 'my_template.html'
In the template you can then render this like:
<ul>
{% for product in object_list %}
<li>{{ product }}</li>
<ul>
{% for order in product.order_set %}
<li>{{ order }}</li>
{% endfor %}
</ul>
{% endfor %}
</ul>

How can i access a jinja2 variable outside the for loop?

im trying to use a for loop to add up some numbers for each day
and i would like to access the variable outside the for loop im not sure how to go about this I am using the flask framework with python and just come from weppy where this was not a problem is there a way to make it work the same way in flask?
here is some simple code
{% set newtotal = 0 %}
{% for item in daily: %}
{% set newtotal = newtotal + item[10]|float %}
{% endfor %}
<div class="bottom">
<span>Total: {{ newtotal }}</span>
</div>
the numbers collected by item[10] are dollar values
if i place the {{ newtotal }} before the endfor it shows every value as its being added up this is not what I want
EDIT:
if it helps daily is a list of 8 tuples

Please keep in mind that it is not possible to set variables inside a block or loop and have them show up outside of it.
As of version 2.10 this can be handled using namespace objects which allow propagating of changes across scopes.
Here is your code using namespace:
{% set ns = namespace (newtotal = 0) %}
{% for item in daily: %}
{% set ns.newtotal = ns.newtotal + item[10]|float %}
{% endfor %}
<div class="bottom">
<span>Total: {{ ns.newtotal }}</span>
</div>

One solution (probably the "simplest") would be to change your Python script to pass in a variable named newtotal that would simply be the length of the daily list!
Alternatively, you could use the length filter:
{{things|length}}
In which case your code could look something like this:
{% set newtotal = 0 %}
{% for item in daily: %}
{% set newtotal = newtotal + item[10]|float %}
{% endfor %}
<div class="bottom">
<span>Total: {{daily|length}}</span>
</div>
Hope it helps!
Additional Sources:
jinja2: get lengths of list
How do I access Jinja2 for loop variables outside the loop?
EDIT
Sorry, I misread the question!
You can use the sum filter instead ({{ list | sum() }}).
So your code could look like:
{% set newtotal = 0 %}
{% for item in daily: %}
{% set newtotal = newtotal + item[10]|float %}
{% endfor %}
<div class="bottom">
<span>Total: {{ daily | sum() }}</span>
</div>
New sources:
Documentation
Sum elements of the list in Jinja 2

Use the namespace object.
https://jinja.palletsprojects.com/en/master/templates/#assignments
Here’s a working example from my config.
{% set i= namespace(fxp0_ip=0) %}
{% set i= namespace(mgmt_ip = 0) %}
{% set i= namespace(loopback_ip = 0) %}
{% set i= namespace(lan_ip = 0) %}
{% set i= namespace(wan_ip = 0) %}
{% for interface in device_vars.interfaces %}
{% elif interface.name == "ge-0/0/0" %}
{% set i.mgmt_ip = interface.ip_addr %}
{% elif interface.name == "lo0" %}
{% set i.loopback_ip = interface.ip_addr %}
{% elif interface.name == "ge-0/0/2" %}
{% set i.lan_ip = interface.ip_addr %}
{% elif interface.name == "ge-0/0/1" %}
{% set i.wan_ip = interface.ip_addr %}
{% endif %}
{% endfor %}
{{i.mgmt_ip}}
{{i.wan_ip}}

Jinja2/Python - Strings to Integers for comparison

I have strings like the following:
Team Li vs. Team Aguilar || SCORE (W-L-T): 5-4-0
Favors Flavors vs. Cupcakes For Breakfast || SCORE (W-L-T): 11-2-1
I would like the text to be green if the "W" value is greater than the "L" value, and red if the "L" value is greater than the "W" value. I have the following code in Jinja2 that works for the first case, but does not work for the second case. It incorrectly displays the string as red, even though the "W" column is greater than the L column.
{% for item in matchups %}
{% if (item[-5]|int) > (item[-3]|int) %}
<font color='green'>{{ item }}</font>
{% elif (item[-5]|int) == (item[-3]|int) %}
{{ item }}
{% else %}
<font color='red'>{{ item }}</font>
{% endif %}
<br>
{% endfor %}
I understand that my code fails because the second string has 2 digits. Is there a good way to fix this issue?
This is a Jinja2 problem, so answers in Jinja2 would be great. However, a Python solution might also work too.

You can extract the elements with two splits (using variables for clarity):
first to get the last column (split by whitespace) element:
{% set results = item.split()[-1] %}
then to get the first and second of the results (split by the dash):
{% set w = results.split('-')[0]|int %}
{% set l = results.split('-')[1]|int %}
The full code (also with a condition to process only lines containing SCORE to handle the one from your now-edited-out example with *************):
{% for item in matchups %}
{% if 'SCORE' in item %}
{% set results = item.split()[-1] %}
{% set w = results.split('-')[0]|int %}
{% set l = results.split('-')[1]|int %}
{% if w > l %}
<font color='green'>{{ item }}</font>
{% elif w == l %}
{{ item }}
{% else %}
<font color='red'>{{ item }}</font>
{% endif %}
<br>
{% endif %}
{% endfor %}

How to tell list from non-list in Django template?

I've got a Django template I'd sometimes like to pass a list and sometimes like to pass a single value. How can the template tell which it was given?
I'm thinking the value would be set like one of these:
context = {
'foo' : 'bar
}
or:
context = {
'foo' : ['bar', 'bat', 'baz']
}
Then, the template would have code that looks something like this:
{% if foo isa list %}
{% for item in foo %}
{{ item }}<br>
{% endfor %}
{% else %}
{{ item}}<br>
{% endif %}
I can set it up to have foo or foolist, for example, and check for one or the other. However, it'd be a bit nicer (imo) to just have foo that was either a list or not.

If you intend to do it this way then just add a check that it doesn't have format(in case of string) method and has 0 index, if so then its a list else considered single value
{% if foo.0 and not foo.format %}
{% for item in foo %}
{{ item }}<br>
{% endfor %}
{% else %}
{{ item}}<br>
{% endif %}

I think your approach is needlessly complicated.
I would just go with a list:
views.py
foo_list = ['bar']
context = {
'foo': foo_list,
'foo_len': len(foo_list),
}
template
{% if foo_len == 1 %}
{{ foo.0 }}
{% else %}
{% for item in foo %}
{{ item }}
{% endfor %}
{% endif %}

Django - How to do tuple unpacking in a template 'for' loop

In my views.py, I'm building a list of two-tuples, where the second item in the tuple is another list, like this:
[ Product_Type_1, [ product_1, product_2 ],
Product_Type_2, [ product_3, product_4 ]]
In plain old Python, I could iteration the list like this:
for product_type, products in list:
print product_type
for product in products:
print product
I can't seem to do the same thing in my Django template:
{% for product_type, products in product_list %}
print product_type
{% for product in products %}
print product
{% endfor %}
{% endfor %}
I get this error from Django:
Caught an exception while rendering: zip argument #2 must support iteration
Of course, there is some HTML markup in the template, not print statements. Is tuple unpacking not supported in the Django template language? Or am I going about this the wrong way? All I am trying to do is display a simple hierarchy of objects - there are several product types, each with several products (in models.py, Product has a foreign key to Product_type, a simple one-to-many relationship).
Obviously, I am quite new to Django, so any input would be appreciated.

Another way is as follows.
If one has a list of tuples say:
mylst = [(a, b, c), (x, y, z), (l, m, n)]
then one can unpack this list in the template file in the following manner.
In my case I had a list of tuples which contained the URL, title, and summary of a document.
{% for item in mylst %}
{{ item.0 }} {{ item.1}} {{ item.2 }}
{% endfor %}

it would be best if you construct your data like {note the '(' and ')' can be exchanged for '[' and ']' repectively, one being for tuples, one for lists}
[ (Product_Type_1, ( product_1, product_2 )),
(Product_Type_2, ( product_3, product_4 )) ]
and have the template do this:
{% for product_type, products in product_type_list %}
{{ product_type }}
{% for product in products %}
{{ product }}
{% endfor %}
{% endfor %}
the way tuples/lists are unpacked in for loops is based on the item returned by the list iterator.
each iteration only one item was returned. the first time around the loop, Product_Type_1, the second your list of products...

You must used this way:
{% for product_type, products in product_list.items %}
{{ product_type }}
{% for product in products %}
{{ product }}
{% endfor %}
{% endfor %}
Don't forget the variable items in the dictionary data

If you have a fixed number in your tuples, you could just use indexing. I needed to mix a dictionary and the values were tuples, so I did this:
In the view:
my_dict = {'parrot': ('dead', 'stone'), 'lumberjack': ('sleep_all_night', 'work_all_day')}
In the template:
<select>
{% for key, tuple in my_dict.items %}
<option value="{{ key }}" important-attr="{{ tuple.0 }}">{{ tuple.1 }}</option>
{% endfor %}
</select>

Just send the template a list of product types and do something like:
{% for product_type in product_type_list %}
{{ product_type }}
{% for product in product_type.products.all %}
{{ product }}
{% endfor %}
{% endfor %}
It's been a little while so I can't remember exactly what the syntax is, let me know if that works. Check the documentation.