Template rendering (Django): [duplicate] - django

Question

mydict = {"key1":"value1", "key2":"value2"}
The regular way to lookup a dictionary value in a Django template is {{ mydict.key1 }}, {{ mydict.key2 }}. What if the key is a loop variable? ie:
{% for item in list %} # where item has an attribute NAME
{{ mydict.item.NAME }} # I want to look up mydict[item.NAME]
{% endfor %}
mydict.item.NAME fails. How to fix this?

Answer 1

Write a custom template filter:
from django.template.defaulttags import register
...
#register.filter
def get_item(dictionary, key):
return dictionary.get(key)
(I use .get so that if the key is absent, it returns none. If you do dictionary[key] it will raise a KeyError then.)
usage:
{{ mydict|get_item:item.NAME }}

Answer 2

Fetch both the key and the value from the dictionary in the loop:
{% for key, value in mydict.items %}
{{ value }}
{% endfor %}
I find this easier to read and it avoids the need for special coding. I usually need the key and the value inside the loop anyway.

Answer 3

You can't by default. The dot is the separator / trigger for attribute lookup / key lookup / slice.
Dots have a special meaning in template rendering. A dot in a variable
name signifies a lookup. Specifically, when the template system
encounters a dot in a variable name, it tries the following lookups,
in this order:
Dictionary lookup. Example: foo["bar"]
Attribute lookup. Example: foo.bar
List-index lookup. Example: foo[bar]
But you can make a filter which lets you pass in an argument:
https://docs.djangoproject.com/en/dev/howto/custom-template-tags/#writing-custom-template-filters
#register.filter(name='lookup')
def lookup(value, arg):
return value[arg]
{{ mydict|lookup:item.name }}

Answer 4

For me creating a python file named template_filters.py in my App with below content did the job
# coding=utf-8
from django.template.base import Library
register = Library()
#register.filter
def get_item(dictionary, key):
return dictionary.get(key)
usage is like what culebrón said :
{{ mydict|get_item:item.NAME }}

Answer 5

I had a similar situation. However I used a different solution.
In my model I create a property that does the dictionary lookup. In the template I then use the property.
In my model: -
#property
def state_(self):
""" Return the text of the state rather than an integer """
return self.STATE[self.state]
In my template: -
The state is: {{ item.state_ }}

Answer 6

Environment: Django 2.2
Example code:
from django.template.defaulttags import register
#register.filter(name='lookup')
def lookup(value, arg):
return value.get(arg)
I put this code in a file named template_filters.py in my project folder named portfoliomgr
No matter where you put your filter code, make sure you have __init__.py in that folder
Add that file to libraries section in templates section in your projectfolder/settings.py file. For me, it is portfoliomgr/settings.py
TEMPLATES = [
{
'BACKEND': 'django.template.backends.django.DjangoTemplates',
'DIRS': [os.path.join(BASE_DIR, 'templates')],
'APP_DIRS': True,
'OPTIONS': {
'context_processors': [
'django.template.context_processors.debug',
'django.template.context_processors.request',
'django.contrib.auth.context_processors.auth',
'django.contrib.messages.context_processors.messages',
],
'libraries':{
'template_filters': 'portfoliomgr.template_filters',
}
},
},
]
In your html code load the library
{% load template_filters %}

Answer 7

Since I can't comment, let me do this in the form of an answer:
to build on culebrón's answer or Yuji 'Tomita' Tomita's answer, the dictionary passed into the function is in the form of a string, so perhaps use ast.literal_eval to convert the string to a dictionary first, like in this example.
With this edit, the code should look like this:
# code for custom template tag
#register.filter(name='lookup')
def lookup(value, arg):
value_dict = ast.literal_eval(value)
return value_dict.get(arg)
<!--template tag (in the template)-->
{{ mydict|lookup:item.name }}

Answer 8

env: django 2.1.7
view:
dict_objs[query_obj.id] = {'obj': query_obj, 'tag': str_tag}
return render(request, 'obj.html', {'dict_objs': dict_objs})
template:
{% for obj_id,dict_obj in dict_objs.items %}
<td>{{ dict_obj.obj.obj_name }}</td>
<td style="display:none">{{ obj_id }}</td>
<td>{{ forloop.counter }}</td>
<td>{{ dict_obj.obj.update_timestamp|date:"Y-m-d H:i:s"}}</td>