Is it possible with django template tags to skip the first element in a list when doing the for loop? For example I want to begin from element 1 instead from 0.
builtin slice filter
{{ qs|slice:"1:" }}
You can e.g. do:
{% if not forloop.first %}
...
{% endif %}
Related
The model has a field named "is_highlighted", i want to put all items on top if is_highlighted == True when iterate thru the object list.
You can give 2 for loops to do this. In first for loop check the condition true.
{% for x in list %}
{% if x.is_highlighted == True %}
....
..
{% endif %}
{% endfor %}
display others in second for loop
{% for x in list %}
{% if x.is_highlighted != True %}
...
...
You can also pass 2 query sets through context. I don't know if it's best or any other way. simply this will work.
I have some loop on the page and need list item depending from loop number.
When I call:
{{ mylist.1 }}
{{ mylist.2 }}
{{ mylist.3 }}
all works fine but what I really need is something like:
{% for x in somenumber|MyCustomRangeTag %}
{{ mylist.x }}
{% endfor %}
MyCustomRangeTag gives me Python range() it works and I already have x as number. So x is 1, 2, 3 etc. depending from loop number.
Is this possible and how?
This is not possible directly because Django thinks that "x" is the key to lookup in mylist - instead of the value of x. So, when x = 5, Django tries to look up mylist["x"] instead of mylist[5].
Use the following filter as workaround:
#register.filter
def lookup(d, key):
return d[key]
and use it like
{{ mylist|lookup:x }}
The slice tag in Django templates may use python's slicing code, but the syntax is unmistakably different. For instance, if you wanted to get an element of a sequence with a variable, in python you'd write something similar to the following:
>>>mylist = ["0th Element", "1th Element"]
>>>zero, one = 0, 1
>>>mylist[zero]
"0th Element"
>>>mylist[one]
"1th Element"
Using this syntax with the Django slice template tag will return a sliced list in every case, of dubious utility for getting an item of known index:
{% with "0" as zero %}
{% with "1" as one %}
{% with "2" as two %}
{{mylist|slice:zero}} {{mylist|slice:one}} {{mylist|slice:two}}
{% endwith %}
{% endwith %}
{% endwith %}
Renders to the html:
[] ["0th Element"] ["0th Element", "1th Element"]
Note the differences: you are getting the result of mylist[:x] instead of mylist[x].
Django provides enough tools to work around this. The first trick is to use explicit slices like 0:1 for your indices, and then |join:"" the resultant list into a single element. Like so:
{% with "0:1" as zero %}
{{mylist|slice:zero|join:""}}
{% endwith %}
Yields:
0th Element
This comes in particularly handy if you need to access a parent loop's index when dealing with an iterable inside a child loop:
{% for parent in parent_loop %}
{% cycle "0:1" "1:2" "2:3" as parent_loop_index silent %}
{% for child in child_loop %}
{{child|slice:parent_loop_index|join:""}}
{% endfor %}
{% endfor %}
Completed with nothing but stock parts, although I don't think Django has implemented achievements yet.
I notice that #e-satis mentioned it, but I think the built-in slice template tag deserves some love.
{{ item | slice:"2" }} #gets the third element of the list
Are you sure you can't just do:
{% for item in mylist %}
{{ item }}
{% endfor %}
With the slice filter, you can even do some customisation.
Following worked for me
{% for 1,2,3 in mylist %}
# do stuff
Just don't use brackets around 1,2,3
I have the following list:
{% for artist_form in artist_formset %}
...
{% endfor %}
How can I display just the last result in the list?
Thanks
From the docs: https://docs.djangoproject.com/en/1.6/ref/templates/builtins/#last
Use 'last' tag to get the last item of a list.
In views.py:
last_artist = artist_formset[-1]
In your-template.html:
{{ last_artist }}
I am refering to this slice filter: https://docs.djangoproject.com/en/dev/ref/templates/builtins/#slice
if I have this list a=[1, 2, 3, 4, 5], is there any way to take the first half of this list?
Something like {{ a|slice:":3" }}.
But instead of 3 I want the size of list a. And a can have even or odd number of elements. And I don't want to pass the list length as a variable in the context from the view
later EDIT
I was wondering if there is another solution, other than a custom filter
If used in a for-loop, you can do this:
{% for item in a %}
{% if forloop.counter < forloop.revcounter %}
{# first half of list #}
{% else %}
{# second half of list #}
{% endif %}
{% endfor %}
You can do custom filter for this purpose:
#register.filter("half_slice")
def half_slice_filter(value):
return value[:len(value)/2]
I have some loop on the page and need list item depending from loop number.
When I call:
{{ mylist.1 }}
{{ mylist.2 }}
{{ mylist.3 }}
all works fine but what I really need is something like:
{% for x in somenumber|MyCustomRangeTag %}
{{ mylist.x }}
{% endfor %}
MyCustomRangeTag gives me Python range() it works and I already have x as number. So x is 1, 2, 3 etc. depending from loop number.
Is this possible and how?
This is not possible directly because Django thinks that "x" is the key to lookup in mylist - instead of the value of x. So, when x = 5, Django tries to look up mylist["x"] instead of mylist[5].
Use the following filter as workaround:
#register.filter
def lookup(d, key):
return d[key]
and use it like
{{ mylist|lookup:x }}
The slice tag in Django templates may use python's slicing code, but the syntax is unmistakably different. For instance, if you wanted to get an element of a sequence with a variable, in python you'd write something similar to the following:
>>>mylist = ["0th Element", "1th Element"]
>>>zero, one = 0, 1
>>>mylist[zero]
"0th Element"
>>>mylist[one]
"1th Element"
Using this syntax with the Django slice template tag will return a sliced list in every case, of dubious utility for getting an item of known index:
{% with "0" as zero %}
{% with "1" as one %}
{% with "2" as two %}
{{mylist|slice:zero}} {{mylist|slice:one}} {{mylist|slice:two}}
{% endwith %}
{% endwith %}
{% endwith %}
Renders to the html:
[] ["0th Element"] ["0th Element", "1th Element"]
Note the differences: you are getting the result of mylist[:x] instead of mylist[x].
Django provides enough tools to work around this. The first trick is to use explicit slices like 0:1 for your indices, and then |join:"" the resultant list into a single element. Like so:
{% with "0:1" as zero %}
{{mylist|slice:zero|join:""}}
{% endwith %}
Yields:
0th Element
This comes in particularly handy if you need to access a parent loop's index when dealing with an iterable inside a child loop:
{% for parent in parent_loop %}
{% cycle "0:1" "1:2" "2:3" as parent_loop_index silent %}
{% for child in child_loop %}
{{child|slice:parent_loop_index|join:""}}
{% endfor %}
{% endfor %}
Completed with nothing but stock parts, although I don't think Django has implemented achievements yet.
I notice that #e-satis mentioned it, but I think the built-in slice template tag deserves some love.
{{ item | slice:"2" }} #gets the third element of the list
Are you sure you can't just do:
{% for item in mylist %}
{{ item }}
{% endfor %}
With the slice filter, you can even do some customisation.
Following worked for me
{% for 1,2,3 in mylist %}
# do stuff
Just don't use brackets around 1,2,3