this is my views.py :
a=['aaa','bbb','oooo','qqqq','gggg']
def main(request, template_name='index.html'):
context ={
'n':range(len(a)),
'a':a,
}
return render_to_response(template_name, context)
this is my html :
{% for i in n %}
{{a.i}} ww {{a.i+1}}
{% endfor %}
it show ww ww ww ww ww ,
but i want to show 'aaawwbbb bbbwwoooo oooowwqqqq qqqqwwgggg ggggww'
so what can i do ,
thanks
>>> c=Context({'a':['aaa', 'bbb', 'oooo', 'qqqq', 'gggg']})
>>> Template("{% for x in a %}{% if not forloop.first %}{{ x }} {% endif %}{{ x }}ww{% endfor %}").render(c)
u'aaawwbbb bbbwwoooo oooowwqqqq qqqqwwgggg ggggww'
You could create a custom filter, http://docs.djangoproject.com/en/1.2/howto/custom-template-tags/ and have something like this:
# myfilters.py
def return_element(list, index):
return list[index+1]
And then you can use it from the template,
{% include myfilters %}
...
{% for i in a %}
{{ i }}ww{{ a|return_element:forloop.counter0 }}
{% endfor %}
The forloop template variable is automatically set within a for tag.. forloop.counter0 returns the number of times loop is entered, and uses zero-indexing.
Don't do that. Iterate on list directly.
context = {
'a': a
}
return render_to_response(template_name, context)
And in template:
{% for x in a %}
{{ x }}
{% endfor %}
Related
{% for each_item in item.artifacts %}
{% if each_item.scanner_count > 0 and each_item.scanner_match > 0 %}
{% if forloop.counter <= 5 %}
<tr>
<td>{{each_item.threat_name}}</td>
</tr>
{% else %}
{% if forloop.last %}
<p><b><i> {{ forloop.counter|add:"-5" }} rows were truncated. See full report for more details. </i></b></p>
{% endif %}
{% endif %}
{% else forloop.counter -=1 %}
{% endif %}
{% endfor %}
ERROR:Malformed template tag at line 171: "else forloop.counter -=1"
I want to increment the counter only when if condition is successful. Dont know how to do it with forloop.counter. Goal is to print 5 rows of valid output(scanner count >0 and Scanner match >0)
You can use combination of add and forloop counter to achieve what you want to achieve. But remember you need to pass some variable (I've used rank here for kinda storing the increment variable in template.
views.py
rank = 0
return render(request, "base.html", {"items": items, "rank": rank})
html
{% for each_item in items %}
{% if each_item.scanner_count > 0 and each_item.scanner_match > 0 %}
{% if forloop.counter|add:rank <= 5 %}
<tr><td>{{each_item.threat_name}}</td></tr>
<br>
{% else %}
{% if forloop.last %}
<p><b><i> {{ forloop.counter|add:"-5" }} rows were truncated. See full report for more details. </i></b></p>
{% endif %}
{% endif %}
{% endif %}
{% endfor %}
As other commenters have noted, you cannot make an assignment of the forloop.counter in the template, as that would be considered logic that should be in the view (controller). Remove the {% else forloop.counter -= 1 %} from your code and it should work as I think you intended. If not, either add logic in the object (context) being passed to the template or user other forloop attributes/variables as found in the Django documentation here: https://docs.djangoproject.com/en/3.0/ref/templates/builtins/#for
I want to declare a flag variable in django template and the change it if some thing happened.
But when I change value of variable by custom tag it is declared a new variable and doesn't change.
for example my template tag and django template is:
template tag:
#register.simple_tag
def update_variable(value):
return value
html:
{% with True as flag %}
<h1>1: {{ flag }}</h1>
{% for e in events %}
{% if e.title == '***' %}
{% update_variable False as flag %}
<h1>2: {{ flag }}</h1>
{% endif %}
{% endfor %}
<h1>3: {{ flag }}</h1>
{% endwith %}
and result is:
1: True
2: False
3: True
But the end result should be False! How to do this?
I find a solution for it. for check all element of list we can use custom filter an do some thing there:
html:
//load custom filter
{% load my_filters %}
{% if "anything we want"|is_in:events.all %}
//do some thing...
{% else %}
//do some thing...
{% end if%}
custom filter in my_filter file:
register = template.Library()
def is_in(case, list):
for element in list:
if element.time_span == case:
return True
return False
register.filter(is_in)
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 %}
I want to reduce the number of template filter calls in my_filter_function(). Because It's used inside two for-loops inside a template. Please see below for my code setup.
class ModelA(models.model):
models.ForeignKey(OtherModel1)
class ModelB(models.model):
models.ForeignKey(OtherModel2)
class ModelC(models.Model):
a = models.ForeignKey(ModelA)
b = models.ForeignKey(ModelB)
def my_views(request):
return render(request, 'my_template.html', {
'a_list': ModelA.objects.all(),
'b_list': ModelB.objects.all(),
})
and in my template, I have
{% for a in a_list %}
{% for b in b_list %}
{% with b|my_filter_function:a as my_val %}
Val: {{my_val}}
{% endwith %}
{% endfor %}
{% endfor %}
the above template will will call the my_filter_function filter function, I need to find another way to reduce the number of my_filter_function function calls, because the filter function is accessing the DBs several thousand times per template now.
#register.filter
def my_filter_function:(b, a):
z = ModelC.objects.filter(a=a, b=b)
if z.count() > 0:
return "OK"
else:
return "Not OK"
Here's a faster alternative.
Fetch all the ids of A and B in C at once:
z = ModelC.objects.values_list('a_id', 'b_id')
a_related, b_related = zip(*z) # split into a and b ids
Pass these to your context:
def my_views(request):
return render(request, 'my_template.html', {
'a_list': ModelA.objects.all(),
'b_list': ModelB.objects.all(),
'a_related': a_related,
'b_related': b_related,
})
And then use if...in in your template. The custom template filter can now be discarded:
{% for a in a_list %}
{% for b in b_list %}
{% if a.id in a_related and b.id in b_related %}
"OK"
{% else %}
"Not ok"
{% endif %}
{% endfor %}
{% endfor %}
That replaces all the multiple queries in your filter with just one.
I want to change the value of the variable declared outside the loop within a loop. But always changing, it keeps the initial value outside the loop.
{% set foo = False %}
{% for item in items %}
{% set foo = True %}
{% if foo %} Ok(1)! {% endif %}
{% endfor %}
{% if foo %} Ok(2)! {% endif %}
This renders:
Ok(1)!
So the only (bad) solution have found so far was this:
{% set foo = [] %}
{% for item in items %}
{% if foo.append(True) %} {% endif %}
{% if foo %} Ok(1)! {% endif %}
{% endfor %}
{% if foo %} Ok(2)! {% endif %}
This renders:
Ok(1)!
Ok(2)!
But, its is very ugly! Is there another more elegant solution?
Try also dictionary-based approach. It seems to be less ugly.
{% set vars = {'foo': False} %}
{% for item in items %}
{% if vars.update({'foo': True}) %} {% endif %}
{% if vars.foo %} Ok(1)! {% endif %}
{% endfor %}
{% if vars.foo %} Ok(2)! {% endif %}
This also renders:
Ok(1)!
Ok(2)!
as mentioned in the documentation:
Please note that assignments in loops will be cleared at the end of
the iteration and cannot outlive the loop scope.
but as of version 2.10 you can use namespaces:
{% set ns = namespace(foo=false) %}
{% for item in items %}
{% set ns.foo = True %}
{% if ns.foo %} Ok(1)! {% endif %}
{% endfor %}
{% if ns.foo %} Ok(2)! {% endif %}
You could do this to clean up the template code
{% for item in items %}
{{ set_foo_is_true(local_vars) }}
{% if local_vars.foo %} Ok(1)! {% endif %}
{% endfor %}
{% if local_vars.foo %} Ok(2)! {% endif %}
And in the server code use
items = ['item1', 'item2', 'item3']
#---------------------------------------------
local_vars = { 'foo': False }
def set_foo_is_true(local_vars):
local_vars['foo'] = True
return ''
env.globals['set_foo_is_true'] = set_foo_is_true
#---------------------------------------------
return env.get_template('template.html').render(items=items, local_vars=local_vars)
This could be generalized to the following
{{ set_local_var(local_vars, "foo", False) }}
{% for item in items %}
{{ set_local_var(local_vars, "foo", True) }}
{% if local_vars.foo %} Ok(1)! {% endif %}
{% endfor %}
{% if local_vars.foo %} Ok(2)! {% endif %}
And in the server code use
items = ['item1', 'item2', 'item3']
#---------------------------------------------
local_vars = { 'foo': False }
def set_local_var(local_vars, name, value):
local_vars[name] = value
return ''
env.globals['set_local_var'] = set_local_var
#---------------------------------------------
return env.get_template('template.html').render(items=items, local_vars=local_vars)