Python – Passing variables to custom Django template tags

djangodjango-templatespython

I'm adding an autocomplete feature to my django application.

HTML

<script type="text/javascript"> 
            var a = {% get_fields_task_name %}
            $( "#auto_task_name" ).autocomplete({
              source: a           
            });

view

def get_fields_task_name():    
    task = Task.objects.all()    
    output = []

    for e in task:
        output.append(e.name)

    x = json.dumps(output)
    return x
get_fields_task_name = register.simple_tag(get_fields_task_name)

I need to pass parameters to get_fields_task_name, how can I do this in the template instead of {% get_fields_task_name %}?

Best Answer

This depends on exactly what the parameters are, but if it's something you can get in a single variable at template rendering time, just add it as a parameter to the function (see the docs for simple_tag).

For example:

@register.simple_tag
def get_fields_task_name(kind):
    tasks = Task.objects.filter(kind=kind)
    return json.dumps([e.name for e in tasks])

(using a list comprehension to make the function body shorter and cleaner, and also using the nicer decorator syntax).

Then you can just change the relevant line in the template to

var a = {% get_fields_task_name some_variable.kind %};

Related Solutions

Python – Are static class variables possible in Python

Variables declared inside the class definition, but not inside a method are class or static variables:

>>> class MyClass:
...     i = 3
...
>>> MyClass.i
3

As @millerdev points out, this creates a class-level i variable, but this is distinct from any instance-level i variable, so you could have

>>> m = MyClass()
>>> m.i = 4
>>> MyClass.i, m.i
>>> (3, 4)

This is different from C++ and Java, but not so different from C#, where a static member can't be accessed using a reference to an instance.

See what the Python tutorial has to say on the subject of classes and class objects.

@Steve Johnson has already answered regarding static methods, also documented under "Built-in Functions" in the Python Library Reference.

class C:
    @staticmethod
    def f(arg1, arg2, ...): ...

@beidy recommends classmethods over staticmethod, as the method then receives the class type as the first argument, but I'm still a little fuzzy on the advantages of this approach over staticmethod. If you are too, then it probably doesn't matter.

Javascript – Django Template Variables and Javascript

The {{variable}} is substituted directly into the HTML. Do a view source; it isn't a "variable" or anything like it. It's just rendered text.

Having said that, you can put this kind of substitution into your JavaScript.

<script type="text/javascript"> 
   var a = "{{someDjangoVariable}}";
</script>

This gives you "dynamic" javascript.

Best Answer

Related Solutions

Python – Are static class variables possible in Python

Javascript – Django Template Variables and Javascript

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