TemplateTAGS em Django (e ClassyTags)

Django4FrontEnd

Autor: Carlos Batman

TemplateTAGS in Django

Django4FrontEnd

Author: Carlos Batman

Templatetags em Django - Django4FrontEnd

fonte: Django Project Docs

Expressões que podem ser usadas em templates django para gerar ou adaptar conteúdo.

Ligam funções a templates

• {{variável|filtro}}
• {% tags %} (template próprio? acesso a contexto?)

{% templatetag %}

Ativação de templatetags

Templatetags em Django - Django4FrontEnd

# templatetags/appname_tags.py

from django import template
# ... any other imports you need...

register = template.Library()

@register.inclusion_tag('dumbtemplate.html')
def obter_transformada(*args):
    '''
    ...
    '''
    

fonte: Django Project Docs

1. Criar pasta templatetags em aplicação django
2. Adicionar ficheiro chamado __init__.py
3. criar ficheiro para tags (normalmente appname_tags.py)
4. Adicionar aplicação django ao INSTALLED_APPS  em settings.py
5. adicionar E registar tags
6. carregar as tags no template desejado

{% load appname_tags %}

<!-- template.html -->

{% obter_transformada 'a' 'b' 'c' %}
    

Templates em Django - Django4FrontEnd

the Django template system is not simply Python embedded into HTML.

 

This is by design: the template system is meant to express presentation, not program logic

fonte: https://docs.djangoproject.com/en/1.8/topics/templates/

Templatetags em Django - Django4FrontEnd

{% exemplos %}

@register.filter
def as_comma_separated_string(list_of_stringable_items):
    """
    Returns a string composed of all items on a list, separated by a comma and a space

    .. warning: Each item on the list must be convertible to a string without error

    :param      list_of_stringable_items:  The list of stringable items to be enumerated
    :type       list_of_stringable_items:  list (or something enurable, but list is the expected type)

    :returns:   a string containing all items on the list, separated by commas
    :rtype:     { string }

    :Example:

    ..code-block:: html
    
    <!-- if some list is ['a', 'whatever'] -->
    {{ some_list|as_comma_separated_string }}
    <!-- will return 'a, whatever' -->
    """
    return ', '.join([str(item) for item in list_of_stringable_items])

Exemplo 1 - Filtro

Tipos de Templatetag

Templates em Django - Django4FrontEnd

{{ filtro }}

Templatetags em Django - Django4FrontEnd

@register.filter
def filtro(value, arg=None):
    '''
    Returns a string with ' filtrada' appended to the string representation of 'value'.
    If an additional argument is sent, 
    it also appends ' com ' and the value of 'arg' to the returned value 

    :param: value   The value to be filtered
    :type: value    String, or any other value that can be converted to a string
    :param: arg     An additional argument
    :type: arg      String, or any other value that can be converted to a string   
    :returns:       A string similar to the first parameter's value and some additional content
    :rtype:         String

    .. code-block:: html

    {{ 'text'|filtro:'whatever' }}  
    
    '''
    if not arg:
        return "%s filtrada" % (value)
    else:
        return "%s filtrada com %s" (value, arg)

{% simples %}

Templatetags em Django - Django4FrontEnd

@register.simple_tag
def obter_transformada(*args):
    '''
    Returns a string with 'Transformada fica: ' and the value(s) of all parameters  
    appended to it, separated by spaces.

    :returns:       A string similar to the first parameter's value and some additional content
    :rtype:         String

    .. code-block:: html

    {% obter_transformada 'It is' 'done' 'ok not yet' 'now it is' %}  
    
    '''
    return " ".join([str(arg) for arg in args])

fonte: Django Project Docs

{% de_inclusao %}

Templatetags em Django - Django4FrontEnd

@register.inclusion_tag('dumbtemplate.html')
def obter_transformada(*args):
    '''
    ...
    '''
    return {
        "quote": " ".join([str(arg) for arg in args])
    }

fonte: Django Project Docs

Mesma coisa que 'simples', mas:

• o resultado é exibido num formato definido por template!
• é preciso retornar dicionário que será o contexto desse template

<!-- dumbtemplate.html -->
<p>
  Your answer: {{ quote }}
</p>

{% de_associacao as x %}

Templatetags em Django - Django4FrontEnd

@register.assignment_tag
def obter_transformada(*args):
    '''
    Returns a string with 'Transformada fica: ' and the value(s) of all parameters  
    appended to it, separated by spaces.

    :returns: A string similar to the first parameter's value and some additional content
    :rtype:   String

    .. code-block:: html

    {% obter_transformada 'It is' 'done' as transformada %}
    {{ transformada }}
 
    '''
    return "quote": " ".join([str(arg) for arg in args])
    

fonte: Django Project Docs

Mesma coisa que 'simples', mas:

• o resultado é associado a uma variável de contexto em vez de aparecer diretamente na 'página'

ClassyTags

Templates em Django - Django4FrontEnd

from classytags.core import Tag, Options
from classytags.arguments import Argument
from django import template

register = template.Library()

class Hello(Tag):
    name = 'hello'
    options = Options(
        Argument('name'),
        'as',
        Argument('varname', required=False, resolve=False)
    )

    def render_tag(self, context, name, varname):
        output = 'hello %s' % name
        if varname:
            context[varname] = output
            return ''
        else:
            return output

register.tag(Hello)

ClassyTags

fonte: Django Classy Tags GitHub Repository 

Tag + Assignment Tag