7.2 标签和过滤器

Custom template tags and filters

https://docs.djangoproject.com/en/dev/howto/custom-template-tags/#howto-custom-template-tags

autoescape 自动转义

Controls the current auto-escaping behavior. This tag takes either on or off as an argument and that determines whether auto-escaping is in effect inside the block. The block is closed with an endautoescape ending tag.

When auto-escaping is in effect, all variable content has HTML escaping applied to it before placing the result into the output (but after any filters have been applied). This is equivalent to manually applying the escape filter to each variable.

The only exceptions are variables that are already marked as “safe” from escaping, either by the code that populated the variable, or because it has had the safe or escape filters applied.

Sample usage:

{% autoescape on %}
    {{ body }}
{% endautoescape %}

escape

scapes a string’s HTML. Specifically, it makes these replacements:

• < is converted to <
• > is converted to >
• ' (single quote) is converted to '
• " (double quote) is converted to "
• & is converted to &

Deprecated since version 1.10:

对应后台函数

from django.utils.safestring import mark_safe 

def mark_for_escaping(s):
    """
    Explicitly mark a string as requiring HTML escaping upon output. Has no
    effect on SafeData subclasses.

    Can be called multiple times on a single string (the resulting escaping is
    only applied once).
    """
    if hasattr(s, '__html__') or isinstance(s, EscapeData):
        return s
    if isinstance(s, bytes) or (isinstance(s, Promise) and s._delegate_bytes):
        return EscapeBytes(s)
    if isinstance(s, (six.text_type, Promise)):
        return EscapeText(s)
    return EscapeString(str(s))

safe

Marks a string as not requiring further HTML escaping prior to output. When autoescaping is off, this filter has no effect.

在django输出之前，要求不对字符串转义。当自动转义关闭的时候，这个过滤器失效。

对应在django后台的函数

from django.utils.safestring import mark_safe 

def mark_safe(s):
    """
    Explicitly mark a string as safe for (HTML) output purposes. The returned
    object can be used everywhere a string or unicode object is appropriate.

    Can be called multiple times on a single string.
    """
    if hasattr(s, '__html__'):
        return s
    if isinstance(s, bytes) or (isinstance(s, Promise) and s._delegate_bytes):
        return SafeBytes(s)
    if isinstance(s, (six.text_type, Promise)):
        return SafeText(s)
    return SafeString(str(s))

linebreaks 换行符

https://docs.djangoproject.com/en/1.11/ref/templates/builtins/#linebreaksbr

将换行符换成合成的HTML标签，新起一行用<br>，跟在一个空行后面则用</p>

Replaces line breaks in plain text with appropriate HTML; a single newline becomes an HTML line break (<br />) and a new line followed by a blank line becomes a paragraph break (</p>).

For example:

{{ value|linebreaks }}

If value is Joel\nis a slug, the output will be <p>Joel<br />is a slug</p>.

linebreaksbr

Converts all newlines in a piece of plain text to HTML line breaks (<br />).

For example:

{{ value|linebreaksbr }}

If value is Joel\nis a slug, the output will be Joel<br />is a slug.

@register.filter(is_safe=True, needs_autoescape=True)
@stringfilter
def linebreaksbr(value, autoescape=True):
    """
    Converts all newlines in a piece of plain text to HTML line breaks
    (``<br />``).
    """
    autoescape = autoescape and not isinstance(value, SafeData)
    value = normalize_newlines(value)
    if autoescape:
        value = escape(value)
    return mark_safe(value.replace('\n', '<br />'))

参考 django textfield 换行问题

tags

load

The {% load %} tag looks at your INSTALLED_APPS setting and only allows the loading of template libraries within installed Django applications.

extend

include

• DJANGO基础学习之转义总结：escape，autoescape，safe，mark_safe
• django中自定义标签和过滤器