python＆jinja2：执行预定义的过滤器列表

Question

Trying to do something like this:

filters = ['foo', 'bar']

And then in a Jinja2 template:

<p>{{value|filter for filter in filters}}</p>

Where foo and bar are Jinja2 filters I've defined.

This isn't working but it seems like it should be easy enough to accomplish. Any thoughts?

Answer 1

Assuming you're using flask (otherwise just adjust for however your filters are defined), you can just create a filter to apply the named filters.

In your filter definitions (eg my_filters.py ):

def filter1(x):
    return 'filtered1( {} )'.format(x)
app.jinja_env.filters['filter1'] = filter1 # Register filter

def filter2(x):
    return 'filtered2( {} )'.format(x)
app.jinja_env.filters['filter2'] = filter2

# Create a filter to apply a list of filters by name...
def apply_filters_by_name(x, filter_names):
    result = x
    # Loop through filter names and apply them sequentially
    for fname in filter_names: 
        # Get the filter function matching this name
        filter_function = app.jinja_env.filters[fname]

        # Apply the filter
        result = filter_function(result) # apply filter

    return result
app.jinja_env.filters['apply_filters_by_name'] = apply_filters_by_name

...so in your HTML template, for example:

{% set some_filter_names = ['filter1', 'filter2'] %}
{{ 'hello world'|apply_filters_by_name(some_filter_names) }}

Here, I've set some_filter_names inside the template but obviously you could also pass it in as a variable instead.

The result is:

filtered2( filtered1( hello world ) )