迭代并格式化模板过滤器返回的字典

Question

I'm trying to display metadata about an image in my Django app. The metadata is read from the image's exif header and stored in a dictionary with the image as a key, and returned to the template with a filter. In my template, I display the images, and would like to display the formatted metadata for that image. So far I can only get it to display the dictionary for that image (eg {'key1': 'value', 'key2', 'value'} ). I would like it to look like key1: value, key2: value .

#template.html
{% block content %}
    {% for image in images %}
        {{ exif|get_item:image }}
            <p><img src="{{ image.image.url }}" width="500" style="padding-bottom:50px"/></p>
    {% endfor %}
{% endblock %}


#views.py
def image_display(request):
    images = image.objects.all()

    exif = {}
    for file in images:
        cmd = 'exiftool ' + str(file.image.url) + ' -DateTimeOriginal -Artist'
        exifResults = (subprocess.check_output(cmd)).decode('utf8').strip('\r\n')
        exif[file] = dict(map(str.strip, re.split(':\s+', i)) for i in exifResults.strip().splitlines() if i.startswith(''))

    context = {
        'images': images,
        'exif': exif,
    }

    @register.filter
    def get_item(dictionary, key):
        return dictionary.get(key)
    return render(request, 'image_display.html', context=context)

I thought I could just do {% for key, value in exif|get_item:image.items %} in the template, but that returns an error:

VariableDoesNotExist at /reader/image_display
Failed lookup for key [items] in <image: image1>

Is there a way I can either format the dictionary returned by the filter or iterate through it such that I can format each key and value pair?

Answer 1

As I see it, you are using this question's custom filter implementation: Django template how to look up a dictionary value with a variable but you need an extra step to format the specific key as it is a dictionary.

Why not create another filter that can return a dictionary formatted as you want?
Something like this:

@register.filter
def get_item_formatted(dictionary, key):
    tmp_dict = dictionary.get(key, None)
    if tmp_dict and isinstance(tmp_dict, dict):
        return [[t_key, t_value] for t_key, t_value in tmp_dict.items()]
    return None

This will return a list of lists of [key, value] pairs or None .
You can iterate through that in the template:

{% block content %}
    {% for image in images %}
        {% for pair in exif|get_item_formatted:image %}
            // Do what you need with the pair.0 (key) and pair.1 (value) here. 
        {% endfor %}
    {% endfor %}
{% endblock %}