timetracker/filter-design.md

Django

Session.objects.filter(timestamp_start__year=2024)

JSON

{
    "type": "session_start",
    "operator": "equals",
    "value": "2024"
}

HTML

<select name="filters">
    <option value='[{"type": "session_start", "operator": "equals", "value": "2024"}]'>2024</option>
    <option value='[{"type": "session_start", "operator": "equals", "value": "2023"}]'>2023</option>
</select>

Python: Python -> HTML

filters = [
    {
        "type": "session_start",
        "operator": "equals",
        "value": "2024"
    }
]

# predefined values
session_start_select = Select(name="filters", children=session_start_options)
session_start_options = [
    Option(value=create_filter("session_start", "equals", value=year))
    for year in range(2000, 2024)
]

# user-selected values

Python: JSON -> Django

filter_types = {
    "session_start": {
        "equals": "timestamp_start__exact=",
        "isnull": "timestamp_start__exact=None",
        "greater_than": "timestamp_start__gt=",
        "less_than": "timestamp_start__lt=",
    },
}
# filter_string = request.GET.get("filters")
filter_string = """
{
    "type": "session_start",
    "operator": "equals",
    "value": "2024"
}
"""
def string_to_django_filter_dict(s: str):
    if s[-1] == "=":
        s + value
    key, value = s.split("=")
    return {key: value}
    
filter_obj = json.loads(filter_string)[0]
field, operator, value = filter_obj

if type in filter_types:
    if operator in filter_types[type]:
        queryset.filter(Q(**string_to_django_filter_dict(filter_types[type][operator])}))
    else:
        return False

Python: Django -> JSON -> URI param

filters = [
    {
        "type": "session_start",
        "operator": "equals",
        "value": "2024"
    }
]
context = {
    "filters": json.dumps(filters)
}
return render("filter.html", context)

Python: Django -> JSON (function)

create_filter("session_start", "operator": "equals", "value": "2024")