feat: Remove slug field from ResearchStudy model and update related references

generic/templatetags/help_tags.py

@@ -3,6 +3,27 @@ from django.template import Node, TemplateSyntaxError, Variable
 
 register = template.Library()
 
+
+@register.simple_tag(takes_context=True)
+def update_query_param(context, key, value):
+    """Return a querystring with a dynamic key updated.
+
+    Django's built-in querystring tag does not allow dynamic keyword names,
+    so this helper keeps compatibility for django-tables2 prefixed fields.
+    """
+    request = context.get("request")
+    if request is None:
+        return ""
+
+    params = request.GET.copy()
+    if value in (None, ""):
+        params.pop(key, None)
+    else:
+        params[key] = value
+
+    encoded = params.urlencode()
+    return f"?{encoded}" if encoded else ""
+
 class HelpNode(Node):
     def __init__(self, nodelist, title, icon, extra_class):
         self.nodelist = nodelist