feat: added portal page to join a cohort

Issue #271

school/www/cohorts/join.py

@@ -0,0 +1,24 @@
+import frappe
+from . import utils
+
+def get_context(context):
+    context.no_cache = 1
+
+    course = utils.get_course(frappe.form_dict["course"])
+    cohort = course and utils.get_cohort(course, frappe.form_dict["cohort"])
+    subgroup = cohort and utils.get_subgroup(cohort, frappe.form_dict["subgroup"])
+    if not subgroup:
+        context.template = "www/404.html"
+        return
+
+    invite_code = frappe.form_dict["invite_code"]
+    if subgroup.invite_code != invite_code:
+        context.template = "www/404.html"
+        return
+
+    utils.add_nav(context, "All Courses", "/courses")
+    utils.add_nav(context, course.title, "/courses/" + course.name)
+
+    context.course = course
+    context.cohort = cohort
+    context.subgroup = subgroup