{
  "posts": [
    {"city": "Vienna", "text": "First post in Vienna"},
    {"city": "London", "text": "First post in London"},
    {"city": "Vienna", "text": "Second post in Vienna"},
    {"city": "vienna", "text": "First post in lowercase Vienna"},
    {"text": "no city!?"}
  ]
}
---
{%- for city, posts in posts|groupby("city", default="No City") %}
  - {{ city }}:
    {%- for post in posts %}
    - {{ post.text }}
    {%- endfor %}
{%- endfor %}
--
{%- for group in posts|groupby(attribute="city", case_sensitive=true) %}
  - {{ group.grouper }}:
    {%- for post in group.list %}
    - {{ post.text }}
    {%- endfor %}
{%- endfor %}
--
{{ (posts|groupby("city", default="AAA"))[0] }}