jinja-comprehensions

Jinja2 environments providing support for list/dict comprehensions, set literals/comprehensions, generator expressions, and list/dict spreading.

Set literals

{{ {'set', 'set', 'literal', 'literal'} }}

{'literal', 'set'}

Comprehensions

list: {{ [n // 2 for n in range(10)] }}
set:  {{ {n // 2 for n in range(10)} }}
dict: {{ {n: n // 2 for n in range(10)} }}

list: [0, 0, 1, 1, 2, 2, 3, 3, 4, 4]
set:  {0, 1, 2, 3, 4}
dict: {0: 0, 1: 0, 2: 1, 3: 1, 4: 2, 5: 2, 6: 3, 7: 3, 8: 4, 9: 4}

Generator expressions

{{ (n // 2 for n in range(10)) | join(', ') }}

0, 0, 1, 1, 2, 2, 3, 3, 4, 4

List/dict spreading

{% set stuff = {'b': 98, 'c': 99, 'd': 100} -%}
{{ {'a': 97, **stuff, 'e': 101} }}
{{ [97, *stuff.values(), 101] }}

{'a': 97, 'b': 98, 'c': 99, 'd': 100, 'e': 101}
[97, 98, 99, 100, 101]

Environments are provided for both sync and async contexts, as well as native variants, too.

Quickstart

pip install jinja-comprehensions

And use a ComprehensionEnvironment (or NativeComprehensionEnvironment) instead of the vanilla jinja2.Environment to compile your templates:

# For rendering to strings
from jinja_comprehensions import ComprehensionEnvironment
jinja_env = ComprehensionEnvironment()

# For rendering to native types
from jinja_comprehensions import NativeComprehensionEnvironment
jinja_env = NativeComprehensionEnvironment()

# For rendering to native types with async enabled
#  (This env avoids some pitfalls with vanilla Jinja2 native envs and Awaitable return values)
from jinja_comprehensions import NoLiteralEvalComprehensionNativeEnvironment
jinja_env = NoLiteralEvalComprehensionNativeEnvironment()