README#

jinjyaml#

Application specific tag of Jinja2 template in PyYAML.

It may be useful if you only want to render special tag nodes in the document, instead of whole YAML string as a template.

Usage#

Example 1#

Add Jinja2 template constructor for tag "!j2"

import yaml
import jinjyaml as jy

ctor = jy.Constructor()
yaml.add_constructor("!j2", ctor, yaml.SafeLoader)

create YAML file 1.yml, with such contents:

array: !j2 |
  {% for i in range(n) %}
  - sub{{i}}: {{loop.index}}
  {% endfor %}

load and render the YAML file

with open("1.yml") as fp:
    data = yaml.load(fp, Loader=yaml.SafeLoader)
    # or for the short:
    # data = yaml.safe_load(fp)

jy.extract(data, context={"n": 3}, inplace=True)

print(data)

We’ll get:

{"array": [{"sub0": 1}, {"sub1": 2}, {"sub2": 3}]}

Example 2#

We have such YAML files:

sub-1.yml:
```
"1.1": one
"1.2": two
```

sub-2.yml:

"2.1":
  "2.1.1": three
  "2.1.2": four

main.yml:

foo: !j2 |

  {% filter indent %}
  {% include "sub-1.yml" %}
  {% endfilter %}

  {% filter indent %}
  {% include "sub-2.yml" %}
  {% endfilter %}

execute python code:

from pprint import pprint

import jinja2
import jinjyaml as jy
import yaml

env = jinja2.Environment(loader=jinja2.FileSystemLoader("."))

ctor = jy.Constructor()
yaml.add_constructor("!j2", ctor, yaml.SafeLoader)

with open("main.yml") as fp:
    doc = yaml.safe_load(fp)

obj = jy.extract(doc, env)
pprint(obj)

We’ll get:

{"foo": {"1.1": "one",
         "1.2": "two",
         "2.1": {"2.1.1": "three", "2.1.2": "four"}}}

NOTE:

Since Jinja2’s include and indent do not work very nice with indention languages like Python or YAML, it’s not advised to use the feature in a complex case.