my variable file/data (i get this info from other source)

final_lst:

[
  {
    "service_role": "do_not_use",
    "first_ip": "10.7.17.1",
    "last_ip": "10.7.16.9",
    "uid": "do_not_use"
  },
  {
    "service_role": "role_a",
    "first_ip": "10.7.17.10",
    "last_ip": "10.7.17.25",
    "uid": "role_a_range_01"
  },
  {
    "service_role": "role_a",
    "first_ip": "10.7.17.56",
    "last_ip": "10.7.17.70",
    "uid": "role_a_range_02"
  }
]

test.j2:

{%- for item in final_lst %}
sr: {{item.service_role}}
ip: {{item.first_ip}}
{%- endfor -%}

my code: from jinja2 import Template , Environment, FileSystemLoader

env = Environment(loader=FileSystemLoader('templates'),)
int_template = env.get_template('test.j2')     

out = int_template.render(final_lst=final_lst)
print(out)

result:

sr: do_not_use
ip: 10.7.17.1
sr: role_a
fip: 10.7.17.10
sr: role_a
fip: 10.7.17.56

what i want to print is in json format like below

desired output:

[
  {
    "sr": "do_not_use",
    "fip": "10.7.17.1"
  },
  {
    "sr": "role_a",
    "fip": "10.7.17.10"
  },
  {
    "sr": "role_a",
    "fip": "10.7.17.56"
  }
]

i have a requirement to generate above output via jinja2 template. how can i get json format output anything that is rendered from jinja2 template

CodePudding user response：

I'd suggest not to generate json with means of template language. It is slower and much more error prone.

In your python code:

import json
from jinja2 import Template, Environment, FileSystemLoader

data = [
  {
    "service_role": "do_not_use",
    "first_ip": "10.7.17.1",
    "last_ip": "10.7.16.9",
    "uid": "do_not_use"
  },
  {
    "service_role": "role_a",
    "first_ip": "10.7.17.10",
    "last_ip": "10.7.17.25",
    "uid": "role_a_range_01"
  },
  {
    "service_role": "role_a",
    "first_ip": "10.7.17.56",
    "last_ip": "10.7.17.70",
    "uid": "role_a_range_02"
  }
]
data = [
    {
        'sr': elem['service_role'],
        'fip': elem['first_ip'],
    }
    for elem in data
]
data_dump = json.dumps(data, indent=2)

env = Environment(loader=FileSystemLoader('templates'),)
int_template = env.get_template('test.j2')     

out = int_template.render(data_dump=data_dump)
print(out)

In your template (test.j2):

{{ data_dump }}

Don't do this!

If you insist on template solution:

[
  {% for item in final_lst %}
  {{ '{' }}
    "sr": "{{ item.service_role }}",
    "ip": "{{ item.first_ip }}"
  {{ '}' }}
  {% endfor %}
]

You can replace {% with {%- back to get compact representation (same applies to json.dumps, just get rid of indent parameter).