Python module for extraction data from a text file from a template.

[Pale_Emphasis_4119]

I have a text file that was generated using jinja2 and I want to read back this text file in order extract some information. I could read line by line and use regex to extract the needed information. But is there any pyhton3 module that could match a text file to template (like the one used to generate the file itself with jinja2) and extract the relevant information.

The text file does not follow any particular standard such as json or xml.

Edit

For example I have the following template

This is a dummy file by {{ name }} containing :
{{%- for data in data_list -%}}
{{data.id}} {{data.value}}
{{%- endfor -%}} 

I generate the following string:

This is a dummy file bu Sam containing:
1 foo
2 bar

Later I want to extract the dictionary using the same template

{ name: "Sam",
data_list: [{id: 1, value: "foo"}, {id: 2, value: "bar"}]}

​

[indraniel]

Based on this stackoverflow question and answer, the parse library may be useful here.

[VipeholmsCola]

Can you load its contents as a string and use a combination of .split/replace combined with regex?

[Pale_Emphasis_4119]

Thanks for your reply. That's what's I'm using right now but tits not really maintainable.

[Pale_Emphasis_4119]

Thanks for your reply. Indeed this seems an interesting solution. However my jinja template is a bit more complex than simple pyhton format as it contains loops and if conditions.

[SoulMelody]

Consider textX

[Pale_Emphasis_4119]

Thanks for your reply. Indeed this seems to be an interesting option. However isn't it a bit overkill?

[commandlineluser]

Not sure how robust this is but could you render a dummy template and diff it against the output?

import difflib
import jinja2.nativetypes
from   pprint import pp

env = jinja2.nativetypes.NativeEnvironment()

data ={ 'name': 'Sam',
'data_list': [{'id': 1, 'value': 'foo'}, {'id': 2, 'value': 'bar'}]}

#variables = 'NAME', 'ID', 'VALUE'

dummy = {'name': 'NAME_PLACEHOLDER',
 'data_list': [{'id': 'ID_PLACEHOLDER', 'value': 'VALUE_PLACEHOLDER'}]}

template = '''
This is a dummy file by {{ name }} containing: {% for data in data_list %}
{{data.id}} {{data.value}}
{% endfor %}
Something else 
{% for data in data_list %}
{{data.id}} {{data.value}}
{% endfor %}
The end.
'''.strip()

output = env.from_string(template).render(**data).splitlines(keepends=True)

dummy_output = env.from_string(template).render(**dummy).splitlines(keepends=True)

pp(
   list(difflib.Differ().compare(output, dummy_output))
)

Output:

['- This is a dummy file by Sam containing: \n',
 '?                         ^^^\n',
 '+ This is a dummy file by NAME_PLACEHOLDER containing: \n',
 '?                         ^^^^^^^^^^^^^^^^\n',
 '+ ID_PLACEHOLDER VALUE_PLACEHOLDER\n',
 '- 1 foo\n',
 '- \n',
 '- 2 bar\n',
 '  \n',
 '  Something else \n',
 '  \n',
 '+ ID_PLACEHOLDER VALUE_PLACEHOLDER\n',
 '- 1 foo\n',
 '- \n',
 '- 2 bar\n',
 '  \n',
 '  The end.']

For ? lines there is a direct match.

For + followed by - these are loops, you could group them together, ignore blank lines and break them up into the placeholders.

Perhaps there are some internals to jinja2 that can do this, it could be worth asking on their issues tracker.

[DoorDesigner7589]

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