Filter dict keys based on their value

[baby-gnu]

Is your feature request related to a problem? Please describe.

I find uselessly difficult to manipulate multi-level dict and think that some filters may ease their manipulation and make the SLS more readable.

I usually define a dict in pillar or some yaml data file and want to filter the keys based on subkeys values, for example:

bigdict:
  top1:
    enabled: true
    descr: this is a top level item1
  top2:
    enabled: false
    descr: this is a top level item2

I may want:

• to get the key names of bigdict where enabled is true (or sometimes false)
• to get the object where enabled is true (or sometimes false)

Describe the solution you'd like

Sometimes I want only the key names:

{%- set bigdict = {'top1': {'enabled': false, 'descr': 'this is a top level item1'},
                   'top2': {'enabled': true, 'descr': 'this is a top level item2'}} %}

The enabled tops are {{ bigdict | FilterKeysValues("enabled") | FilterThatReturnJustTheKeyName | join(", ") }}

Sometime, I may want a subkey value:

{%- set bigdict = {'top1': {'enabled': false, 'descr': 'this is a top level item1'},
                   'top2': {'enabled': true, 'descr': 'this is a top level item2'}} %}

The enabled tops descriptions are:
- {{ bigdict | FilterKeysValues("enabled") | FilterThatReturnAqueryLikeTraverse(":descr") | join("\n- ") }}

The FilterThatReturnJustTheKeyName and FilterThatReturnAqueryLikeTraverse may be the same FilterTraverseLike, as an idea:

• FilterTraverseLike without any argument returns {'top1': {'enabled': false, 'descr': 'this is a top level item1'}}
• FilterTraverseLike(".") returns the top1 string
• FilterTraverseLike(":") returns {'enabled': false, 'descr': 'this is a top level item1'}
• FilterTraverseLike(":descr") returns 'this is a top level item1'

The FilterKeysValues should obviously have a proper name and may have a parameter like the FilterTraverseLike:

{%- set bigdict = {'top1': {'value': {'enabled': false, 'descr': 'this is a top level item1'}},
                   'top2': {'value': {'enabled': true, 'descr': 'this is a top level item2'}}} %}

The enabled tops are {{ bigdict | FilterKeysValues(":value:enabled") | FilterThatReturnAqueryLikeTraverse(".") | join(", ") }}

Describe alternatives you've considered

Actually, I'm writing quite a bunch of jinja to do it, for example:

{%- set bigdict = {'top1': {'enabled': false, 'descr': 'this is a top level item1'},
                   'top2': {'enabled': true, 'descr': 'this is a top level item2'}} %}
{%- set filtered = [] %}
{%- for k, v in bigdict.items() %}
{%-   if v.get('enabled', False) %}
{%-     do filtered.append(k) %}
{%-   endif %}
{%- endfor %}
The enabled tops are {{ filtered | join(',') }}

or

{%- set bigdict = {'top1': {'enabled': false, 'descr': 'this is a top level item1'},
                   'top2': {'enabled': true, 'descr': 'this is a top level item2'}} %}
The enabled tops descriptions are:
{%- for k, v in bigdict.items() %}
{%-   if v.get('enabled', False) %}
- {{ v.descr }}
{%-   endif %}
{%- endfor %}

Additional context

• This kind of new filters are not an option upstream.
• It may be related to Add a new jinja filter items #57970.

[baby-gnu]

Instead of doing magic on first argument, the returned values could be configurable with parameters:

• FilterTraverseLike without any argument returns {'top1': {'enabled': false, 'descr': 'this is a top level item1'}}
• FilterTraverseLike(key=True) returns the top1 string
• FilterTraverseLike(value=True) returns {'enabled': false, 'descr': 'this is a top level item1'}
• FilterTraverseLike(traverse=":descr") returns 'this is a top level item1'
• FilterTraverseLike(key=True, value=True) returns the tuple ('top1', {'enabled': false, 'descr': 'this is a top level item1'}) (this could be an implementation for Add a new jinja filter items #57970)
• FilterTraverseLike(key=True, traverse=":descr") returns the tuple ('top1', 'this is a top level item1')

And as writing this comment I found useful to be able to do:

• FilterTraverseLike(object=True) returns the object {_name: 'top1', 'enabled': false, 'descr': 'this is a top level item1'}

and this looks so promising to me that it could became a default behaviour ;-)

Regards.