Select and concatenate dict value lists - ansible

Question

I've got a dict of lists like this:
packages:
server:
- foo
- bar
- baz
client:
- spam
- ham
- eggs
runtime:
- corge
- grault
- garply
and I want to generate a list by defining keys to select in another dict, so e.g.:
enable:
server: true
client: false
runtime: true
would result in:
output:
- foo
- bar
- baz
- corge
- grault
- garply
Any ideas how to do this in ansible/jinja?? Ideally without using the loop construct but I could live with that. I suspect it'll need an intermediate variable and so far all I've got is something to extract a list of the keys from enable which have a true value:
- set_fact:
enabled: "{{ (enable | dict2items | selectattr('value') | list | items2dict).keys() }}"
If this looks a bit convoluted its because both packages and enable are existing role variables which I'd prefer not to change. But open to suggestions (especially on packages) if reshaping them makes this much easier.

Answer 1

Let's create the list of enabled hosts first. For example
- set_fact:
my_hosts: "{{ enable|dict2items|
selectattr('value')|
map(attribute='key')|list }}"
- debug:
var: my_hosts
give
my_hosts:
- server
- runtime
Then use this list to extract the packages. For example
- set_fact:
my_list: "{{ my_hosts|map('extract', packages)|list|flatten }}"
- debug:
var: my_list
give
my_list:
- foo
- bar
- baz
- corge
- grault
- garply
The single task below comprises both steps
- set_fact:
my_list: "{{ my_hosts|map('extract', packages)|list|flatten }}"
vars:
my_hosts: "{{ enable|dict2items|
selectattr('value')|
map(attribute='key')|list }}"