# Loopless alternative? **URL:** \ **Category:** Ansible Project\ **Created:** [August 16, 2023, 2:52pm UTC](https://forum.ansible.com/t/loopless-alternative/38341 "2023-08-16T14:52:34Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![dnmvisser](https://avatars.discourse-cdn.com/v4/letter/d/8e8cbc/32.png) [@dnmvisser](https://forum.ansible.com/u/dnmvisser)\ **Post date:** [August 16, 2023, 2:52pm UTC](https://forum.ansible.com/t/loopless-alternative/38341/1 "2023-08-16T14:52:34Z")
Hii I have a list of dicts, where I want to inject a number of helper keys. I can do this with set\_facts in a loop. Example playbook (hopefully this displays OK): ---
**Author:** ![utoddl](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/utoddl/32/249_2.png) [@utoddl](https://forum.ansible.com/u/utoddl)\ **Post date:** [August 16, 2023, 7:17pm UTC](https://forum.ansible.com/t/loopless-alternative/38341/2 "2023-08-16T19:17:25Z")
Here’s the best I’ve got to offer. I tried pipelining filters etc but couldn’t quite get over the hump. So, back to old school loops. ```auto - set_fact: backup_objects: | {% set result = [] %} {% for obj in all_objects %} {% set _ = result.append({'basename': obj['Key'] | regex_replace('^' ~ prefix ~ '\d{10}_(.*)\.pgdump', '\1')} | combine(obj)) %} {% endfor %}{{ result }} ``` The point of the “set \_” line is for the side effect of appending revised objects to the “result” list. Otherwise it’s pretty straightforward. Cheers, ---
**Author:** ![vbotka](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/vbotka/32/359_2.png) [@vbotka](https://forum.ansible.com/u/vbotka)\ **Post date:** [August 16, 2023, 10:46pm UTC](https://forum.ansible.com/t/loopless-alternative/38341/3 "2023-08-16T22:46:08Z")
Create the list of the hashes   bn\_regex: '^{{ prefix }}\d{10}\_(.\*)\.pgdump$'   bn: "{{ all\_objects|           map(attribute='Key')|           map('regex\_replace', bn\_regex, '\\1')|           map('community.general.dict\_kv', 'basename') }}" gives   bn:   - basename: dev\_wss\_db   - basename: dev\_wss\_db\_requests   - basename: dev\_bss\_service\_database   - basename: dev\_bss\_frontend\_db   - basename: dev\_mss\_db zip the lists and combine the items   backup\_object: "{{ all\_objects|zip(bn)|map('combine') }}" ---
**Author:** ![vbotka](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/vbotka/32/359_2.png) [@vbotka](https://forum.ansible.com/u/vbotka)\ **Post date:** [August 16, 2023, 11:34pm UTC](https://forum.ansible.com/t/loopless-alternative/38341/4 "2023-08-16T23:34:26Z")
There are options. Filter \*basename\* and get rid of \*prefix\*   bn\_regex: '^\d{10}\_(.\*)\.pgdump$'   bn: "{{ all\_objects|           map(attribute='Key')|           map('basename')|           map('regex\_replace', bn\_regex, '\\1')|           map('community.general.dict\_kv', 'basename') }}" Create the hash in \*regex\_replace\* and use \*from\_yaml\* instead of \*community.general.dict\_kv\*   bn: "{{ all\_objects|           map(attribute='Key')|           map('basename')|           map('regex\_replace', bn\_regex, '{basename: \\1}')|           map('from\_yaml') }}" Instead of \*regex\_replace\* use \*splitext\* and \*split\*   bn: "{{ all\_objects|           map(attribute='Key')|           map('basename')|           map('splitext')|map('first')|           map('split', '\_', 1)|map('last')|           map('community.general.dict\_kv', 'basename') }}" ---
**Author:** ![utoddl](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/utoddl/32/249_2.png) [@utoddl](https://forum.ansible.com/u/utoddl)\ **Post date:** [August 17, 2023, 11:56am UTC](https://forum.ansible.com/t/loopless-alternative/38341/5 "2023-08-17T11:56:58Z")
Thanks, Vladimir. I had missed the point of “community.general.dict\_kv”. I had gotten as far as this: ```auto - set_fact: bn: | {{ query('ansible.builtin.nested', ['basename'], (all_objects > map(attribute='Key') > map('regex_replace', '^' ~ prefix ~ '\d{10}_(.*)\.pgdump', ''))) }} ``` which produces: ```auto bn: - - basename - dev_wss_db - - basename - dev_wss_db_requests - - basename - dev_bss_service_database - - basename - dev_bss_frontend_db - - basename - dev_mss_db ``` But I didn’t find a way to map that using “community.general.dict” to create ```auto bn: - basename: dev_wss_db - basename: dev_wss_db_requests - basename: dev_bss_service_database - basename: dev_bss_frontend_db - basename: dev_mss_db ``` This for me is one of the more frustrating things about Jinja pipelines. I keep wishing “map” would take arbitrary expressions rather than the limited set it’s stuck with. So you end up with a fleet of one-off filters like “community.general.dict\_kv” which does what “community.general.dict” would do if there were an obvious way to turn this: ```auto - - basename - dev_wss_db - - basename - dev_wss_db_requests - - basename - dev_bss_service_database - - basename - dev_bss_frontend_db - - basename - dev_mss_db ``` into this: ```auto - - - basename - dev_wss_db - - - basename - dev_wss_db_requests - - - basename - dev_bss_service_database - - - basename - dev_bss_frontend_db - - - basename - dev_mss_db ``` i.e. a “deepen” counterpart to “flatten”. But that magical incantation has so far eluded me. ---
**Author:** ![vbotka](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/vbotka/32/359_2.png) [@vbotka](https://forum.ansible.com/u/vbotka)\ **Post date:** [August 17, 2023, 3:07pm UTC](https://forum.ansible.com/t/loopless-alternative/38341/6 "2023-08-17T15:07:40Z")
>    bn: >    - - basename >      - dev\_wss\_db >    - - basename >      - dev\_wss\_db\_requests >    - - basename >      - dev\_bss\_service\_database >    - - basename >      - dev\_bss\_frontend\_db >    - - basename >      - dev\_mss\_db > > But I didn't find a way to map that using "community.general.dict" to create > >    bn: >    - basename: dev\_wss\_db >    - basename: dev\_wss\_db\_requests >    - basename: dev\_bss\_service\_database >    - basename: dev\_bss\_frontend\_db >    - basename: dev\_mss\_db You can always use brute-force Jinja as the last resort. For example, given the list   bn\_list:   - dev\_wss\_db   - dev\_wss\_db\_requests   - dev\_bss\_service\_database   - dev\_bss\_frontend\_db   - dev\_mss\_db the below Jinja creates the list of the hashes   bn: |     {% filter from\_yaml %}     {% for basename in bn\_list %}     - basename: {{ basename }}     {% endfor %}     {% endfilter %} As a side-note, this is equivalent to   bn: "{{ all\_objects|           map(attribute='Key')|           map('regex\_replace', bn\_regex, '{basename: \\1}')|           map('from\_yaml') }}" > This for me is one of the more frustrating things about Jinja > pipelines. I keep wishing "map" would take arbitrary > expressions rather than the limited set it's stuck with. This is very good point. It would be possible to write such a filter. However, I'm not sure about the security implications. ---
**Author:** ![system](https://us1.discourse-cdn.com/ansible/original/1X/1882d9a01da5d8996a862359b0913cc568a39b84.svg) [@system](https://forum.ansible.com/u/system)\ **Post date:** [August 17, 2023, 5:11pm UTC](https://forum.ansible.com/t/loopless-alternative/38341/7 "2023-08-17T17:11:25Z")
see map/select/reject filters .. they are actually loops and normally much simpler than using jinja command syntax ( {% %} ). ---
**Author:** ![vbotka](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/vbotka/32/359_2.png) [@vbotka](https://forum.ansible.com/u/vbotka)\ **Post date:** [August 17, 2023, 6:29pm UTC](https://forum.ansible.com/t/loopless-alternative/38341/8 "2023-08-17T18:29:44Z")
Unfortunately, some filters are not \*map\* friendly. For example, the filter \*product\*   list1|product(list2) .............. works fine   list1|zip(list2)|map('product') ... does not work Details: Given the list   l1:     - dir: /tmp/test/d1       sub\_dir: [a, b]     - dir: /tmp/test/d2       sub\_dir: [a, b, c] the goal is to create the list of products   l2:   - /tmp/test/d1/a   - /tmp/test/d1/b   - /tmp/test/d2/a   - /tmp/test/d2/b   - /tmp/test/d2/c The iteration (the filter \*subelements\* not used to demonstrate the functionality of \*product\*)     - debug:         msg: "{{ [item.0]|product(item.1) }}"       loop: "{{ dirs|zip(sdirs) }}"       vars:         dirs: "{{ l1|map(attribute='dir') }}"         sdirs: "{{ l1|map(attribute='sub\_dir') }}" works as expected. Gives (abridged)   msg:   - - /tmp/test/d1     - a   - - /tmp/test/d1     - b   msg:   - - /tmp/test/d2     - a   - - /tmp/test/d2     - b   - - /tmp/test/d2     - c But, the filter \*product\* doesn't work with \*map\*   dirs: "{{ l1|map(attribute='dir') }}"   sdirs: "{{ l1|map(attribute='sub\_dir') }}"   l3: "{{ dirs|zip(sdirs)|map('product') }}" gives   l3:   - - - /tmp/test/d1     - - - a         - b   - - - /tmp/test/d2     - - - a         - b         - c This leaves you with Jinja if you want to avoid the loops in tasks   l3: |     {% filter from\_yaml %}     {% for i in l1 %}     {% for s in i.sub\_dir %}     - {{ i.dir }}/{{ s }}     {% endfor %}     {% endfor %}     {% endfilter %} ---
**Author:** ![dnmvisser](https://avatars.discourse-cdn.com/v4/letter/d/8e8cbc/32.png) [@dnmvisser](https://forum.ansible.com/u/dnmvisser)\ **Post date:** [August 18, 2023, 1:34pm UTC](https://forum.ansible.com/t/loopless-alternative/38341/9 "2023-08-18T13:34:49Z")
I ended up with the inline jinja for loop. Also I used a pipe lookup instead of an s3 list task prior to this one. So now everything is done in a one single task, without noise, and with the same results. Thanks everyone, it was really useful and I will keep it in mind for future reference. Dick