# merging lists **URL:** \ **Category:** Ansible Project\ **Created:** [April 17, 2023, 10:22pm UTC](https://forum.ansible.com/t/merging-lists/37896 "2023-04-17T22:22:10Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![mdidomenico](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@mdidomenico](https://forum.ansible.com/u/mdidomenico)\ **Post date:** [April 17, 2023, 10:22pm UTC](https://forum.ansible.com/t/merging-lists/37896/1 "2023-04-17T22:22:10Z")
i want to do this, but i'm not getting exactly what i want lista: - { one: 'str1', two: 'str2' } listb: - "{{ lookup('vars','lista') }}" - { one: 'str1', two: 'str2' } the output i want is listb: { one: 'str1', two: 'str2' }, { one: 'str1', two: 'str2' } but what i get is listb: [{ one: 'str1', two: 'str2' }], { one: 'str1', two: 'str2' } is there a way to merge the two lists? ---
**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:** [April 17, 2023, 11:05pm UTC](https://forum.ansible.com/t/merging-lists/37896/2 "2023-04-17T23:05:28Z")
The lookup \*vars\* is not necessary. Reference the variable   listb:     - "{{ lista }}"     - {one: str1, two: str2} You should get   listb:     - - one: str1         two: str2     - one: str1       two: str2 This is correct. The first item on the list \*listb\* is list \*lista\*. If you put two items into the list \*lista\*   lista:     - one: str1       two: str2     - ccc: str3       ddd: str4 you'll get   listb:     - - one: str1         two: str2       - ccc: str3         ddd: str4     - one: str1       two: str2 You can \*flatten\* the list    listc: "{{ listb|flatten }}" gives   listc:     - one: str1       two: str2     - ccc: str3       ddd: str4     - one: str1       two: str2 However, a simpler option is adding lists. For example, given two lists   lista:     - {one: str1, two: str2}     - {ccc: str3, ddd: str4}   listb:     - {one: str1, two: str2} Declare the list \*listc\*. This will merge the two lists   listc: "{{ lista + listb }}" ---
**Author:** ![mdidomenico](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@mdidomenico](https://forum.ansible.com/u/mdidomenico)\ **Post date:** [April 17, 2023, 11:29pm UTC](https://forum.ansible.com/t/merging-lists/37896/3 "2023-04-17T23:29:02Z")
thanks for the help, but that's not exactly what i am after. i'm attempting to avoid creating a third variable. but maybe that's the only way ---
**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:** [April 18, 2023, 5:00am UTC](https://forum.ansible.com/t/merging-lists/37896/4 "2023-04-18T05:00:22Z")
> thanks for the help, but that's not exactly what i am after. i'm > attempting to avoid creating a third variable. but maybe that's the > only way You can avoid the third variable if you want to. For example,   b: "{{ a + [4, 5, 6] }}" will add the lists   b: [1, 2, 3, 4, 5, 6] ---
**Author:** ![dnmvisser](https://avatars.discourse-cdn.com/v4/letter/d/8e8cbc/32.png) [@dnmvisser](https://forum.ansible.com/u/dnmvisser)\ **Post date:** [April 18, 2023, 8:37am UTC](https://forum.ansible.com/t/merging-lists/37896/5 "2023-04-18T08:37:34Z")
If lista will only ever contain a single item, then listb could be just listb: - “{{ lista[0] }}” - { one: ‘str1’, two: ‘str2’ } ---
**Author:** ![Walter\_Rowe](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/walter_rowe/32/4506_2.png) [@Walter\_Rowe](https://forum.ansible.com/u/Walter_Rowe)\ **Post date:** [April 18, 2023, 12:56pm UTC](https://forum.ansible.com/t/merging-lists/37896/6 "2023-04-18T12:56:51Z")
---
**Author:** ![mdidomenico](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@mdidomenico](https://forum.ansible.com/u/mdidomenico)\ **Post date:** [April 18, 2023, 1:07pm UTC](https://forum.ansible.com/t/merging-lists/37896/7 "2023-04-18T13:07:30Z")
i got to this point as well in my testing, but the double list expansion of listb is a problem. ---
**Author:** ![Walter\_Rowe](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/walter_rowe/32/4506_2.png) [@Walter\_Rowe](https://forum.ansible.com/u/Walter_Rowe)\ **Post date:** [April 18, 2023, 1:08pm UTC](https://forum.ansible.com/t/merging-lists/37896/8 "2023-04-18T13:08:52Z")
This isn’t a double expansion of listb. lista and listb happen to have the same values. change one of them and run the playbook to prove it. Walter ---
**Author:** ![Walter\_Rowe](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/walter_rowe/32/4506_2.png) [@Walter\_Rowe](https://forum.ansible.com/u/Walter_Rowe)\ **Post date:** [April 18, 2023, 1:10pm UTC](https://forum.ansible.com/t/merging-lists/37896/9 "2023-04-18T13:10:46Z")
**% cat foo.yml** ---
**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:** [April 18, 2023, 2:40pm UTC](https://forum.ansible.com/t/merging-lists/37896/10 "2023-04-18T14:40:40Z")
Also, by using the sum() filter: ```auto [utoddl@tango ansible]$ cat foo.yml --- - name: test lists become: false gather_facts: false hosts: localhost vars: list_12: - { one: 'str1', two: 'str2' } list_34: - { three: 'str3', four: 'str4' } list_56: - { five: 'str5', six: 'str6' } tasks: - debug: msg="[{{ list_12, list_34, list_56 }}]" - debug: msg="{{ [list_12, list_34, list_56] | sum(start=[]) }}" [utoddl@tango ansible]$ ansible-playbook foo.yml PLAY [test lists] *************************************************************** TASK [debug] ******************************************************************** ok: [localhost] => { "msg": [ [ [ { "one": "str1", "two": "str2" } ], [ { "four": "str4", "three": "str3" } ], [ { "five": "str5", "six": "str6" } ] ] ] } TASK [debug] ******************************************************************** ok: [localhost] => { "msg": [ { "one": "str1", "two": "str2" }, { "four": "str4", "three": "str3" }, { "five": "str5", "six": "str6" } ] } PLAY RECAP ********************************************************************** localhost : ok=2 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0 ``` ---
**Author:** ![Walter\_Rowe](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/walter_rowe/32/4506_2.png) [@Walter\_Rowe](https://forum.ansible.com/u/Walter_Rowe)\ **Post date:** [April 18, 2023, 2:43pm UTC](https://forum.ansible.com/t/merging-lists/37896/11 "2023-04-18T14:43:01Z")
Brilliant! Walter ---
**Author:** ![mdidomenico](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@mdidomenico](https://forum.ansible.com/u/mdidomenico)\ **Post date:** [April 18, 2023, 3:01pm UTC](https://forum.ansible.com/t/merging-lists/37896/12 "2023-04-18T15:01:40Z")
agreed, brillant. i'll give that a whirl, but it looks like exactly what i'm after. thanks ---
**Author:** ![Walter\_Rowe](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/walter_rowe/32/4506_2.png) [@Walter\_Rowe](https://forum.ansible.com/u/Walter_Rowe)\ **Post date:** [April 18, 2023, 4:44pm UTC](https://forum.ansible.com/t/merging-lists/37896/13 "2023-04-18T16:44:03Z")
I just tested and this also works. - debug: msg=“{{ [listb] | sum(start=lista) }}” Walter ---
**Author:** ![Walter\_Rowe](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/walter_rowe/32/4506_2.png) [@Walter\_Rowe](https://forum.ansible.com/u/Walter_Rowe)\ **Post date:** [April 18, 2023, 4:46pm UTC](https://forum.ansible.com/t/merging-lists/37896/14 "2023-04-18T16:46:31Z")
And if you really wanted only unique list items this also works … - debug: msg=“{{ [listb] | sum(start=lista) **| unique** }}” Walter ---
**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:** [April 18, 2023, 5:12pm UTC](https://forum.ansible.com/t/merging-lists/37896/15 "2023-04-18T17:12:11Z")
Isn't \*flatten\* simpler?       - debug: msg="{{ [list\_12, list\_34, list\_56] | flatten }}"