[WARNING]: when statements should not include jinja2 templating delimiters - ansible

Question

I was wondering what is the correct syntax for when statements?
I have this playbook:
- set_fact:
sh_vlan_id: "{{ output.response|map(attribute='vlan_id')|list|join(',') }}"
- name: create vlans
ios_config:
provider: "{{ provider }}"
parents: vlan {{ item.id }}
lines: name {{ item.name }}
with_items: "{{ vlans }}"
register: result
when: '"{{ item.id }}" not in sh_vlan_id'
And, running it, gives me a warning but it still runs through. I am not sure if this is correct or not.
TASK [set_fact] ************************************************
ok: [acc_sw_01]
TASK [create vlans] ***********************************************
[WARNING]: when statements should not include jinja2 templating delimiters such as {{ }} or {% %}. Found: "{{ item.id }}" not in sh_vlan_id
skipping: [acc_sw_01] => (item={u'id': 10, u'name': u'voice-1'})
skipping: [acc_sw_01] => (item={u'id': 101, u'name': u'data-2'})
skipping: [acc_sw_01] => (item={u'id': 100, u'name': u'data-1'})
changed: [acc_sw_01] => (item={u'id': 11, u'name': u'voice-2'})
If I remove the curly braces around item.id in the when statement:
when: item.id not in sh_vlan_id
It gives me an error:
TASK [set_fact] ***************************************************
ok: [acc_sw_01]
TASK [create vlans] ***********************************************
fatal: [acc_sw_01]: FAILED! => {"failed": true, "msg": "The conditional check 'item.id not in sh_vlan_id' failed. The error was: Unexpected templating type error occurred on ({% if item.id not in sh_vlan_id %} True {% else %} False {% endif %}): coercing to Unicode: need string or buffer, int found\n\nThe error appears to have been in '/ansible/cisco-ansible/config_tasks/vlan.yml': line 16, column 3, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n\n- name: create vlans\n ^ here\n"}
I'm using ansible 2.3.0 (devel cbedc4a12a).

Answer 1

The correct syntax is to not include Jinja delimiters ({{ ... }}) as indicated by the warning. Your condition doesn't work otherwise because the types are not compatible.
You could try type coercion:
when: 'item.id | string not in sh_vlan_id'
See: https://jinja.palletsprojects.com/en/3.1.x/templates/#builtin-filters

Answer 2

Another example for reference ..
- name: Sudoers | update sudoers file and validate
lineinfile: "dest=/etc/sudoers
insertafter=EOF
line='{{ item.username }} ALL=(ALL) NOPASSWD: ALL'
regexp='^{{ item.username }} .*'
state=present"
when: '{{ item.use_sudo }} == True'
with_items: '{{users}}'
I was getting below orning.
[WARNING]: conditional statements should not include jinja2 templating delimiters such as {{ }} or {% %}. Found: "{{ item.use_sudo}}" == True
After making the below changes into the playbook it works fine.
- name: Sudoers | update sudoers file and validate
lineinfile: "dest=/etc/sudoers
insertafter=EOF
line='{{ item.username }} ALL=(ALL) NOPASSWD: ALL'
regexp='^{{ item.username }} .*'
state=present"
when: 'item.use_sudo|bool'
with_items: '{{users}}'
UPD: if you use variable type boolean that == True not need

Answer 3

Braces must be removed when calling a variable in a when clause.
In this example, we install the urbackup client only if it is not already installed or if the version already present is different from the version contained in the variable.
urbackup_client_version is a variable defined in the playbook:
vars:
- urbackup_client_version: 2.5.22
then we check in a role if urbackup is already installed.
- name: Is UrBackup already installed?
shell: urbackupclientctl --version
register: urbackup_enable
failed_when: urbackup_enable.rc != 1 and urbackup_enable.rc != 127
It is necessary to position the variable with braces in the wget command but you have to remove them in the when clause:
- name: UrBackup client installation
shell: 'TF=$(mktemp) && wget "https://hndl.urbackup.org/Client/latest/UrBackup%20Client%20Linux%20{{urbackup_client_version}}.sh" -O $TF && sudo sh $TF; rm -f $TF'
when:
- action == 'install'
- urbackup_enable.rc == 127 or (urbackup_enable.rc == 1 and urbackup_client_version not in urbackup_enable.stdout)