Choose entry from a list (creating users) - ansible

Question

First thing first - I'm not an Ansible wiz and I guess there is a better way to do this, but this is how I managed to do this.
I needed to create users on Linux servers, I used this to read the users parameters from a file and create all by using 'with_items'.
This worked perfectly.
I wanted to add an option to create only one user from the list.
This is my yml script:
---
- hosts: all
user: deploy
become: yes
tasks:
- include_vars: ../variables/users.yml
# - command: echo {{ Guser }}
- debug: msg={{ users }}
- name: Create DevOps team users
user: name={{ item.username }} shell=/bin/bash createhome=yes comment='Created by Ansi' groups={{ item.use_sudo }} uid={{ item.use_uid }} group={{ item.use_group }} state=present
ignore_errors: yes
with_items:
- '{{ Guser }}'
when: Guser is defined
And this is how I run it:
ansible-playbook --extra-vars "Guser=gilil2" -l myserver /home/devops/roles/create-users/tasks/create_user_by_name.yml -u deploy
Snip from my variables/users.yml
---
users:
- username: gilil
use_sudo:
use_uid: 2005
use_group: users
- username: gilil2
use_sudo:
use_uid: 1010
use_group: users
- username: gilil3
use_sudo:
use_uid: 1011
use_group: users

Answer 1

Use selectattr Jinja2 filter:
- name: Create DevOps team users
user: name={{ item.username }} shell=/bin/bash createhome=yes comment='Created by Ansi' groups={{ item.use_sudo }} uid={{ item.use_uid }} group={{ item.use_group }} state=present
ignore_errors: yes
with_items: "{{ users | selectattr('username','equalto',Guser|default('uknown')) | list }}"
This will reduce original users list to a list of elements where username attribute equals to Guser vars' value or unknown if Guser is undefined. I assume that there are no user with uknown username, so selectattr can generate empty list in this case.