Conditional if the variable exists and does not exist

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I have a YAML data like this :

peers:
  eth1:
    hostname: host-01
    state: Idle
  eth2:
    hostname: host-02
    state: Established
  eth3:
    hostname: host-03
    state: Established
ping_to:
  host-02: success
  host-03: success

with jinja2,Ii want to define something like this:

{% for key, value in peers.iteritems() %}
{% for key2, value2 in ping.iteritems() %}
{% if value.hostname is exist in key2 %}
ping is success
{% elif value.hostname is not exist key2 %}
ping not found
{% endif %}
{% endfor %}
{% endfor %}

So basically if the hostname value is in one of the ping keys, then it is a success. If not, then fail. how to say it if the hostname exists or does not exist?

conditional-statements if-statement jinja2
1 Answers

You actually do not need that nested loop, you could simply assert that the hostname value is a key in the ping_to dictionnary:

{% for interface_name, interface_value in peers.items() %}
  {%- if ping_to[interface_value.hostname] is defined -%}
    ping is success
  {%- else -%}
    ping is not found
  {%- endif %}
{% endfor %}

Another, simpler way, would be to use the default filter, to have an alternative output when the key is indeed not defined.

{% for interface_name, interface_value in peers.items() -%}
  ping is {{ ping_to[interface_value.hostname] | default('not found') }}
{% endfor %}

Both those snippets would give:

ping is success
ping is success
ping is not found
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