Checking if a list is empty...

[Gonzalo Servat]

Hi,

My inventory script returns the correct JSON for a host including an empty list for 'listen_ips', i.e:

{ "listen_ips": [] }

I want to include a task only if the listen_ips list contains at least one element. This doesn't work:

- { include: tasks/repo_server.yml, when: listen_ips > 0 }

Any ideas?

Cheers
GS

[Kahlil Hodgson]

maybe just check if its got the first element:

- { include: tasks/repo_server.yml, when: listen_ips.0 is defined }

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[Gonzalo Servat]

Thanks for the mega-fast response :) That works!

- GS

[Serge van Ginderachter]

On 21 November 2013 07:16, Gonzalo Servat <gse...@gmail.com> wrote:

​​

when: listen_ips > 0

​

​

when: listen_ips|length > 0​

[C. Morgan Hamill]

Serge's response is fine but I believe you can also just do:

> - { include: tasks/repo_server.yml, when: listen_ips }

Python lists have a truthiness of False when empty.
--
Morgan Hamill

[Gonzalo Servat]

Thanks Serge.

- GS

[Gonzalo Servat]

This is the first thing that I tried, but it gave me an error about being unable to evaluate the conditional.

- GS

[Michael DeHaan]

"when: listen_ips|length > 0"

this.

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