Ansible: merge dictionaries appending values - data-structures

Question

How can I get a dictionary with values from input separated with a comma? There can be a different number and order of input parameters. What I've tried just gives the error below
- set_fact:
input:
- port: 1234
protocol: TCP
messages: 888-999
file: s3://somepath/file.xsl
- protocol: TLS
port: 5678
path: s3://somepath/mycertificate.crt
messages: 345, 467, 888
file: s3://somepath/file2.xsl
- set_fact:
final_dict:
finalFile: item | map(attribute='file')| join(',')
finalFilter: item | map(attribute='messages')| join(',')
finalPath: item | map(attribute='path')| join(',')
finalProtocol: item | map(attribute='protocol')| join(',')
finalPort: item | map(attribute='port')| join(',')
loop: "{{ input }}"
The error message is as follows:
>"msg": "The task includes an option with an undefined variable. The error was: 'str object' has no attribute 'file'

Answer 1

You do have three issues here:
if you intend to use map, then you need to do it on a list, so, you should have expressions like
var: input | map(attribute='file')
And not act on the item of a loop.
you are missing the {{ ... }} expression delimiters in your final_dict, e.g.:
finalFile: "{{ input | map(attribute='file') | join(',') }}"
and not
finalFile: input | map(attribute='file') | join(',')
Because you do have some undefined keys in your list of dictionaries input, you want to use the default value of map:
finalPath: "{{ input | map(attribute='path', default='') | join(',') }}"
(optionally) if you are going to use input only in that context, make it a variable block. You can define it at the level of the task, play, inventory, ...
Given these three remarks, those two tasks:
- set_fact:
final_dict:
finalFile: "{{ input | map(attribute='file') | join(',') }}"
finalFilter: "{{ input | map(attribute='messages') | join(',') }}"
finalPath: "{{ input | map(attribute='path', default='') | join(',') }}"
finalProtocol: "{{ input | map(attribute='protocol') | join(',') }}"
finalPort: "{{ input | map(attribute='port') | join(',') }}"
vars:
input:
- port: 1234
protocol: TCP
messages: 888-999
file: s3://somepath/file.xsl
- protocol: TLS
port: 5678
path: s3://somepath/mycertificate.crt
messages: 345, 467, 888
file: s3://somepath/file2.xsl
- debug:
var: final_dict
Would yield:
ok: [localhost] =>
final_dict:
finalFile: s3://somepath/file.xsl,s3://somepath/file2.xsl
finalFilter: 888-999,345, 467, 888
finalPath: ',s3://somepath/mycertificate.crt'
finalPort: 1234,5678
finalProtocol: TCP,TLS