EX294 Transform data with filters and plugins Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  {{ packages | map(attribute='name') | zip(packages | map(attribute='version')) | map('join', '-') | list }}

  Why this is correct

  This expression extracts the `name` and `version` attributes from each dictionary, pairs them positionally with `zip`, then joins each pair with a hyphen using `map('join', '-')`. The final `list` materializes the result. It produces exactly the `name-version` strings required in the correct order.

• ✗

  {{ packages | selectattr('name') | map('join', '-') | list }}

  Why it's wrong here

  `selectattr('name')` filters the list to entries that have a truthy `name` attribute, but it does not transform each entry into a string. Applying `join` to dictionaries is invalid because `join` expects a list of strings. This approach neither extracts the fields nor formats them correctly.

• ✗

  {{ packages | map('combine') | list }}

  Why it's wrong here

  `combine` merges dictionaries rather than formatting strings from list elements. Applied through `map` to a list of dictionaries, it would attempt to merge them into one dictionary, not produce `name-version` strings. This does not match the requirement of generating formatted strings for logging.

• ✗

  {{ packages | map('dict2items') | map('join', '-') | list }}

  Why it's wrong here

  `dict2items` converts each dictionary into a list of key/value dictionaries, not a flat pair of strings. Joining those items with a hyphen would not yield `name-version` because each element is itself a dictionary, not a scalar. This expression produces unusable output for the logging requirement.