How to select ONLY some fields from a YAML file (OpenAPI spec)

[alecthegeek]

yq n00b here.

I want to extract all the "title", "summary", and "description" fields from an Open API spec document.

Like this:

 yq '.. | select(tag == "!!map") | with_entries(select(.key == "summary" or .key == "description" or .key == "title")) |  select(.) '  <(curl -o - https://raw.githubusercontent.com/swagger-api/swagger-petstore/master/src/main/resources/openapi.yaml) 

However the output is scattered with empty results. For example:

{}
{}
description: |-
  This is a sample Pet Store Server based on the OpenAPI 3.0 specification.  You can find out more about
  Swagger at [http://swagger.io](http://swagger.io). In the third iteration of the pet store, we've switched to the design first approach!
  You can now help us improve the API whether it's by making changes to the definition itself or to the code.
  That way, with time, we can improve the API in general, and expose some of the new features in OAS3.

  Some useful links:
  - [The Pet Store repository](https://github.com/swagger-api/swagger-petstore)
  - [The source API definition for the Pet Store](https://github.com/swagger-api/swagger-petstore/blob/master/src/main/resources/openapi.yaml)
title: Swagger Petstore - OpenAPI 3.0
{}
{}
description: Everything about your Pets
description: Find out more
description: Access to Petstore orders
description: Find out more about our store
description: Operations about user
{}
{}

I am sure there must be any easy way to remove the empty entries, but I cannot find it :-(.

Thanks

[mikefarah]

Not really sure how you want to output the results, but you can use pick to pick particular fields.

e.g:

yq '.. | select(has("title") or has("description") or has("summary")) | pick(["title", "summary", "description"])' openapi.yaml

[alecthegeek]

Thank you