Front-Matter files with content and CONDITIONAL APPROACH

[ad-borges]

I have Front Matter files like this:

---
title: BMW i320 M3 150HP Petrol 2020
category: sportscar
color: metal
---

MD content Starts Here
Lorem ipsum Lorem Ipsum Lorem Ipsun
Lorem ipsum Lorem Ipsum Lorem Ipsun

Using kislyuk's python-yq, I managed to accomplish my goal using following command:

yq -i -y '
    if (.category=="sportscar") and (.title | contains(" Petrol")) then
        .engine = "fuel"
      elif (.category=="sportscar") and (.title | contains(" Gasoline")) then
        .engine = "fuel"
      elif (.category=="sportscar") and (.title | contains(" Diesel")) then
        .engine = "fuel"
      elif (.category=="sportscar") and (.title | contains(" Ethanol")) then
        .engine = "fuel" 
      elif (.category=="sportscar") and (.title | contains(" Aviation Gas")) then
        .engine = "fuel"
      else
        .engine = "electric"
      end' *

THIS WORKS ONLY IF MD FILE HAVE NO CONTENT BELLOW ---
And I cant lose this content.

So I went to mikefarah's yq version. Because of that --front-matter=process option.

yq -i --front-matter=process '
    if (.category=="sportscar") and (.title | contains(" Petrol")) then
        .engine = "fuel"
      elif (.category=="sportscar") and (.title | contains(" Gasoline")) then
        .engine = "fuel"
      elif (.category=="sportscar") and (.title | contains(" Diesel")) then
        .engine = "fuel"
      elif (.category=="sportscar") and (.title | contains(" Ethanol")) then
        .engine = "fuel" 
      elif (.category=="sportscar") and (.title | contains(" Aviation Gas")) then
        .engine = "fuel"
      else
        .engine = "electric"
      end' *

Actually this can process the md files, without mess with the content part
But this yq version dont work with If Elif Else approach.

So it throws me this error:

Error: parsing expression: Lexer error: could not match text starting at 1:6 failing at 1:8.
	unmatched text: "if"

How can i make this conditional approach, without lose the content part of MD Files?
I have more than 2000 files to manage.... +80% has content bellow ---
Im working on MacOsx Terminal

I need this final scenario:

---
title: BMW i320 M3 150HP Petrol 2020
category: sportscar
color: metal
engine: fuel
---

MD content Starts Here
Lorem ipsum Lorem Ipsum Lorem Ipsun
Lorem ipsum Lorem Ipsum Lorem Ipsun

[mikefarah]

yq doesn't (yet) have if/elif - however you can get the same result using select:

 yq '
  ( select(.category == "sportscar" and (.title | contains(" Petrol"))) | .engine ) = "petrol"  | 
  ( select(.category == "sportscar" and (.title | contains(" Gasoline"))) | .engine ) = "petrol" |
  ( select(.engine == null) | .engine ) = "electric"
' file.yaml

Note that you may be able to simplify your logic using RegEx:

yq '
  ( select(.category == "sportscar" and (.title | test("(?i)\b(petrol|gasoline)\b"))) | .engine ) = "petrol"  | 
  ( select(.engine == null) | .engine ) = "electric"
' file.yaml

This regex ignore case (?i) and looks for word boundries on both sides \b.