Conditionally output a field?

In this example I only want isGreaterThanOne field to be shown if it’s true. Here’s what I started with (always shown)

echo '[{"a":5},{"a":1}]' | jq '[.[] | {value:.a, isGreaterThanOne:(.a>1)}]'

I inserted an if statement

echo '[{"a":5},{"a":1}]' | jq '[.[] | {value:.a, X:(if .a>1 then "Y" else "N" end) }]'

Then got stuck trying to move the field into the conditional. Also it seems like I must have an else with an if

echo '[{"a":5},{"a":1}]' | jq '[.[] | {value:.a, (if .a>1 then (K:"Y)" else (L:"N") end) }]'

I want the below as the result (doesn’t need to be pretty printed)

[
{
    "value": 5,
    "X": "Y"
},
{
    "value": 1,
}
]

>Solution :

You can add an empty object in case of failure:

map({value: .a} + if .a > 1 then {X: "Y"} else {} end)

[
  {
    "value": 5,
    "X": "Y"
  },
  {
    "value": 1
  }
]

Demo