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Json – Using if-then-else-end in jq to handle missing values

This is the command I use to pull the info I need:

.results | .[] | {id, name: .general.name, platform: .general.platform, site: .general.site.name, ea_site: .extensionAttributes.[] | select(.definitionId=="57").values.[]}

When .extensionAttributes.[] | select(.definitionId=="57").values.[] is empty, jq does not display any associated items at all.

What I’d like to do is check if .extensionAttributes.[] | select(.definitionId=="57").values.[] < 0 and return empty otherwise return the content. I’m trying to use if-then-else-end, but can’t seem to get the syntax correct.

You can find sample data in jqplay here.
Line 1218 in the json input has the empty value.

Desired output:

{ "id": "3882", "name": "Kresge-iMac-900", "platform": "Mac", "site": "Arts", "ea_site": "Arts"}
{ "id": "3881", "name": "c-loaner", "platform": "Mac", "site": ".Production", "ea_site": "blank"}
Tags:

3

Answers


  1. 0

    If you fix the test and add parentheses, the code in your comment may do what you intend:

    .results | .[] | {
    id,
    name: .general.name,
    platform: .general.platform,
    site: .general.site.name,
    ea_site: (
        .extensionAttributes.[] | select(.definitionId=="57").values |
        if ( . | length > 0 ) then .[] else "blank" end
    )
}

    Note that if the values array contains multiple elements, you’ll get a copy of the object you are creating for each one.

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  2. 0

    You can use the more concise // operator:

    jq '.results[] | {
    id, name: .general.name, platform: .general.platform, site: .general.site.name,
    ea_site: ((.extensionAttributes.[] | select(.definitionId=="57").values.[]) // null)
  }' data.json

    # output
{
  "id": "3882",
  "name": "Kresge-iMac-900",
  "platform": "Mac",
  "site": "Arts",
  "ea_site": "Arts"
}
{
  "id": "3881",
  "name": "c-loaner",
  "platform": "Mac",
  "site": ".Production",
  "ea_site": null
}
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  3. 0

    A simple way to use if...then...else...end here based on your own attempt is as follows:

    .results
| .[]
| {id, name: .general.name, platform: .general.platform, site: .general.site.name,
   ea_site:
       ((.extensionAttributes[] | select(.definitionId=="57").values) 
         | if . == [] then . else .[] end)
       }

    Please note that in jq terminology, the "empty list" is quite different from empty: the latter is both a keyword and a reference to the empty stream. (For me, it was your reference to line 1218, in which the value is [], that clarified the intent of the question.)

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