Getting null values in jq bash

April 24, 2022

I have data.json which looks like this

{
  "type": "AdaptiveCard",
  "body": [
    {
      "type": "TextBlock",
      "text": "Monitoring",
      "wrap": true,
      "weight": "bolder",
      "size": "large"
    },
    {
      "type": "TextBlock",
      "text": "23-04-2022 20:00",
      "wrap": true,
      "size": "Small",
      "isSubtle": true
    },
    {
      "type": "RichTextBlock",
      "inlines": [
      ]
    }
  ],
  "": "http://adaptivecards.io/schemas/adaptive-card.json",
  "version": "1.5"
}

And I’m trying to add values dynamically to the inlines array

sample script

#!/bin/bash

cluster="live"

echo "$(jq --arg c "$cluster" '.body[2].inlines[2] += {"type": "TextRun","text": "Error: Failed Event in Activity Log $c" }' data.json)" > data.json
echo "$(jq '.body[2].inlines[2] += {"type": "TextRun","text": "VMs are in running state" }' data.json)"  > data.json
echo "$(jq '.body[2].inlines[2] += {"type": "TextRun","text": "VMs are  NOT in running state" }' data.json)" > data.json
echo "$(jq '.body[2].inlines[2] += {"type": "TextRun","text": "VMs are OFCOURSE in running state" }' data.json)" > data.json

I have got 2 problems.

first: I have tried finding solution to use dynamic values in the array but it doesn’t expands it.

second: Only the last value is inserted, the previous value somehow becomes null

{
  "type": "AdaptiveCard",
  "body": [
    {
      "type": "TextBlock",
      "text": "OU Monitoring",
      "wrap": true,
      "weight": "bolder",
      "size": "large"
    },
    {
      "type": "TextBlock",
      "text": "23-04-2022 20:00",
      "wrap": true,
      "size": "Small",
      "isSubtle": true
    },
    {
      "type": "RichTextBlock",
      "inlines": [
        null,                                 <== 
        null,                                 <==
        { 
          "type": "TextRun",
          "text": "VMs are OFCOURSE in running state"
        }
      ]
    }
  ],
  "": "http://adaptivecards.io/schemas/adaptive-card.json",
  "version": "1.5"
}

I’m new to jq hence any help with some explanation would help me a lot.
Thanks in advance 🙂

>Solution :

First issue: If you have an empty array, then set a value at index 2 (as with .body[2].inlines[2]), the previous ones (namely index 0 and 1) will be set to null.

Second issue: You always modify the same item (namely .body[2].inlines[2]). += in this case will append the new object to the existing one, but as it’s using the same keys, they will be overwritten.

Solution: Use += on the array, and wrap the new item in brackets (making it another array of one item). This way you can successively populate the existing array.

.body[2].inlines += [{"type": "TextRun","text": "Error: Failed Event in Activity Log $c"}]

Demo

You also may want to put your operations into just one jq call. Either use the pipe | to concatenate the single operations, or, especially in this case, add all items at once as you are adding arrays anyways.

cluster="live"
jq --arg c "$cluster" '
  .body[2].inlines += [{"type": "TextRun","text": "Error: Failed Event in Activity Log $c"}]
  | .body[2].inlines += [{"type": "TextRun","text": "VMs are in running state"}]
  | .body[2].inlines += [{"type": "TextRun","text": "VMs are  NOT in running state"}]
  | .body[2].inlines += [{"type": "TextRun","text": "VMs are OFCOURSE in running state"}]
' data.json

Demo

cluster="live"
jq --arg c "$cluster" '
  .body[2].inlines += [
    {"type": "TextRun","text": "Error: Failed Event in Activity Log $c"},
    {"type": "TextRun","text": "VMs are in running state"},
    {"type": "TextRun","text": "VMs are  NOT in running state"},
    {"type": "TextRun","text": "VMs are OFCOURSE in running state"}
  ]
' data.json

Demo

Output:

{
  "type": "AdaptiveCard",
  "body": [
    {
      "type": "TextBlock",
      "text": "Monitoring",
      "wrap": true,
      "weight": "bolder",
      "size": "large"
    },
    {
      "type": "TextBlock",
      "text": "23-04-2022 20:00",
      "wrap": true,
      "size": "Small",
      "isSubtle": true
    },
    {
      "type": "RichTextBlock",
      "inlines": [
        {
          "type": "TextRun",
          "text": "Error: Failed Event in Activity Log $c"
        },
        {
          "type": "TextRun",
          "text": "VMs are in running state"
        },
        {
          "type": "TextRun",
          "text": "VMs are  NOT in running state"
        },
        {
          "type": "TextRun",
          "text": "VMs are OFCOURSE in running state"
        }
      ]
    }
  ],
  "": "http://adaptivecards.io/schemas/adaptive-card.json",
  "version": "1.5"
}