JSON file update using jq (bash script)

Question

Need some help for change the value in JSON file using jq command.

Error:

[jenkins@devops-dev-02 New]$ jq 'map(if .Tags[11].Key == "Period" then .Tags[11].Value = "Weekly" else . end)' create_snapshot.json
jq: error (at create_snapshot.json:54): Cannot index string with string "Tags"
[jenkins@devops-dev-02 New]$

JSON File:

{
   "DBSnapshotIdentifier":"snapshot-myrds-backup-1",
   "DBInstanceIdentifier":"myrds",
   "Tags":[
      {
         "Key":"Name",
         "Value":"snapshot-myrds-backup-1"
      },
      {
         "Key":"Application",
         "Value":"myapp"
      },
      {
         "Key":"Environment",
         "Value":"Dev and QA"
      },
      {
         "Key":"Period",
         "Value":"Daily"
      }
   ]
}

map() doesn't make sense as the top-level call when your only item is a dict. — Charles Duffy
– Charles Duffy, Commented Aug 29, 2021 at 4:00

peak · Accepted Answer · 2021-08-29 05:45:01Z

2

When you call map() over a dictionary, you operate on only its values, throwing the keys away. The value "snapshot-myrds-backup-1" has no .Tags, nor can you take item 11 of that nonexistent Tags entry.

What you want here is:

.Tags |= map(if .Key == "Period" then .Value = "Weekly" else . end)

map() is usually used to iterate over an array; for JSON objects, map_values() would usually be used to "map" over the object's values while retaining the keys, except for those whose values are mapped to empty.

edited Aug 29, 2021 at 5:45

peak

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answered Aug 29, 2021 at 4:02

Charles Duffy

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