How do I extract this field using JQ?-CodePudding

JQ makes me irrationally angry and I despise its very existence. I have been trying to extract the value of the tf-name key for 30 minutes and I'm going to become a hermit if I have to make another attempt at this. Please, how do I get tmp as a a result?

➜  aws resourcegroupstaggingapi get-resources --tag-filters Key=tf-name,Values=tmp --profile=test | jq   
                               
{
  "ResourceTagMappingList": [
    {
      "ResourceARN": "arn:aws:s3:::stack-hate-1234567890salt",
      "Tags": [
        {
          "Key": "aws:cloudformation:stack-name",
          "Value": "hatestack"
        },
        {
          "Key": "aws:cloudformation:stack-id",
          "Value": "arn:aws:cloudformation:us-west-2:6666666666666:stack/FSStack/hate-hate-hate-123456789"
        },
        {
          "Key": "tf-name",
          "Value": "tmp"
        },
        {
          "Key": "aws:cloudformation:logical-id",
          "Value": "hatebucket1234"
        },
        {
          "Key": "aws-cdk:auto-delete-objects",
          "Value": "true"
        }
      ]
    }
  ]

CodePudding user response：

Its quite simple to extract, once you know the type of the top level objects. You can see ResourceTagMappingList is a list of records, so it should have a [] notation following it, which I think most beginners with jq tend to miss out. So

.ResourceTagMappingList[].Tags | from_entries."tf-name"

should get you the desired value. See jqplay demo

The way it works is, the from_entries function takes an array of objects with key names key and value and transforms it to a value only pair. From there, we extract only the key name tf-name. The special double quotes are needed because the key name here contains a meta-character -, which should be quoted to treat the whole string as the key name.

Another way would be to use a select statement like below

.ResourceTagMappingList[].Tags[] | select(.Key  == "tf-name").Value