If you're not already familiar with using jq to manipulate JSON on the command-line, go download it immediately. While it can be a little tricky to learn at first, it'll make your life so much easier.

For example, I recently learned how to filter a JSON result set using a regex to match the value of a particular object property.

Let's say I have a JSON payload that looks like this:

{
	"total": 4,
	"domains": [
		{
			"id": 100,
			"account": 999,
			"name": "alice.com",
			"created": "2021-01-01 00:00:00"
		},
		{
			"id": 101,
			"account": 999,
			"name": "bob.com",
			"created": "2021-01-01 00:00:00"
		},
		{
			"id": 102,
			"account": 999,
			"name": "charlie.com",
			"created": "2021-01-01 00:00:00"
		},
		{
			"id": 103,
			"account": 999,
			"name": "eve.com",
			"created": "2021-01-01 00:00:00"
		}
	]
}

It's super easy to get all of the domain objects using the jq filter .domains[] and it's also trivial to get at only specific fields of each domain object (eg .domains[] | {id,name}).

Now let's say we want to only get the domain object where the name is "charlie.com".

That's where the select() and test() functions come in.

We can use the following filter to accomplish 👆️:

.domains[] | {id,name} | select(.name | test("charlie"))

select takes a boolean expression and, if that expression is true, returns that particular item. Everything else is filtered out.

The test function takes a regex (or simple string to match). In our particular case, test is checking against the name property of each object.

Now let's saw only want the id value of the object that matches our test.

We simply change our filter to the below:

.domains[] | {id,name} | select(.name | test("charlie")) | .id