JSONPath#

{{JSONPath "$…"}} extracts a field from the JSON request body. The body is parsed once per request; {{.Body}} still renders the full raw body string.

Syntax#

Path	Meaning
`$`	The whole request body (as JSON string)
`$.user`	Object key `user`
`$.user.name`	Nested object key
`$.items[0]`	Array index 0
`$.items[0].name`	Nested into an array element
`$.items[1].tags[0]`	Deeper nesting

Return Semantics#

Value	Renders as
String	Unquoted (`Ada`)
Number	Unquoted (`42`, `42.5`)
Boolean	`true` / `false`
`null`	`null`
Object / array	Compact JSON (`{"a":1}`)
Missing path, out-of-bounds index, non-JSON body	Empty string (no panic, no fallback)

Example#

id: customer-echo
method: POST
path: /webhooks/customer-echo
response:
  status_code: 200
  template: true
  body: '{"received":{"id":"{{JSONPath "$.customer.id"}}","name":"{{JSONPath "$.customer.name"}}"},"full_payload":{{JSONPath "$"}}}'

Send a request:

curl -X POST http://localhost:8080/webhooks/customer-echo \
  -H "Content-Type: application/json" \
  -d '{"customer":{"id":"cust-42","name":"Ada Lovelace"}}'

Response:

{
  "received": {"id": "cust-42", "name": "Ada Lovelace"},
  "full_payload": {"customer":{"id":"cust-42","name":"Ada Lovelace"}}
}

Note the unquoted {{JSONPath "$"}} at the end — it renders the compact JSON object directly (numbers and booleans render unquoted, so this is safe for valid JSON request bodies).

Restrictions#

JSONPath keys are [A-Za-z0-9_-] only — no spaces, dots, or unicode in keys.

Not supported:

Filters: $.x[?(@.a)]
Wildcards: $.x[*]
Recursive descent: $..x
Negative indices: $.items[-1]

Worked Example#

stubs/template-showcase.yaml is a complete demo combining JSONPath extraction with faker generators:

curl -s -X POST http://localhost:8080/template-showcase \
  -H "Content-Type: application/json" \
  -d '{"customer":{"id":"cust-42","name":"Ada Lovelace"}}'

It echoes your customer.id / customer.name back while generating a realistic event body around them.