Chaining & extraction

Extraction rules capture values from a response; chaining runs the next request with those values. Together they turn “log in, then call the API with the token” into one command.

1. Write and test an extraction rule

A rule has the form VAR=METHOD:EXPR:

Method	Captures	Example
`jsonpath`	A JSONPath value (array indexes supported)	`orderId=jsonpath:$.data.items[0].id`
`jq`	Alias of `jsonpath`	`token=jq:$.token`
`header`	A response header	`location=header:Location`
`regex`	The first capture group	`n=regex:"amount":(\d+)`

Test it against a sample response first. No request is sent:

echo '{"token":"t-123","user":{"id":42}}' | gurl extract 'token=jsonpath:$.token' 'uid=jsonpath:$.user.id'

token = t-123
uid = 42

See gurl extract.

2. Save the rule on the request

gurl save "login" '{{BASE_URL}}/auth/login' -X POST \
  -H 'Content-Type: application/json' \
  -d '{"user":"{{USER}}","password":"{{PASSWORD}}"}' \
  --extract 'token=jsonpath:$.token'

# or add it to an existing request
gurl edit "login" --extract 'token=jsonpath:$.token'

Run it with --json to see what was extracted:

gurl run "login" --env dev --json | jq .extracted

3. Chain to the next request

A post-response script picks the next request with gurl.setNextRequest. Run the first request with --chain:

gurl edit "login" --post-script 'gurl.setNextRequest("profile")'
gurl save "profile" '{{BASE_URL}}/me' -H 'Authorization: Bearer {{token}}'

gurl run "login" --env dev --chain

Extracted and script-set values are runtime values: the highest scope, available to every later request, assertion, script and run-if check in the same run. With --json, each step prints one line (NDJSON).

Skip a step conditionally with a saved run-if expression (VAR == VALUE or VAR != VALUE; missing variables count as empty):

gurl edit "profile" --run-if "token != ''"

4. Keep values for later runs (optional)

Runtime values are dropped at the end of the run, and run prints a note naming them. Add --persist to write them back to their variable origin:

gurl run "login" --env dev --chain --persist

--persist refuses values that contain {{ and locked collections. Details: Variables & placeholders.

Assert on extracted values

gurl run "login" --env dev --assert "extract:token != ''"