Match on the request body

[[rules]]
when.request.method = "POST"
when.request.url_path = "/orders"
[rules.when.request.body.json]
"customer.tier" = { op = "equal", value = "gold" }
[rules.respond]
text = "VIP customer order"

[[rules]]
when.request.method = "POST"
when.request.url_path = "/orders"
[rules.when.request.body.json]
"items.0.sku" = { op = "contains", value = "WIDGET" }
[rules.respond]
text = "widget order"

when.request.body.json keys are dotted paths, not JSONPath — see Body path syntax for the exact resolution rules and why "$.a.b"-style paths don’t work. "customer.tier" walks into a nested object; "items.0.sku" indexes into an array with a numeric segment.

The 25 BodyOperator variants cover far more than string equality — numeric comparison (greater_than, less_than), presence (exists/absent), array checks (array_contains, array_length_at_least), typed equality, and structural matching against a JSON object shape (structural_contains). Full list in the Operator reference.

A worked, verified example layering nested-object, array-index, and numeric-comparison conditions by specificity: crates/apimock/examples/match-headers-and-body/.