Which MEL expression correctly reads the path parameter named 'state' from a request to /customers/{state}?

Which MEL expression correctly reads the path parameter named 'state' from a request to /customers/{state}?

• A. #[message.inboundProperties.'http.uri.params'.state]
• B. #[message.inboundProperties.'http.uri.params'.stateParam]
• C. #[message.inboundProperties.'http.uri.params'.STATE]
• D. #[message.inboundProperties.'http.uri.params'.city]

Answer: (A)

Reading a path parameter in MEL comes from the HTTP inbound properties. The HTTP listener exposes path parameters as a map under message.inboundProperties.'http.uri.params', with each parameter name as a key. Since the path is /customers/{state}, the value you want is stored under the key state in that map. The correct MEL expression grabs the map and then the state entry: #[message.inboundProperties.'http.uri.params'.state]. The quotes around http.uri.params are needed because that key contains dots, so it must be treated as a single map key before accessing the state value. Other options don’t fit because they reference a different key or an incorrect case: stateParam wouldn’t match the parameter name, STATE is case-sensitive and would look for a different key, and city would only be correct if the path defined a city parameter.

Reading a path parameter in MEL comes from the HTTP inbound properties. The HTTP listener exposes path parameters as a map under message.inboundProperties.'http.uri.params', with each parameter name as a key. Since the path is /customers/{state}, the value you want is stored under the key state in that map. The correct MEL expression grabs the map and then the state entry: #[message.inboundProperties.'http.uri.params'.state]. The quotes around http.uri.params are needed because that key contains dots, so it must be treated as a single map key before accessing the state value.

Other options don’t fit because they reference a different key or an incorrect case: stateParam wouldn’t match the parameter name, STATE is case-sensitive and would look for a different key, and city would only be correct if the path defined a city parameter.