POST method
POST asks the target resource to process enclosed content according to that resource's semantics.
- methods
- request content
Defined meaning
POST asks the target resource to process the enclosed representation according
to the resource’s own semantics. Common uses include submitting data, creating a
resource through a collection, appending data, and triggering an operation.
POST /messages HTTP/1.1
Host: example.invalid
Content-Type: text/plain
Content-Length: 5
hello
Expected result: /messages defines how hello is processed. Creation can be
reported with 201 Created and Location; another valid application can return a
different status matching its result.
Properties
POST is not safe and is not idempotent by definition. Application-level idempotency keys can make repeated operations safe under a documented private contract, but they do not change the registered method property.
POST responses are cacheable only when they carry explicit freshness information and meet other caching requirements. Many caches do not implement POST reuse.
Common mistake
Do not use a redirect code with historical method rewriting when the follow-up must preserve POST and its content. Choose the redirect semantics deliberately.