What is the difference between PUT and POST?

Question

Some teach that POST is to send data to create something and that PUT is to update, but found poorly explained.

So, after all, what is the difference between the PUT method and the POST?

When I must wear one and the other?

Answer 1

Technically none. Only semantics change. Read the RFC:

The fundamental difference between POST and PUT requests is reflected in the difference in meaning of the Request-URI. The URI on a POST request identifies the resource that will manipulate the appended entity. The resource may be a data acceptance process, a gateway for another protocol, or a separate entity that accepts annotations. In contrast, the URI in the PUT request identifies the appended entity with the request -- the user agent knows which URI is intended and the server MUST NOT attempt to apply the request to another resource. If the server wants the request to be applied to a different URI, it MUST send a 301 (Moved Permanently) response; user agent You can then make your own decision on whether or not to redirect the request.

In other words, PUT should be used in more specific situations where you want to send information and do nothing but store it in some way. The POST is more general, it assumes that information is only part of the process that will be carried out. The POST allows to have any side effects, or at least it is expected that this can occur. PUT is expected not to have something unknown, or undesirable. It is idempotent (homage to the bfavaretto).

In some scenarios it is possible to think of more specific semantics (REST, I’m talking about you) for each verb. But essentially they work similarly. In CRUD scenarios, the PUT normally is used to update something and the POST to create (or do other operations that does not fit into the basic CRUD), just as GET is used to read, and DELETE obviously to delete.

Of course, the recommendation is to follow what the RFC says, but it’s almost safe to say it doesn’t matter much. In the future it could be that they impose some restriction or have some effect based on what the RFC says. And then anything that didn’t follow her would have problems. " Legally" they could do this, but since no one follows the RFC, it would break so much, that it will never be changed.

When in doubt, everyone uses the POST that is better known and should always work. I have my doubts if it should not be the other way around. But the damage is already done.

Although it does not answer directly, I strongly advise to read the response indicated by bfavaretto. Has another useful also.

Answer 2

The post is a verb HTTP for data submission within the package on any type of request, very similar to get, changing only the location and size available for data storage. Against put is a verb that carries the meaning of creating elements, such as sending a file or entity.

Update 1

When requesting a resource, such as a query, it is usual to use the information passage using get.

URI: http://servidor/recurso/consulta/{id}
GET: {id}

However, use the verb get generates URI's individual values for each given value, exposing the information and preventing cache optimization if the request response is the same. In this way we have the verb post to load the information inside the package without being in the URI.

URI: http://servidor/recurso/consulta
POST: {id}

The verbs put and delete are loaded with semantics. When creating or transferring a resource the most appropriate verb is put. To exclude a resource the most appropriate verb is the delete.

URI: http://servidor/recurso/novo
PUT: {nome,cidade,estado}

URI: http://servidor/recurso/excluir/{id}
DELETE

Answer 3

PUT places a file or resource in a URI specific. If a file or resource already exists in this URI, the method PUT will replace the file (or resource). If there is no file or resource there, the method PUT creates a.

POST sends data to a URI specific to handle the request. The server web, at this point can determine what to do with the data in the context of the specified resource.

source (English)

Answer 4

PUT is an idempotent operation to "place" (CREATE OR REPLACE) a resource at a given URL, in other words, it is used when the URL uniquely identifies the resource to be created or updated, and if the operation is successful there will be after a feature in that URL exactly as you sent, regardless of what was before.

For other cases, use POST.

For example, let’s assume an api that allows you to create or update users: POST /user returns a new user with the metadata sent in the request body. Normally the ID is created on the server and returned in the response. PUT /user/12345 creates or replaces user 12345 with the information sent in the body of the request

Note that in the first case if we repeat the same request theoretically we will be creating another user with the same data (but with different ids), or the second request will return some error, in the second case we will be replacing the user 12345 by another exactly the same if the data in the body of the request are the same.

Note: PUT is used when sending a complete object. If you want to update only a part of it and not resend everything, use PATCH.