I guessed that the name of each of the request method has a relationship with the operations they performed in some manner. But I can't get it!
Detials:
GET means posted argument are showed in the url and POST means they are sent but not shown in the url. But what is that related to POST/GET? What is gotten/posted or what does the posting/getting job? Do you have any glues?
I understand what GET and POST method is. What I wanna know is why do we GET/POST, why don't we call it TYPE1/TYPE2, or another more make-sense name like ON-URL/OFF-URL
Please discuss if you know that.
This should help you:
Methods GET and POST in HTML forms - what's the difference?
http://www.cs.tut.fi/~jkorpela/forms/methods.html
The Definitive Guide to GET vs POST
http://carsonified.com/blog/dev/the-definitive-guide-to-get-vs-post/
get and post
http://catcode.com/formguide/getpost.html
From RFC 2616:
GET
The GET method means retrieve whatever information (in the form of an entity) is identified by the Request-URI.
POST
The POST method is used to request that the origin server accept the entity enclosed in the request as a new subordinate of the resource identified by the Request-URI in the Request-Line.
So, GET should be used to read a resource, whereas POST should be used to create, update, or delete a resource.
GET and POST are called HTTP Verbs. See the RFC for details.
GET will get a resource identified by a URL. If using GET as the action for a form the entries will be encoded in the URL (look at a google search for an example).
POST will send the data separately, to the specified URL.
The biggest difference is that if you use GET on a form submit, you can copy the URL of the page you landed at and use it directly to get the same results. All information will also be visible in the URL (don't use this method for passwords). If you POST the data the URL of the landing page will not be enough to reproduce the same results; you will have to go through the form again.
Take a look at the RFC definitions here:
http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html
But essentially, GET is used to retrieve a resource and POST is used to create a new one or make a change to a resource.
Seems to me that #Nam G. VU is asking an English-language question.
"Get" implies that the flow of data is from the server to the client. More specifically, the client is asking the server to send some data.
"Post" implies that the client is pushing data to the server. The word "post" implies that it's a one-way operation.
Of course, neither of these is 100% unidirectional: GETs can send data to the server in the
URL as path and/or query arguments, and POSTS return data to the client.
But, in the simplest sense, the English verbs imply the principal direction of data flow.
From the REST standpoint, GET METHOD signifies that it is used to GET a (list of similar) resource(s). POST is used to create (or POST) a resource.
Apart from this, GET carries all parameters in the URL in the format of ?name=value& pairs, whereas POST carries all of them in the Request Body.
Related
Chapter 9.5 POST of the HTTP/1.1 spec includes the sentence:
If a resource has been created on the origin server, the response
SHOULD be 201 (Created) and contain an entity which describes the
status of the request and refers to the new resource, and a Location
header
It is referenced frequently. The itention is clear, but I have issues with the meaning of some of the chosen words.
What does "contain an entity which describes the status of the request and refers to the new resource" exactly mean?
How shall the entity (entity-header fields and entity-body) describe the status of the request? Isn't the status of the request 201 (Created)? Whow shall this status be described? Does "describe the status of the request" mean the result, in other words the current entity status?
Thinking of a Web API with JSON representation does it mean that the entity should be included in a JSON representation after a successful POST that created an entity? Thinking of a created image, should the image data be returned in the response body?
What is meant with refers to the new resource? The uri is already in the location header. Shall it be repeated in the body or does it mean just to add an id?
Is there a good source with examples of different entities and its responses to a creation POST?
I think it varies based on the resource you're creating, suppose your posting to a /profile/ resource maybe a payload containing multiple profile fields to update - your return would indicate it was successful and include a reference to the fields you posted (it can even return the entire profile attributes with fields you've updated including all fields);
Another example in the image sense, suppose you are posting a Base64 encoded image to a service that stores the image, the response should show the status (ie: accepted, rejected, file too larage, MIME type accurate or not, etc.) - and within the returned payload if successful you'd want the response to not be vague but return the path and/or filename of the image uploaded;
The header returns the response code - the body returns information related to the invoked action's entity response (it can be a set of fields, a URL, a useful response that when parsed back it can be actionable or informative);
These are principles of good coding, but also keep note of security and not to expose anything in a return that could potentially be damaging for example; when creating a service you want to be clear and provide concise and useful returns so when the client consumes the API it knows what to do, what to expect, etc.
I need to reuse value which is generated for my previous request.
For example, at first request, I make a POST to the URL /api/products/{UUID} and get HTTP response with code 201 (Created) with an empty body.
And at second request I want to get that product by request GET /api/products/{UUID}, where UUID should be from the first request.
So, the question is how to store that UUID between requests and reuse it?
You can use the Request Sent Dynamic values https://paw.cloud/extensions?extension_type=dynamic_value&q=request+send these will get the value used last time you sent a requst for a given request.
In your case you will want to combine the URLSentValue with the RegExMatch (https://paw.cloud/extensions/RegExMatch) to first get the url as it was last sent for a request and then extract the UUID from the url.
e.g
REQUEST A)
REQUEST B)
The problem is in your first requests answer. Just dont return "[...] an empty body."
If you are talking about a REST design, you will return the UUID in the first request and the client will use it in his second call: GET /api/products/{UUID}
The basic idea behind REST is, that the server doesn't store any informations about previous requests and is "stateless".
I would also adjust your first query. In general the server should generate the UUID and return it (maybe you have reasons to break that, then please excuse me). Your server has (at least sometimes) a better random generator and you can avoid conflicts. So you would usually design it like this:
CLIENT: POST /api/products/ -> Server returns: 201 {product_id: UUID(1234...)}
Client: GET /api/products/{UUID} -> Server returns: 200 {product_detail1: ..., product_detail2: ...}
If your client "loses" the informations and you want him to be later able to get his products, you would usually implement an API endpoint like this:
Client: GET /api/products/ -> Server returns: 200 [{id:UUID(1234...), title:...}, {id:UUID(5678...),, title:...}]
Given something like this, presuming the {UUID} is your replacement "variable":
It is probably so simple it escaped you. All you need to do is create a text file, say UUID.txt:
(with sample data say "12345678U910" as text in the file)
Then all you need to do is replace the {UUID} in the URL with a dynamic token for a file. Delete the {UUID} portion, then right click in the URL line where it was and select
Add Dynamic Value -> File -> File Content :
You will get a drag-n-drop reception widget:
Either press the "Choose File..." or drop the file into the receiver widget:
Don't worry that the dynamic variable token (blue thing in URL) doesn't change yet... Then click elsewhere to let the drop receiver go away and you will have exactly what you want, a variable you can use across URLs or anywhere else for that matter (header fields, form fields, body, etc):
Paw is a great tool that goes asymptotic to awesome when you explore the dynamic value capability. The most powerful yet I have found is the regular expression parsing that can parse raw reply HTML and capture anything you want for the next request... For example, if you UUID came from some user input and was ingested into the server, then returned in a html reply, you could capture that from the reply HTML and re-inject it to the URL, or any field or even add it to the cookies using the Dynamic Value capabilities of Paw.
#chickahoona's answer touches on the more normal way of doing it, with the first request posting to an endpoint without a UUID and the server returning it. With that in place then you can use the RegExpMatch extension to extract the value from the servers's response and use it in subsequent requests.
Alternately, if you must generate the UUID on the client side, then again the RegExpMatch extension can help, simply choose the create request's url for the source and provide a regexp that will strip the UUID off the end of it, such as /([^/]+)$.
A third option I'll throw out to you, put the UUID in an environment variable and just have all of your requests reference it from there.
I'm writting a RESTful api, and at I'm thinking about the process of a user creating a key. I have the following possibilities:
GET request to /new/<keyname> - although it's very easy I think I won't use this, because I heard GET is for retrieving and/or listing information;
POST request to /<keyname> - This seemed to me easy and simple enough, but does not pass any data in the request body. Can I do it this way ? Is this weird ?
POST request to /keys passing in the request body "keyname=SomeKey" - Is this the correct way ?
I looked at this API from joyent and in all their PUT and POST requests they pass some data in the request body. Is this expected ? Is it really wrong not to require a request body in a PUT and POST request ?
I asked this question on the Http-WG. This was the most precise answer I got http://lists.w3.org/Archives/Public/ietf-http-wg/2010JulSep/0276.html
In summary, POST does not require a body. I would expect the same justification can be applied to PUT.
RFC2616 is the base RFC for HTTP 1.1
In the most general form, an HTTP message is this (note the optional body):
generic-message = start-line
*(message-header CRLF)
CRLF
[ message-body ]
start-line = Request-Line | Status-Line
Reading further gives this:
9.5 POST
The POST method is used to request that the origin server accept the
entity enclosed in the request as a new subordinate of the resource
identified by the Request-URI in the Request-Line. ...
and
9.6 PUT
The PUT method requests that the enclosed entity be stored under the
supplied Request-URI. ...
The fundamental difference between the POST and PUT requests is
reflected in the different meaning of the Request-URI. The URI in a
POST request identifies the resource that will handle the enclosed
entity. That resource might be a data-accepting process, a gateway to
some other protocol, or a separate entity that accepts annotations.
In contrast, the URI in a PUT request identifies the entity enclosed
with the request -- the user agent knows what URI is intended and the
server MUST NOT attempt to apply the request to some other resource.
Both POST and PUT include the phrase entity enclosed in the request.
Based on my reading, I believe that a body is desired (a non-normative description, I know) for both POST and PUT.
In the context of REST, POST is create and PUT is update. I can imagine creating an empty object (perhaps a placeholder for future information), but I don't imagine much use of an empty update.
It is not required. You can send a POST/PUT request without a body and instead use query string parameters. But be careful if your parameters contain characters that are not HTTP valid you will have to encode them.
For example if you need to POST 'hello world' to and end point you would have to make it look like this: http://api.com?param=hello%20world
Probably the best way is your third option: POST to /keys with keyname=SomeKey.
Here's why: You may wish to add another function to your API, for example create_new_user. It would then be difficult to tell the difference between a user trying to POST a key called create_new_user and a user trying to use the create_new_user function.
You are correct in saying that you should not be using GET to do this operation as the GET operation "SHOULD NOT have the significance of taking an action
other than retrieval." (RFC 2616).
To answer your question in one line. Yes it is expected to have Body/Content in body, but it is not required(Mandatory).
According to okHttp3 (an HTTP library for android): the following methods need a body: POST, PUT, PATCH, PROPPATCH (WebDAV) and REPORT (source). It even crashes if you try to do a request with the given methods without a body.
I'm working on a REST server. I have an order RESOURCE.
From my understanding the PUT verb should create a new order based on the URL. My question is: How can this work if the resource is new and you don't know the ID of the new order?
I know the debate about POST vs PUT, but I'm quoting the w3 specs for PUT http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html
"If the Request-URI does not point to an existing resource, and that URI is capable of being defined as a new resource by the requesting user agent, the origin server can create the resource with that URI"
In RESTful APIs, PUT is typically used to update a resource or create one if it doesn't exist at the specified URL (i.e. the client provides the id). If the server generates the id, RESTful APIs typically use a POST to create new resources. In the latter scenario, the generated id/url is usually returned or specified in a redirect.
Example: POST /orders/
According to W3C Both PUT and POST can be used for update and/or create.
The basic difference between them is how the server handles the Request-URI. PUT URI identifies the entity and the server should't try to map it to another URL, while POST URI can be a handler for that content. Examples:
It's OK to POST a new order to /order, but not a PUT. You can update order 1 with a PUT or POST to /order/1.
To put it simply POST is for creating and PUT is for updating. If you don't have an ID for an object because it isn't created yet, you should be using a POST. If an object DOES exist and you just don't have the ID for it, you're going to have to search for it using a GET of some kind.
The thing to remember is Idempotence. A PUT (and GET for that matter) is idempotent. Basically meaning, you can hit the same URL over and over and it shouldn't make a difference the 2nd or 3rd time (It edits the data once, and calling it again it doesn't make that change again). However a POST is not idempotent. Meaning, you hit the same URL 3 or 4 times in a row and it's going to keep changing data (creating more and more objects). This is why a browser will warn you if you click back to a POST url.
You say, "don't know the ID of the new order" therefore the following is not true "URI is capable of being defined as a new resource by the requesting user agent", therefore PUT is not appropriate in your scenario.
Where is the confusion? I am of course assuming the Id would be part of the URL.
I would like to POST an entity as follows
POST /example.org/MyEntity/100
Based on the passed entity, the server would like to draw the users attention to a particular part of the response using a fragment identifier. e.g.
/example.org/MyEntity/100#InterestingPart
How do I return this new URL to the client. I am assuming I could do some form of redirect using a 3XX response code, but I actually do not want the client to do another request because the only difference between the two URLs is the fragment. At the moment it seems that a 307 return code would be the most appropriate because according to the spec you should not automatically redirect a POST.
Is there are better way?
Update: My client is not limited to the constraints of a web browser. I am just looking at this from the perspective of HTTP.
Update2: Based on my reading of RFC2616, I can see nothing stopping me from returning a 200 and a Location header that contains the fragment identifier. Anyone know of a reason why I cannot do that?
I think the only sensible solution is to have action URL have static fragment identifier, like <form method="post" action="/action#anchored"> and then put an anchor wherever you want user to look at while generating page.
But, to answer the Update2: no, there's no reason to avoid it.
My inclination is to return 201 - and have the location header point to the URI you want the client to GET.
I didn't look, but IIRC nothing dictates that the location header points to the resource created, so it should be spec legal.
You should normally redirect every POST to avoid problems with refreshing the page and the use of the back button. This is known as the PRG (POST Redirect Get) pattern:
http://blog.httpwatch.com/2007/10/03/60-of-web-users-can%E2%80%99t-be-wrong-%E2%80%93-don%E2%80%99t-break-the-back-button/
Although, this does incur the cost of another round trip to the server it makes your web application much more user friendly.
You could then add the fragment onto the redirected URL.
There's an example of PRG with a fragment on this page:
http://www.httpwatch.com/httpgallery/redirection/
POSTing to the URI:
http://example.org/MyEntity/100
implies to me that a MyEntity resource called "100" already exists. If that's the case, why not use PUT instead? Is this an update or a create operation?
An alternative might be:
POST http://example.org/MyEntities
Now your service has a choice to make from at least two possibilities:
Return 201 Created. Set the Location header to be the URI you want the client to use (e.g.: http://example.org/MyEntities/100#InterestingPart). Add the representation of the new resource to the body.
Return 204 No Content. Same as above, but no body. This option requires a subsequent GET to fetch the representation, which sounds like what you're trying to avoid.
Neither approach requires redirection and both can return as specific a URI as you desire.
I am curious though, why is the #InterestingPart significant? Why not just return the entire representation and its URI http://example.org/MyEntities/100 in the Location header - and let clients decide for themselves what's interesting or not? If the answers have something to do with only a small part of the resource being of interest (or being modified) during a request, how feasible would it be to break MyResource into a main resource and one or more subordinate resources? For example:
/MyResources/100/CoolThings
/MyResources/100/CoolThings/42
/MyResources/100/InterestingThings
/MyResources/100/InterestingThings/109