I'm working on an API that accepts data from remote clients, some of which where the key in an HTTP POST almost functions as an array. In english what this means is say I have a resource on my server called "class". A class in this sense, is the type a student sits in and a teacher educates in. When the user submits an HTTP POST to create a new class for their application, a lot of the key value pairs look like:
student_name: Bob Smith
student_name: Jane Smith
student_name: Chris Smith
What's the best way to handle this on both the client side (let's say the client is cURL or ActiveResource, whatever..) and what's a decent way of handling this on the server-side if my server is a Ruby on Rails app? Need a way to allow for multiple keys with the same name and without any namespace clashing or loss of data.
My requirement has to be that the POST data is urlencoded key/value pairs.
There are two ways to handle this, and it's going to depend on your client-side architecture how you go about doing it, as the HTTP standards do not make the situation cut and dry.
Traditionally, HTTP requests would simply use the same key for repeated values, and leave it up to the client architecture to realize what was going on. For instance, you could have a post request with the following values:
student_name=Bob+Smith&student_name=Jane+Smith&student_name=Chris+Smith
When the receiving architecture got that string, it would have to realize that there were multiple keys of student_name and act accordingly. It's usually implemented so that if you have a single key, a scalar value is created, and if you have multiples of the same key, the values are put into an array.
Modern client-side architectures such as PHP and Rails use a different syntax however. Any key you want to be read in as an array gets square brackets appended, like this:
student_name[]=Bob+Smith&student_name[]=Jane+Smith&student_name[]=Chris+Smith
The receiving architecture will create an array structure named "student_name" without the brackets. The square bracket syntax solves the problem of not being able to send an array with only a single value, which could not be handled with the "traditional" method.
Because you're using Rails, the square bracket syntax would be the way to go. If you think you might switch server-side architectures or want to distribute your code, you could look into more agnostic methods, such as JSON-encoding the string being sent, which adds overhead, but might be useful if it's a situation you expect to have to handle.
There's a great post on all this in the context of JQuery Ajax parameters here.
Send your data as XML or JSON and parse whatever you need out of it.
Related
Because I am rewriting a legacy app, I cannot change what the clients either send or accept. I have to accept and return JSON, HTML, and an in-house XML-like serialization.
They do, fortunately set headers that describe what they are sending and what they accept.
So right now, what I do is have a decoder module and an encoder module with methods that are basically if/elif/else chains. When a route is ready to process/return something, I call the decoder/encoder module with the python object and the header field, which returns the formatted object as a string and the route processes the result or returns Response().
I am wondering if there is a more Quart native way of doing this.
I'm also trying to figure out how to make this work with Quart-Schema. I see from the docs that one can do app.json_encoder = <class> and I suppose I could sub in a different processor there, but it seems application global, there's no way to set it based on what the client sends. Optimally, it would be great if I could just pass the results of a dynamically chosen parser to Quart-Schema and let it do it's thing on python objects.
Thoughts and suggestions welcome. Thanks!
You can write your own decorator like the quart-schema #validation_headers(). Inside the decorator, check the header for the Content-Type, parse it, and pass the parsed object to the func(...).
I have developed a ASP.NET MVC application. I have a conroller with the name EmployeeController and it got a method called GetEmployeeByName. GetEmployeeByName() takes a name of type string as parameter.
So When I send a request like this, i get the data back :
someDomain:9999/Employee/GetEmployeeByName/Roger Federer
But if the name contains an '&' (you & me), I get a '400 Bad Request' as response from server.
someDomain:9999/Employee/GetEmployeeByName/you%20&%20me
Even if i encode it dont get a reposne back
someDomain:9999/Employee/GetEmployeeByName/you%20&%20me
What is the right way to encode such (data with special character) data?
What is the right way to encode such (data with special character) data?
The right way is to use a query string parameter and not be putting those things as part of the uri portion. Read the following blog post from Scott Hansleman. I will only quote hos conclusion:
After ALL this effort to get crazy stuff in the Request Path, it's
worth mentioning that simply keeping the values as a part of the Query
String (remember WAY back at the beginning of this post?) is easier,
cleaner, more flexible, and more secure.
As you can see in the blog post there are some hacky ways to make it work and circumvent IIS handling but it simply is not something that I would recommend you venturing into. Just put this name in the query string.
Suppose you are working on an API, and you want nice URLs. For example, you want to provide the ability to query articles based on author, perhaps with sorting.
Standard:
GET http://example.com/articles.php?author=5&sort=desc
I imagine a RESTful way of doing this might be:
GET http://example.com/articles/all/author/5/sort/desc
Am I correct? Or have I got this REST thing all wrong?
I'm afraid your question really misses the point of REST. From a purely theoretical perspective there is absolutely no advantage or disadvantage to either of those urls from a REST perspective. In practice, those urls may behave differently with different caches, and certainly server frameworks are going to parse them differently. Despite what you hear from the framework developers, there is no such thing as a RESTful URL.
From the perspective of REST those two URLs are simply identifiers that can be dereferenced. If you want to start building REST apis that will benefit from the characteristics described in the dissertation, you need to start thinking in terms of content that is returned when you dereference the URL and how that content is linked together using URLs embedded in the content.
I realize this does not help you much in trying to resolve what you consider to be your problem. What I can tell you is that one of the major intents of REST is to allow your URLs to be completely under the control of the server and can change without impacting your client applications. Therefore, my recommendation is to pick whatever url structure works most easily with the framework you are using to serve the resource representations. Certainly do not look to the REST dissertation to tell you what is the right and wrong way of formatting your URLs and anyone who tells you that your URLs are not RESTful is confused. Probably what they are telling you is the server framework, they are used to using for creating RESTful interfaces, requires URLs to be structured this way.
It's not what your URI looks like that matters, it is what you do with it that matters.
Using a query string is not more or less RESTful than using path components. The URI Generic Syntax (RFC 3986, January 2005) defines that they're just as important in identifying the resource. So yes, as others point out, it's not important to REST. (Note that in the obsoleted-by-RFC-3986 RFC 2396, the query string was not defined to be identifying the resource, but rather a string of information to be interpreted by the resource.)
However, URI design is important, because as an owner of a URI namespace (i.e. the holder of the domain name where the URIs will live) you want the URIs to be long lived. As wise men have stated earlier: Cool URIs don't change!
The choice of using query strings vs path components depends on how your resources are identified, and how they will be identified in years to come. If there's a hierarchy that stands out, then it might be that this should be reflected in the URI, at least if that hierarchy is relatively permanent, and that things don't move around all the time.
It's also important to note that the actual URIs are only meaningful to two parties:
Servers, who need to forge and parse URIs
Human beings who might see a URI in passing might learn things from the URI.
By contrast, client applications are usually not allowed to do URI introspection. So your choice of query strings vs path components boils down to what you think you can live with ten (or 100) years from now.
You are mostly right. The thing with REST api's is to focus on the nouns.
What does the noun all do in this case? Wouldn't you expect your API to always return all articles, unless you filter it?
I would make sort a query string parameters, further, I would make any and all filtering query string parameters. If you look at how Stack is implemented when you click on the "Newest" questions link, you get a query string to filter the questions.
So perhaps something like:
GET http://example.com/aritcles/authors/5?sort=desc
But also think about what happens with each URL:
GET http://example.com/aritcles/ might return all current articles
GET http://example.com/aritcles/authors/ What does this url do? does it return all authors of all articles, or does it return all the articles for all authors (which is essentially the same functionality of the URL above.)
GET http://example.com/aritcles/authors/5/ might return all articles by author 5, or does it return author 5's information?
I would maybe change it to:
http://example.com/aritcles returns all articles
http://example.com/aritcles/5 returns all articles from author 5
http://example.com/authors returns all authors
http://example.com/authors/5 returns information for author 5
Alan is mostly right but his URLs are misleading. I believe the correct routes / urls should reflect the following behavior:
[GET] http://domain.com/articles #=> returns all articles (index action)
[GET] http://domain.com/articles/5 #=> returns article ID 5 (show action)
[GET] http://domain.com/authors/#=> returns all authors (index action)
[GET] http://domain.com/authors/5 #=> returns author ID 5 (show action)
[GET] http://domain.com/authors/5/articles OR http://domain.com/articles/authors/5 #=> depending on the hierarchy of your routes (both belong to the index action)
Best regards,
DBA
I have a set of actions that are returning time-series data with-in ranges specifiable to the minute.
They work fine with querystrings,
i.e.
/mycontroller/myaction?from=20091201 10:31&to=20091202 10:34
with or without URL encoded colons, but I thought it would be nice to have a pretty URL
/mycontroller/myaction/from-20091201 10:31/to-20091202 10:34
but this now strikes fear in the hear of IIS as it doesn't like colons in the URI so I get 'Bad Request' responses.
My question then, is what's a recommended/standard course of action to ensure I can keep the time in there?
Do I need to write a custom ModelBinder to parse my own datetime format? Should the actions just take strings for from and to and parse with a custom format eg "YYYYMMDD-HHmm". Can I specify a custom format somewhere? If so where? Or should I just give this up as folly and stick with querystring parameters?
Oh, and I see a lot of people go on about RESTful URLs; from what I've read there's nothing that says query strings aren't RESTful - it's more about appropriate use of existing HTTP action types.
You're right REST doesn't mean if it's its not in a folder structure its not REST.
The path structure is there to describe the resource. Querystrings can still be used to describe a filtered subset of such a resource. A date range fully qualifies as a filter criteria and should thus be perfectly RESTful being passed in as a querystring.
I have a Rails app that needs to expose values from a database as a web service - since I'm using Rails 2.x, I'm going with REST (or at least try). Assuming my resource is Bananas, for which I want to expose several sub-characteristics, consider this:
- /banana -> give a summary of the first 10 bananas, in full (all characteristics)
- /banana/?name=<name> -> give all characteristics for banana named <name>
- /banana/?number=<number> -> give all characteristics for banana number <number>
- /banana/?name=<name>/peel -> give peel data for banana named <name>
- /banana/?number=<number>/length -> give length data for banana number <number>
I don't want to search for ID, only name or number. And I have about 7 sub-characteristics to expose. Is this RESTful?
Thanks for any feedback!
What Wahnfrieden is talking about is something called Hypermedia as the Engine of Application State (HATEOAS) - a central constraint of REST as defined by Fielding.
In a nutshell, REST application clients never construct URIs themselves. Instead, they follow URIs provided by the application. So, URI templates such as the ones you're asking about are irrelevent at best. You can make them conform to a system if you'd like, but REST says nothing about how your URIs need to look. You could, if you wanted to, arrange it so that every resource in your system was available from http://example.com/{hash}.
Publishing URI templates, such as the ones you're talking about in your question, introduces tight coupling between your application and clients - something REST is trying to prevent.
The problem with understanding hypermedia-driven applications is that almost nobody implements or documents their "RESTful" systems this way.
It might help to think about the interaction between a human and server via a browser. The human only knows about content and links that the server provides through the browser. This is how a RESTful system should be built. If your resources aren't exposing links, they're probably not RESTful.
The advantage is that if you want to change your URI system, for example, to expose the Banana "Peel" attribute through a query parameter instead of a nested URL, you can do it anytime you'd like and no client code needs to be changed because they're not constructing links for themselves.
For an example of a system that embraces the hypertext-driven constraint in REST, check out the Sun Cloud API.
I would use these:
/banana
/banana/blah
/banana/123
/banana/blah/peel (and /banana/123/peel)
/banana/blah/length (and /banana/123/length)
First, common practice for ReSTful URIs is /object_name/id/verb, with some of those absent (but in that order). Of course, this is neither required nor expected.
If all your names aren't made of digits, you don't have to explicitly have name in /banana/name/blah. In fact, if anything, it would be better to have id as identifier: /banana/id/123/peel. Hope this helps.
Parameters should only be used for form submission.
Also, URI naming schemas is totally unrelated to REST. The point of REST is to make related resources discoverable via hypertext, not out-of-band conventions, and only from a limit number of entry points. So your /bananas/ entry point might provide the summary info for 10 bananas, but it must also provide the URI for each of those bananas' details resources, as well as the URI to get the summary for the next 10 bananas. Anything else is just RPC.
It is good practice in REST to not use query parameters because query parameters don´t belong to a URL and in REST all resources should be addressable through a URL.
In your example /banana/?name=name should be /banana/name because you are referring a concrete resource.
Even I think /banana/?number=number/length is not good REST style, because you are selecting an attribute through a URL when you should retrieve the whole state with /banana/name . A difference could be /customers/1024/address to get the Customer 1024 address record.
HTH.
A more opt form for the route in url having query string is the plural form, as it is possible that multiple items are returned in the result. In this case, bananas, like bananas?color=yellow, sounds more appropriate.
On the other hand, the singular form banana, like banana/123, is good when fetching a specific resource's representation when its identifier is known and query string is not required.