Sub routing best practices - rest

I am building an api which has a route: /market/items/{category}, it returns items from a category. If a user clicks on an item I have a route /item/{id}/ which returns information about the item. I'm wondering if this is a bad practice when creating a restful api. because often I would see routes like /market/items/{category}/{id}. What do you think?

If only the id is needed in order to retrieve the item (in other words, the id by itself uniquely identifies the item without any other information), then there's no reason to require a category in the URL also so this:
/item/{id}/
would be just fine for a restful API.
If, on the other hand, there are multiple types of items, each with overlapping item identifiers, then you may need something else in the URL to uniquely identify which type of item and thus which pool of item identifiers to look in.
One reason you may see some web sites doing something like this in their web page URLs:
/market/items/{category}/{id}
is for search indexing where they want the category name to be associated with the item for purposes of search engine indexing. But, if this is just a restful API, not visible web pages, then you probably aren't trying to optimize that for search hits.

Related

REST URLs for schemas and forms

I am designing an application that will expose a REST API.
URLs for the resources themselves will look fairly standard, like below:
GET /orders //Get all orders
GET /orders?somefilter=somecriteria //search for orders
GET /orders/<orderid> //specific order
PUT /orders/<orderid> //update a specific order
POST /orders //create an order
My question is regarding resources related to these. I expect the resources will mainly be accessed through an app, but still would like want to provide basic web entry forms, as well as schemas for various resources. What url should they have?
Possible urls
//Option1
GET /forms/orders //new order
GET /forms/orders/<orderid> //edit existing order
GET /schemas/orders
//Option2
GET /orders/form //new order
GET /orders/<orderid>/form //edit existing order
GET /orders/schema
//Option3
GET /orderform //new order
GET /orderform/<orderid> //edit existing order
GET /orderschema
Option 2 doesn't seem right to me, I don't think that the form resource should share the same location on a URL as the order ID. Option 1 looks the best, but would increase the organisational complexity of the app as I couldn't keep the schemas with the rest of the code dealing with a particular resource (but that is a problem that can be solved).
Is there any accepted best practice for these? It does not have to be one of the three options above, any and all pointers would be appreciated.

REST: nested resource url when you don't want the parent ID visible

I read that the route for getting a nested resource in REST should look like this
/articles/:articleId/comments
The owner (:articleId) of the child resource will be visible.
But what if you have an owner that you don't want the client to know about?
For example, let's say I have an app where users have anonymous posts. I wouldn't want other users to see the client fetching the post by /users/123/post/321 because users could identify who wrote the post from the id and it wouldn't be anonymous.
Is the id necessary? Is it ok to instead do /users/posts/321 if all posts have a unique id?
There are no actual requirements for the URL format. It can be whatever you'd like it to be.
If it were me, I would use simply /posts/321 and leave users out of it, since a particular user isn't specified in your URL at all. I think that's the clearest way to handle it in your case.

Rest API Hateoas : Should API response have identifiers as hard coded or as placeholders?

Link to the HATEOAS This is the link to the Hateoas article (snapshot below) where the identifiers of the resource is part of the URL i.e. 12345. Here the API response has the final API relative URL i.e. /accounts/12345/deposit and the client just needs to hit it.
Link to the Github Users API This is the link to the Github API (snapshot below) where there are lots of placeholders for identifiers. How will clients modify these URLSs and add a value in these placeholders? For example, {/gist_id}, {/other_user}.
Isn't passing the URL with id value instead of placeholder better? Why and when to rely on different clients to add values in these placeholders?
Hypertext as the engine of application state (HATEOAS) is a bit more than just the usage of links. In essence it enforces the interaction model that is used on the Web for two decades quite successfully. On the web a server usually "teaches" clients (browsers) to achieve something via the help of link relations, that can be used to automatically download related resources or give a hint on the reference resource, and Web forms, that define the syntax and semantics of each of the respective supported (input) elements, i.e. a text field, an option element to select one or multiple choices, a drop down or even a slider widget. Based on the affordance of each of the elements a client knows i.e. that a button wants to be clicked or pressed while a text fields wants some user input and stuff or a link annotated with the prefetch link relation name may be downloaded automatically once the current page finished loading as a client might invoke it next or a preload link relation might instruct a user agent to load the referenced resource early in the current page loading process.
The form not only teaches a client about the supported fields a resource has but also about the target URI to send the request to, the HTTP method to use wile sending the request as well as the media-type, which in the case of Web forms is usually implicitly set to application/x-www-form-urlencoded.
In an ideal world a client just uses the information given by the server. Unfortunately, the world isn't perfect and over time people have come up with plenty of other solutions. Among one of them is URI templating that basically allows clients to use a basic URI and fill out certain placeholders with concrete values. As making use of templating requires some knowledge of the URIs intention or the parameters you need to pass, such capabilities make only sense as part of media-type support.
Plain JSON (application/json) has by default no support for URIs whatsoever and as such a user agent receiving a plain JSON payload might not be able to automatically replace a template URI with a concrete one out of the box. JSON Hyper-Schema (application/schema+json) attempts to add link and URI template support to plain JSON payloads. A user client though needs to be hinted with the appropriate media-type in order to automatically resolve the full URI. As such, the user agent also has to support that respective media type otherwise it won't be able to process the document (resolve the template URI to a real URI) successfully.
JSON Hypertext Application Language a.k.a HAL JSON also supports URI templates for links. application/collection+json does support two kinds of templates - query templates and objects-template. The primer one is similar to a URI template by allowing to append certain query parameters to the target URI upon sending the request while the latter one allows to define a whole object that contains all the input elements used to add or edit an item within the collection. JSON-LD does not really support URI templating AFAIK though it uses the concept of a so called context where certain terms can be used to abbreviate URIs. As such something like name can be used within the context for a URI like http://schema.org/name.
As you can hopefully see, the support for URI templating depends on the media-type used for exchanging data. In the case of the outlined github example GET /users/:username this more or less resembles a typical Web API documentation, similar as it is done in a Swagger API documentation, that unfortunately has hardly anything to do with HATEOAS.
For your top example (banking), you should absolutely include the complete URL, with account numbers (IDs), so that the client does not need to translate/substitute anything. This is the most common scenario with HATEOAS. However, GitHub does have those "placeholders" for endpoints that could contain multiple values. You can't include the "following_url" for every user in the response, it's not practical. So you have to determine the "other_user" value another way and make the substitution. Personally, I haven't even had this use case with any of my applications and all of my HATEOAS URLs resemble you first example (though I prefer full URLs not relative). Unless you have specific cases like GitHub does, it's not necessary to use any of these placeholders. Even GitHub only uses that where they could be multiple values. For fixed value URLs, they have the username (like your account number) in the URL ("octocat").
According to me we should not give the direct url in the body
We should always parameterized the api and get details form there.
In simple case if Id of data change than every time data need to update for detail url.
Else if it’s dynamic you will never face this issue.
And this also come under best practices.

RESTful URL for search vs admin

I have a scenario where I have to either
Pull the data from backend as search
Pull the same data from backend to administrate
The URLs I am using are -
/cars
/cars/management
The search can be then subsequently filtered as
/cars?color=blue
The concern that I have is that management is not a resource - it is actually an action. The management page contains links for other functionality associated with car management [add a car/delete a car/list cars/modify cars etc]
Has somebody else faced this issue? Can you let me know your solution?
There is nothing wrong with having a management resource that is a page showing management options for cars. Just because "cars" is the only thing in your database doesn't mean that is the only resource you can present to the user. You could have a resource that is just a form to pick a color (that makes a POST or PUT to the car resource). You could have a resource that is just a form to fill out the address you want the car delivered to. You could have a resource that is just a check box whether you want leather seats or not. You can have as many resources as you like and that make sense, even if all the resources are are pages with forms or links back to the car resource.
Just don't put any verbs in your URLs. You should still be using state transfer using HTTP verbs to change the state of the resources. Don't have a link like
GET /cars/123/deleteCar
on the management page. Instead there might be a link on the management page that (probably using Javascript since browsers have poor native support for HTTP verbs) performs a HTTP request along the lines of
DELETE /cars/123
when the user clicks the link. Something like jQuery can help with that. So long as the management page is using the HTTP verbs to change the state of the resources you are following REST since HTTP is a REST constrained protocol. REST doesn't say don't have actions, it says the actions should be constrained to state transfer.
There is no such concept as a "RESTful URL";
There is no issue with your URLs(/cars, /cars/management)
"/cars/management" is valid resource and it is not an action at all.
The RESTfull way to do this is to use the same URL with different HTTP verbs:
GET /cars for search/listing.
POST /cars for insert.
PUT /cars?id=123 (or /cars/123) for update.
DELETE /cars?id=123 for delete.

REST URI Design for resources that belong to a specific user

Assume I want to create a very simple todolist RESTful API, where each user owns a list of todos. The user is already authenticated over http BASIC or DIGEST.
At this point I am not sure what the URL scheme should look like.
Would it be:
http://servername/todos/
where my server filters the appropriate todos according to the authentification given to me by the http header.
Or should I include the username in the URI instead:
http://servername/users/username/todos/
On some websites I have even seen that they hand over the user name as a parameter like this:
http://servername/todos?username=babsi
As far as I can tell all three choices are stateless as I always receive the username, but just over different sources. From what I can tell to make sure that the URI is accessed by the proper user I always need to check the http header anyways. So which of the ways would you consider the best URI design in REST or should I do in a different way entirely?
You can use the following:
http://servername/todos/ GET list all todos
http://servername/users/ GET list all users
http://servername/users/{user_id}/ GET list an user
http://servername/users/{user_id}/todos/ GET list all todos for an user
I think the point here is how you want to design the relationships between your resources, if a todo just can exist in the context of an user use a hierarchy like approach as above.
As general rule i usually follow this:
Use path variables to encode hierarchy: /parent/child
Put punctuation characters in path variables to avoid implying hierarchy where
none exists: /parent/child1;child2
Use query variables to imply inputs into an algorithm, for
example: /search?q=jellyfish&start=20
Having the username in the URL depends on what you want to do (if anything at all) when you receive a request where the username in the URL does not match the authentication. If you want to re-authorize the user in this situation then yes - it's OK to have the username in the URL, otherwise it's OK to have it just in your header or other authentication scheme if there is no such need.
One fairly common example of a valid requirement would be if you have to have a main user (or group of such users) that can impersonate other users.
When the user in question is always the user who is holding the authentication token, then use something like "me" in your path.
http://example.com/users/me/<path-to-inner-resource>
Otherwise, user should be treated just like any other resource in your system, in which case the resource identifier for that user becomes a part of the path.
http://example.com/users/<id>/<path-to-inner-resource>
Take a look at Twitter APIs as an example.
https://developer.twitter.com/en/docs/twitter-api/users/follows/quick-start/follows-lookup