Let's take the following resource in my REST API:
GET `http://api/v1/user/users/{id}`
In normal circumstances I would use this like so:
GET `http://api/v1/user/users/aabc`
Where aabc is the user id.
There are times, however, when I have had to design my REST API in a way that some extra information is passed with the ID. For example:
GET `http://api/v1/user/users/customer:1`
Where customer:1 denotes I am using an id from the customer domain to lookup the user and that id is 1.
I now have a scenario where the identifier is more than one key (a composite key). For example:
GET `http://api/v1/user/users/customer:1;type:agent`
My question: in the above URL, what should I use as the separator between customer:1 and type:agent?
According to https://www.ietf.org/rfc/rfc3986.txt I believe that the semi-colon is not allowed.
You should either:
Use parameters:
GET http://api/v1/user/users?customer=1
Or use a new URL:
GET http://api/v1/user/users/customer/1
But use Standards like this
("Paths tend to be cached, parameters tend to not be, as a general rule.")
Instead of trying to create a general structure for accessing records via multiple keys at once, I would suggest trying to think of this on more of a case-by-case basis.
To take your example, one way to interpret it is that you have multiple customers, and those customers each may have multiple user accounts. A natural hierarchy for this would be:
/customer/x/user/y
Often an elegant decision like this can be made, that not only solves the problem but also documents your data-model in a way that someone can easily see that users belong to customers via a 1-to-many relationship.
Related
I'm rewriting an API to be more RESTful, but I'm struggling with a design issue. I'll explain the situation first and then my question.
SITUATION:
I have two sets resources users and items. Each user has a list of item, so the resource path would like something like this:
api/v1/users/{userId}/items
Also each user has an isPrimary property, but only one user can be primary at a time. This means that if I want to get the primary user you'd do something like this:
api/v1/users?isPrimary=true
This should return a single "primary" user.
I have client of my API that wants to get the items of the primary user, but can't make two API calls (one to get the primary user and the second to get the items of the user, using the userId). Instead the client would like to make a single API call.
QUESTION:
How should I got about designing an API that fetches the items of a single user in only one API call when all the client has is the isPrimary query parameter for the user?
MY THOUGHTS:
I think I have a some options:
Option 1) api/v1/users?isPrimary=true will return the list of items along with the user data.
I don't like this one, because I have other API clients that call api/v1/users or api/v1/users?isPrimary=true to only get and parse through user data NOT item data. A user can have thousands of items, so returning those items every time would be taxing on both the client and the service.
Option 2) api/v1/users/items?isPrimary=true
I also don't like this because it's ugly and not really RESTful since there is not {userId} in the path and isPrimary isn't a property of items.
Option 3) api/v1/users?isPrimary=true&isShowingItems=true
This is like the first one, but I use another query parameter to flag whether or not to show the items belonging to the user in the response. The problem is that the query parameter is misleading because there is no isShowingItems property associated with a user.
Any help that you all could provide will be greatly appreciated. Thanks in advance.
There's no real standard solution for this, and all of your solutions are in my mind valid. So my answer will be a bit subjective.
Have you looked at HAL for your API format? HAL has a standard way to embed data from one resources into another (using _embedded) and it sounds like a pretty valid use-case for this.
The server can decide whether to embed the items based on a number of criteria, but one cheap solution might be to just add a query parameter like ?embed=items
Even if you don't use HAL, conceptually you could still copy this behavior similarly. Or maybe you only use _embedded. At least it's re-using an existing idea over building something new.
Aside from that practical solution, there is nothing in un-RESTful about exposing data at multiple endpoints. So if you created a resource like:
/v1/primary-user-with-items
Then this might be ugly and inconsistent with the rest of your API, but not inherently
'not RESTful' (sorry for the double negative).
You could include a List<User.Fieldset> parameter called fieldsets, and then include things if they are specified in fieldsets. This has the benefit that you can reuse the pattern by adding fieldsets onto any object in your API that has fields you might wish to include.
api/v1/users?isPrimary=true&fieldsets=items
Suppose there's USERS and ORDERS
for a specific user's order list
You could do
/user/3/order_list
/order/?user=3
Which one is prefered and why?
Optional parameters tend to be easier to put in the query string.
If you want to return a 404 error when the parameter value does not correspond to an existing resource then I would tend towards a path segment parameter. e.g. /customer/232 where 232 is not a valid customer id.
If however you want to return an empty list then when the parameter is not found then query string parameters. e.g. /contacts?name=dave
If a parameter affects an entire URI structure then use a path e.g. a language parameter /en/document/foo.txt versus /document/foo.txt?language=en
If unique identifiers to be in a path rather than a query parameter.
Path is friendly for search engine/browser history/ Navigation.
When I started to create an API, I was thinking about the same question.
Video from apigee. help me a lot.
In a nutshell when you decide to build an API, you should decide which entity is independent and which is only related to someone.
For example, if you have a specific endpoint for orders with create/update/delete operations, then it will be fine to use a second approach /order/?user=3.
In the other way, if orders have only one representation, depends on a user and they don't have any special interaction then you could first approach.
There is also nice article about best practice
The whole point of REST is resources. You should try and map them as closely as possible to the actual requests you're going to get. I'd definitely not call it order_list because that looks like an action (you're "listing" the orders, while GET should be enough to tell you that you're getting something)
So, first of all I think you should have /users instead of /user, Then consider it as a tree structure:
A seller (for lack of a better name) can have multiple users
A user can have multiple orders
An order can have multiple items
So, I'd go for something like:
The seller can see its users with yourdomain.com/my/users
The details of a single user can be seen with yourdomain.com/my/users/3
The orders of a single user can be seen with yourdomain.com/my/users/3/orders
The items of a single order can be seen with yourdomain.com/my/users/3/orders/5
Your backend has two Models:
One Company to Many Employees.
You want to accomplish the following:
Get all Companies
Get a Company by ID
Get all Employees for a Company
Get all Employees
Get a Employee by ID
What is the best practice for handling the REST URLs when your models have 1:M relationships? This is what I have thought of so far:
/companies/
/companies/<company_id>/
/companies/<company_id>/employees/
/employees/
/employees/id/<employee_id>/
Now let's pretend One Company has Many Models. What is the best name to use for "Adding an employee to a Company" ? I can think of several alternatives:
Using GET:
/companies/<company_id>/add-employee/<employee_id>/
/employees/<employee_id/add-company/<company_id>/
Using POST:
/companies/add-employee/
/employees/add-company/
The URIs look fine to me, except maybe the last one, that does not need an additional "id" in the path. Also, I prefer singular forms of words, but that is just me perhaps:
/company/
/company/<company_id>/
/company/<company_id>/employee/
/employee/
/employee/<employee_id>/
The URIs do not matter that much actually, and can be changed at any point later in time when done properly. That is, all the URIs are linked to, instead of hardcoded into the client.
As far as adding an employee, I would perhaps use the same URIs defined above, and the PUT method:
PUT /employee/123
With some representation of an employee. I would prefer the PUT because it is idempotent. This means, if the operation seems to fail (timeout, network error occurs, whatever) the operation can be repeated without checking whether the previous one "really" failed on the server or not. The PUT requires some additional work on the server side, and some additional work to properly link to (such as forms), but offers a more robust design.
As an alternative you can use
POST /employee
With the employee representation as body. This does not offer any guarantees, but it is easier to implement.
Do not use GET to add an employee (or anything for that matter). This would go against the HTTP Specification for the GET method, which states that it should be a pure information retrieval method.
GET https://api.website.com/v1/project/employee;company-id={company-id},
title={title-id}?non-smoker={true|false}&<name1>=<value1>&<name2>=<value2>&<name3>=<value3>
where:
company-id is mandatory,
title is optional
name/value can be any filter criteria.
Is there a better way to define the interface?
This API is not supposed to create an employee object. It is for getting an array of employee objects that belongs to a particular company and has a particular title and the other filter criteria.
I don't know if there is a better way, because it depends often on the technology you use and its idioms.
However, here is two different URI designs that I like (and why)
#1 GET https://api.website.com/v1/project/employee/{company-id}?title={title-id}&non-smoker={true|false}&<name1>=<value1>&<name2>=<value2>&<name3>=<value3>
#2 GET https://api.website.com/v1/project/company/{company-id}/employee?title={title-id}&non-smoker={true|false}&<name1>=<value1>&<name2>=<value2>&<name3>=<value3>
As you can see in both example I extracted company-id from the query string. I prefer to add mandatory parameters in the path info to distinguish them. Then, in the second URI, the employee ressource is nested in the company. That way you can easily guess that you can retrieve all employee from a specific company, which is not obvious in the first example.
This api is supposed to GET employee objects that satisfy the given criteria of belonging to a particular company, having particular job title and some other filter criteria.
Personally I would just design your URI as http://acme.com/employee/?company=X&title=Y&non-smoker=Z&T=U. I wouldn't write "in stone" that the company is mandatory: your API will be easier to change.
However, you should consider that few "big" requests are far faster than plenty of small ones. Moreover, URI representations can be effectively cached. Therefore it is often better to have URIs based on IDs (since there are more chances that they will be asked again).
So you could get the complete employee list of a company (plus other data about the company itself) with http://acme.com/company/X and then filter it client-side.
Are you creating a new employee object? If so then a POST (create) is more appropriate. A good clue is all the data you're pushing in the URL. All that should be in the body of the POST object.
Simple question I'm having trouble finding an answer to..
If I have a REST web service, and my design is not using url parameters, how can I specify two different keys to return the same resource by?
Example
I want (and have already implemented)
/Person/{ID}
which returns a person as expected.
Now I also want
/Person/{Name}
which returns a person by name.
Is this the correct RESTful format? Or is it something like:
/Person/Name/{Name}
You should only use one URI to refer to a single resource. Having multiple URIs will only cause confusion. In your example, confusion would arise due to two people having the same name. Which person resource are they referring to then?
That said, you can have multiple URIs refer to a single resource, but for anything other than the "true" URI you should simply redirect the client to the right place using a status code of 301 - Moved Permanently.
Personally, I would never implement a multi-ID scheme or redirection to support it. Pick a single identification scheme and stick with it. The users of your API will thank you.
What you really need to build is a query API, so focus on how you would implement something like a /personFinder resource which could take a name as a parameter and return potentially multiple matching /person/{ID} URIs in the response.
I guess technically you could have both URI's point to the same resource (perhaps with one of them as the canonical resource) but I think you wouldn't want to do this from an implementation perspective. What if there is an overlap between IDs and names?
It sure does seem like a good place to use query parameters, but if you insist on not doing so, perhaps you could do
person/{ID}
and
personByName/{Name}
I generally agree with this answer that for clarity and consistency it'd be best to avoid multiple ids pointing to the same entity.
Sometimes however, such a situation arises naturally. An example I work with is Polish companies, which can be identified by their tax id ('NIP' number) or by their national business registry id ('KRS' number).
In such case, I think one should first add the secondary id as a criterion to the search endpoint. Thus users will be able to "translate" between secondary id and primary id.
However, if users still keep insisting on being able to retrieve an entity directly by the secondary id (as we experienced), one other possibility is to provide a "secret" URL, not described in the documentation, performing such an operation. This can be given to users who made the effort to ask for it, and the potential ambiguity and confusion is then on them, if they decide to use it, not on everyone reading the documentation.
In terms of ambiguity and confusion for the API maintainer, I think this can be kept reasonably minimal with a helper function to immediately detect and translate the secondary id to primary id at the beginning of each relevant API endpoint.
It obviously matters much less than normal what scheme is chosen for the secret URL.