Handling contextual links from restful api in vuejs - rest

Apparently I haven't used the correct search terms, because I can't find anything like my issue..
In Vuejs I use axios tot consume a restful API, the results can contain contextual links to ie complete a task. How do I handle these GET requests from the frontend?
This is what my response looks like:
{
"id": 2,
"description": "iPhone",
"status": "IN_PROGRESS",
"_links": {
"self": {
"href": "http://localhost:8090/orders/2"
},
"orders": {
"href": "http://localhost:8090/orders"
},
"cancel": {
"href": "http://localhost:8090/orders/2/cancel"
},
"complete": {
"href": "http://localhost:8090/orders/2/complete"
}
}
}
I've tried this (which obviously doesn't get me the needed result):
<md-table v-model="orders" :table-header-color="tableHeaderColor">
<md-table-row slot="md-table-row" slot-scope="{ item }">
<md-table-cell md-label="Description">{{
item.description
}}</md-table-cell>
<md-table-cell md-label="Status">{{ item.status }}</md-table-cell>
<md-table-cell md-label="Action">
<a v-if="item._links.complete" :href="item._links.complete.href">
Complete
</a>
</md-table-cell>
</md-table-row>
</md-table>
All I did find some information about is binding links to the router.. But that all seems to be about non conditional links, my API can omit certain links if they don't apply.

Add to your link this:
<a v-if="item._links.complete" :href="#" #click.prevent="clickHandler($event, item._links.complete.href)">
Within your vue component methods add new method:
methods:{
clickHandler(event, yourUrl){
axios.get(yourUrl)
.then(function (response){
//do what you need with this response
}
}
}

Related

Return several resources in REST call

I am providing access to a REST endpoint where some aggregates are computed.
Let's say the model is as follows:
Purchase:
amount: amount spent
group: one of ELECTRONICS, FOOD, FURNITURE, ...
date: purchase date
Now I want to offer a timeline of purchases, aggregated on a weekly basis, and partitioned by group. This will produce the following data:
{
"ELECTRONICS": [{"week": "2018WK1", "amount": 1000.0}, ...],
"FOOD": [{"week": "2018WK1", "amount": 2000.0}, ...],
"FURNITURE": [{"week": "2018WK1", "amount": 3000.0}, ...],
...
}
Some things to note:
the number of groups is not known in advance (it depends on the stored data)
since this is computed data, I would like to return the whole thing in one single request, instead of having to do the aggregates for each of the groups in separate requests
The URL for the request would be something like: /api/weekly_purchases/2018
How can I offer these kind of resources in a REST API?
Return several resources in REST call
How would you do it as a web page?
Somewhere on your web site would be a link, with text "this week's summary" (or whatever the appropriate concept is in the language of your domain). If a user clicked that link, the browser would do a GET on one URL, which would go to the server, aggregate all of the data together, and return the result.
So do that?
REST doesn't care about the spelling of the URI (the browser doesn't try to interpret the URL, except in very shallow generic ways), so /api/weekly_purchases/2018 is fine.
The trick is recognizing that a report summarizing purchases in the current fiscal year, broken out by week, is a resource. It may have data in it that duplicates the information in other resources, even data in many other resources, but it is still a resource itself.
As already mentioned in my initial comment or by VoiceOfUnreason the same techniques that apply to the browser-based Web apply to any interaction model used by applications that follow the REST architecture principles. As also mentioned by VoiceOfUnreason a client would initially request some state returned from the entry-point, i.e. https://api.acme.com that will return a collection of links a client can use to progress its task. In order for the client to determine which URL to invoke the response should give the URI a meaningful name (link-relation name). IANA maintains a list of already specified link-relation names you should use if possible or define your own one in further standards. According to Fielding the specification of media-types and link relations is one of the most important things to do if developing a RESTful architecture.
For simplicity I use a simplified HAL-JSON syntax throughout the example.
{
...
"_links": {
"self": {
"href": "https://api.acme.com"
},
...
"archives": {
"href": "https://api.acme.com/weekly_purchases"
},
...
}
}
According to the HTML 5 spec archives
indicates that the referenced document describes a collection of records, documents, or other materials of historical interest
The link relation name therefore describes the intent of the URI which client can use if interested in retrieve a collection of historical entries. The client does not really have to know the exact URI as he will learn it by simply following the link relation's target href element. This allows the server to change its internal URI structure anytime it has to without actually breaking clients.
On following the archives target URI a client will not really know yet how the actual data has to be retrieved as the URI and the link relation name are to generic. But the server will guide the client through its task. A response on the invocation of the abovementioned target URI might return the following content:
{
"year": [
"2018": {
"_links": {
"chapter": {
"href": "https://api.acme.com/weekly_purchases/2018"
}
}
},
"2017": {
"_links": {
"chapter": {
"href": "https://api.acme.com/weekly_purchases/2017"
}
}
},
...
"2014": {
"_links": {
"chapter": {
"href": "https://api.acme.com/weekly_purchases/2014"
}
}
}
],
"_links": {
"self": {
"href": "https://api.acme.com/weekly_purchases"
},
"first": {
"href": "https://api.acme.com/weekly_purchases"
},
"next": {
"href": "https://api.acme.com/weekly_purchases?p=1"
},
"last": {
"href": "https://api.acme.com/weekly_purchases?p=3"
},
"current": {
"href": "https://api.acme.com/weekly_purchases"
}
}
}
This response basically only teaches the client that there are multiple years available to choose from and the client has to decide which year s/he is interested in an invoke that URI to proceed its task. The next, last and first link relation indicate that there are multiple pages available as only the 5 years per page are returned. The current link relation name will always point to the most recent entry in the collection, which is the initial page (or first page) of the collection-resource. Note further how multiple different link-relation names may point to the same URI. Sometimes it isn't really clear which link relation names to use as their semantics partly overlap. This is just an example on what can be done with link relation names.
A client can now further drill down to the purchases done in 2018 by following the chapter link for 2018. A response on invoking that URI may now look like this:
{
"purchase": [
"W1": {
"sum": 1263.59,
"currency": "Euro",
"_links": {
"about": {
"href": "https://api.acme.com/weekly_purchases/2018/1"
}
}
},
"W2": {
"sum": 569.32,
"currency": "Euro",
"_links": {
"about": {
"href": "https://api.acme.com/weekly_purchases/2018/2"
}
}
},
...
"W48": {
"sum": 72.98,
"currency": "Euro",
"_links": {
"about": {
"href": "https://api.acme.com/weekly_purchases/2018/48"
}
}
},
"current": {
"sum": 72.98,
"currency": "Euro",
"_links": {
"about": {
"href": "https://api.acme.com/weekly_purchases/2018/48"
}
}
}
],
"_links": {
"index": {
"href": "https://api.acme.com/weekly_purchases"
},
"self": {
"href": "https://api.acme.com/weekly_purchases/2018"
},
"current": {
"href": "https://api.acme.com/weekly_purchases/2018"
},
"prev": {
"href": "https://api.acme.com/weekly_purchases/2017"
},
"prev-archive": {
"href": "https://api.acme.com/weekly_purchases/2017"
},
"first": {
"href": "https://api.acme.com/weekly_purchases/2000"
}
}
}
You could either add content here to the weekly summary or hide it down the road by following the about link only if clients are really interested in such details.
Note further: As weekly_purchases is just a string without meaning to the client it does not really know what it means. You could therefore also rename it to purchase-archive or something like that and introduce a further choice to the client and let the client determine whether it wants a weekly, monthly or total summary of that year.
REST is about providing choices to a client and teach it what the actual choices are intended for. One of the aims the RESTful architecture tries to solve is the strict coupling between clients and servers which prevent the latter one from evolving freely and the former ones to break if the latter one changes unexpectedly. This decoupling only works if certain standards are used to increase the likelihood for interoperability. Usually out-of-band information (pre-existing knowledge about the API and how to interact with it) is leading to a coupling. Even Fielding stated that some prior knowledge is needed though but not encoded directly into the application but on reusing certain standards like well-defined and stable media-types and link-relation names.

How to specify what operations (Http Methods) is available with HATEOAS

The HATEOAS definition say that each response must contains the associated links, but following the REST pattern an URI must be the same for all operations, what changes is the HTTP method.
Per example:
Request: GET http://example.com/book
Response:
[
{
"id": 1,
"title:" "foo",
"links": {
"self": http://example.com/book/1
}
}
]
The response inform that the link that can be used to read the book data is "http://example.com/book/1", but with only this link i unknown if the user that did this request is authorized to do a DELETE or PUT for this resource.
The HATEOAS or other specification define some pattern for inform what methods are available for each resource?
Per example:
Request: GET http://example.com/book
Response:
[
{
"id": 1,
"title:" "foo",
"links": {
"self": {
"url": "http://example.com/book/1",
"methods": [
"GET",
"PUT",
"DELETE"
]
}
}
]
You should look for Siren (http://hyperschema.org/mediatypes/siren)
It will tell your clients what methods do they can use with links.

RIPE: How to lookup IP Address using REST API

As per the RIPE REST API documentation, one needs to specify the requests in the following format:
http://rest.db.ripe.net/{source}/{objecttype}/{key}
So I am assuming that looking up an IP address will be like this:
http://rest.db.ripe.net/ripe/inetnum/193.0.6.142.json
However, the response I get is :
{
"link": {
"type": "locator",
"href": "http://rest.db.ripe.net/ripe/inetnum/193.0.6.142"
},
"errormessages": {
"errormessage": [
{
"severity": "Error",
"text": "ERROR:101: no entries found\n\nNo entries found in source %s.\n",
"args": [
{
"value": "RIPE"
}
]
}
]
},
"terms-and-conditions": {
"type": "locator",
"href": "http://www.ripe.net/db/support/db-terms-conditions.pdf"
}
}
What am I doing wrong ?
You are using the wrong URL, the correct URL for your example query would be:
http://rest.db.ripe.net/search.json?query-string=193.0.0.0/21&flags=no-filtering
Or this for XML:
http://rest.db.ripe.net/search.xml?query-string=193.0.0.0/21&flags=no-filtering
Looks like https://rest.db.ripe.net/search.json?query-string=193.0.6.142 is the correct link to use. This seems to return back the same data as I see on ripe.net
You didn't write {key} part right. Inetnum objects on RIPE have "193.0.0.0 - 193.0.7.255" type of key. You must make a request like this:
https://rest.db.ripe.net/ripe/inetnum/91.123.16.0 - 91.123.31.255

Spring Data Rest - Multiple endpoints

I’m working on a Spring Data Rest project and would like a way to effectively ‘split’ my API off two base roots / endpoints. For example, consider the root below:
{
"_links": {
"orders": {
"href": "http://localhost:8080/orders{?page,size,sort,projection}",
"templated": true
},
"customers": {
"href": "http://localhost:8080/customers{?page,size,sort,projection}",
"templated": true
},
"profiles": {
"href": "http://localhost:8080/profiles{?page,size,sort,projection}",
"templated": true
}
}
}
Now assume that I don’t really want my API consumers to mess with the profiles resource (they still technically can but its unsupported) but I still need it as part of my Rest API as my UI uses it. So what I really want is to base some of my APIs under “public/” and others under “internal/”
I.e.
{
"_links": {
"orders": {
"href": "http://localhost:8080/public/orders{?page,size,sort,projection}",
"templated": true
},
"customers": {
"href": "http://localhost:8080/public/customers{?page,size,sort,projection}",
"templated": true
},
"profiles": {
"href": "http://localhost:8080/internal/profiles{?page,size,sort,projection}",
"templated": true
}
}
}
The problem I have is that this doesn’t work as I believe Spring Data assumes the second level off my base (/) is the internal sub-resource. Is there any way I can achieve the above using Spring Data Rest?
Typically if you want to customize the response you will want to utilize the Spring HATEOAS project.

How should a server respond to a GET request for a resource that is an unbounded collection in a REST API?

Consider the following URIs where the server returns a representation corresponding to the nth Fibonacci number.
GET /fib/0 ==> { value: 0, _links: { next: { href: '/fib/1' } } }
GET /fib/1 ==> { value: 1, _links: { next: { href: '/fib/2' } } }
GET /fib/2 ==> { value: 1, _links: { next: { href: '/fib/3' } } }
...
GET /fib/73 ==> { value: 806515533049393, _links: { next: { href: '/fib/74' } } }
... etc ...
Given the constraints of a strict interpretation of REST, what should the server return when it receives the following request?
GET /fib
Wikipedia says to return the collection members as links, optionally with details of each member. Obviously you cannot return the whole collection in this case, because it is unbounded. The RESTful APIs we have built with large collections will return the collection paginated. I don't know if this would be a useful thing to return in your use case, but I see you are using HAL, so if you were to, it could look like this for linked data:
{
"_links": {
"self": { "href": "/fib?page=2" },
"next": { "href": "/fib?page=3" },
"prev": { "href": "/fib?page=1" },
"fibs": [
{"href": "/fib/4" },
{"href": "/fib/5" },
{"href": "/fib/6" }
},
}
or this for embedded:
{
"_links": {
"self": { "href": "/fib?page=2" },
"next": { "href": "/fib?page=3" },
"prev": { "href": "/fib?page=1" },
},
_embedded: {
"fibs": [
{
"_links": {"self": "/fib/4" },
"value": 2
},
{
"_links": {"self": "/fib/5" },
"value": 3
},
{
"_links": {"self": "/fib/6" },
"value": 5
}
}
}
You can see a similar example to this in the HAL spec: https://datatracker.ietf.org/doc/html/draft-kelly-json-hal-00#section-6
If the user doesn't specify the page query string param, we return the first page.
If returning the collection (paginated or in it's entirety) doesn't make sense, then I would recommend returning a 405 Method Not Allowed HTTP response code. If you cannot insert items (POST) into the collection either, then maybe return the same 405 response for that too.
The server should return a resource that is represented by /fib or 404 if no such resource is defined/exists. What the resource actually IS depends on the domain and requirements of your application.
According to W3's Dereferencing HTTP URIs, because I cannot return an infinite sequence, it looks like I should return an HTTP 303 - See Other redirect to another URI (e.g. /fib/Information) which contains additional related information about the Fibonacci sequence such as a human-readable description, an algorithm to compute it, or an RDF description of the aggregation. I should support content negotiation to allow consumers to select an appropriate representation.