[aerogear-dev] Paging Demo
Daniel Manzke
daniel.manzke at googlemail.com
Fri Jan 11 07:36:32 EST 2013
I have to say I like all proposals. Having access to the informations in
the json is the facebook way. It is easy to build an graph explorer. No
need to get low level.
On the other hand, if you want to be more consistent, I would go the way of
the last proposal. I think this is in a more common sense to http. Think
about the Range header, which is used for downloading.
You specify what part you want to have.
If you use headers they should start with X-My-Header. So it is separated
of the standard headers and marked as extension.
Last but not least, I always like the Content-Negotiation way, where you
can have a url like ".../download/myfile.pdf" which would translate to only
accept pdfs (@Produces). It can also be used for sending xml instead of
json. (default with json "/cars" and specific would be "/cars.json" or
"/cars.xml".
Bye,
Daniel
2013/1/11 Kris Borchers <kris at redhat.com>
>
> On Jan 11, 2013, at 5:01 AM, Daniel Bevenius <daniel.bevenius at gmail.com>
> wrote:
>
> Hey Kris,
>
> been thinking about your reply regarding the inconsistency of the returned
> data. I think it looks a little odd to have the 'cars' property returned
> when requesting a single car.
> What do you all think of this as a suggestion below?
>
>
> I'm sorry, I misread that e-mail and thought these were both requests to
> the /cars endpoint and the data returned was formatted differently based on
> the data length. What you have makes sense so disregard what I said.
>
>
> As you can see we now return HTTP Headers and also the object returned is
> either an array of cars, or just a single object if you only request a
> single car.
>
> Getting a page of Cars
>
> URL="http://controllerdemo-danbev.rhcloud.com/aerogear-controller-demo"
> curl -i --header "Accept: application/json" "$URL/cars?page=0&perPage=4"
>
> The request will return:
>
> HTTP/1.1 200 OKLink-Previous: cars?page=0&page=4
>
> IMO, if we are on the first page the Link-Previous header should be empty
> since there is no previous page. That will make it easier for people
> building the UI to know if they should show a previous link, etc. Also, you
> can't have two parameters with the same name, should that actually be
> page=0&perPage=4?
>
> Link-First: cars?page=0&page=4
>
> Same thing, page/perPage?
>
> MetaData-PerPage: 4MetaData-Page: 0Link-Next: cars?page=1&page=4
>
> Same as previous, if we are on the last page, there should not be a value
> for Link-Next. Also, as above, page/perPage?
>
> Content-Type: application/json;charset=UTF-8Content-Length: 161[
> {"color":"Black","brand":"BMW","id":1},
> {"color":"Red","brand":"Ferrari","id":2},
> {"color":"Blue","brand":"Skoda","id":3},
> {"color":"Green","brand":"Audi","id":4}]
>
> <https://gist.github.com/4500336#getting-the-next-page-of-cars> Get a
> single Car
>
> URL="http://controllerdemo-danbev.rhcloud.com/aerogear-controller-demo"
> curl -i --header "Accept: application/json" "$URL/cars/1"
>
> The request will return:
>
> {"color":"Black","brand":"BMW","id":1}
>
>
>
> On 10 January 2013 20:00, Daniel Bevenius <daniel.bevenius at gmail.com>wrote:
>
>> Summers brought up a good point today on IRC which I've forgot to
>> mention. We've said that it will be possible to pass the page parameters as
>> HTTP Headers and this is still the plan. But the demo is using the lastest
>> from upstream and support for passing headers to the client is not there
>> yet. I hope to have this working shortly though and I'll post back with
>> information as soon as possible, tomorrow or Monday at the latest.
>>
>>
>>
>>
>> On 10 January 2013 15:32, Daniel Bevenius <daniel.bevenius at gmail.com>wrote:
>>
>>> >I know it's just a demo but I think making that JSON format consistent
>>> so that the car data is always in an array under the "cars" key would be
>>> better.
>>> Good point. I'll change this so that there is always a "cars' key.
>>>
>>>
>>> On 10 January 2013 15:13, Kris Borchers <kris at redhat.com> wrote:
>>>
>>>>
>>>> On Jan 10, 2013, at 3:02 AM, Daniel Bevenius <daniel.bevenius at gmail.com>
>>>> wrote:
>>>>
>>>> We talked about paging yesterday on IRC, and it was decided to add a
>>>> paging example to aerogear-controller-demo. What follows is an example to
>>>> kick of further discussion about what the example should look like.
>>>>
>>>> AeroGear Controller Demo Paging Route
>>>>
>>>> This page discusses AEROGEAR-795<https://issues.jboss.org/browse/AEROGEAR-795> which
>>>> is about adding an example to aerogear-controller-demo to demonstrate
>>>> paging support so that the client libraries (Android, JavaScript, and iOS)
>>>> can be tested against it.
>>>>
>>>> This is only a suggestion and the implementation and the names of the
>>>> query parameters can all be changed.
>>>> Use case
>>>>
>>>> The example is using cars as the resource to interact with. To be able
>>>> to query we need something to query, so lets start by adding some cars by
>>>> posting.
>>>> Adding Cars
>>>>
>>>> URL="http://controllerdemo-danbev.rhcloud.com/aerogear-controller-demo"
>>>>
>>>> curl -i --header "Accept: application/json" -H "Content-type: application/x-www-form-urlencoded" --data "car.color=Black&car.brand=BMW" -X POST "$URL/cars"
>>>> curl -i --header "Accept: application/json" -H "Content-type: application/x-www-form-urlencoded" --data "car.color=Red&car.brand=Ferrari" -X POST "$URL/cars"
>>>> curl -i --header "Accept: application/json" -H "Content-type: application/x-www-form-urlencoded" --data "car.color=Blue&car.brand=Skoda" -X POST "$URL/cars"
>>>> curl -i --header "Accept: application/json" -H "Content-type: application/x-www-form-urlencoded" --data "car.color=Green&car.brand=Audi" -X POST "$URL/cars"
>>>> curl -i --header "Accept: application/json" -H "Content-type: application/x-www-form-urlencoded" --data "car.color=Yello&car.brand=Opel" -X POST "$URL/cars"
>>>> curl -i --header "Accept: application/json" -H "Content-type: application/x-www-form-urlencoded" --data "car.color=Pink&car.brand=Mini" -X POST "$URL/cars"
>>>> curl -i --header "Accept: application/json" -H "Content-type: application/x-www-form-urlencoded" --data "car.color=Gray&car.brand=Nissan" -X POST "$URL/cars"
>>>> curl -i --header "Accept: application/json" -H "Content-type: application/x-www-form-urlencoded" --data "car.color=Red&car.brand=Volvo" -X POST "$URL/cars"
>>>> curl -i --header "Accept: application/json" -H "Content-type: application/x-www-form-urlencoded" --data "car.color=Blue&car.brand=Saab" -X POST "$URL/cars"
>>>> curl -i --header "Accept: application/json" -H "Content-type: application/x-www-form-urlencoded" --data "car.color=Black&car.brand=Mazda" -X POST "$URL/cars"
>>>> curl -i --header "Accept: application/json" -H "Content-type: application/x-www-form-urlencoded" --data "car.color=Yello&car.brand=Golf" -X POST "$URL/cars"
>>>>
>>>> The example uses an in-memory database so the data will be cleared upon
>>>> redployment/restart of the server. So you only need to populate/post when
>>>> you've restared or redployed.
>>>>
>>>> With the cars in place, we can now issue GET requests with paging query
>>>> parameters. The following route has been added to the demo:
>>>>
>>>> route()
>>>> .from("/cars")
>>>> .on(RequestMethod.GET)
>>>> .produces(MediaType.JSON.toString())
>>>> .to(Cars.class).get(param("page", "0"), param("perPage", "-1"));
>>>>
>>>> From this we can see that there are two optional parameters, page and
>>>> perPage. If these are not specified all cars will be returned.
>>>> Getting a page of Cars
>>>>
>>>> URL="http://controllerdemo-danbev.rhcloud.com/aerogear-controller-demo"
>>>> curl -i --header "Accept: application/json" "$URL/cars?page=0&perPage=4"
>>>>
>>>> The request will return:
>>>>
>>>> {
>>>> "metadata":{"page":0,"perPage":4},
>>>> "cars":[
>>>> {"color":"Black","brand":"BMW","id":1},
>>>> {"color":"Red","brand":"Ferrari","id":2},
>>>> {"color":"Blue","brand":"Skoda","id":3},
>>>> {"color":"Green","brand":"Audi","id":4}
>>>> ],
>>>> "links":{
>>>> "first":"cars?page=0&page=4",
>>>> "previous":"cars?page=0&page=4",
>>>> "next":"cars?page=1&page=4"
>>>> }}
>>>>
>>>> Getting the next page of Cars
>>>>
>>>> To get the next page you can follow the next link:
>>>>
>>>> URL="http://controllerdemo-danbev.rhcloud.com/aerogear-controller-demo"
>>>> curl -i --header "Accept: application/json" "$URL/cars?page=1&perPage=4"
>>>>
>>>> {
>>>> "metadata":{"page":1,"perPage":4},
>>>> "cars":[
>>>> {"color":"Yello","brand":"Opel","id":5},
>>>> {"color":"Pink","brand":"Mini","id":6},
>>>> {"color":"Gray","brand":"Nissan","id":7},
>>>> {"color":"Red","brand":"Volvo","id":8}
>>>> ],
>>>> "links":{
>>>> "first":"cars?page=0&page=4",
>>>> "previous":"cars?page=0&page=4",
>>>> "next":"cars?page=2&page=4"
>>>> }}
>>>>
>>>> Get all Cars
>>>>
>>>> URL="http://controllerdemo-danbev.rhcloud.com/aerogear-controller-demo"
>>>> curl -i --header "Accept: application/json" "$URL/cars"
>>>>
>>>> Get a single Car
>>>>
>>>> URL="http://controllerdemo-danbev.rhcloud.com/aerogear-controller-demo"
>>>> curl -i --header "Accept: application/json" "$URL/cars/1"
>>>>
>>>> The request will return:
>>>>
>>>> {"color":"Black","brand":"BMW","id":1}
>>>>
>>>>
>>>> Hmmm, the data returned should be consistent, right? Whether paging
>>>> parameters are supplied or not, the structure of the JSON to access the car
>>>> info should be the same. It's fine to leave out the metadata and links when
>>>> they're not needed I guess but to access the car info, currently you have:
>>>>
>>>> Not Paged: {"color":"Black","brand":"BMW","id":1}
>>>> Paged: {"cars":[{"color":"Black","brand":"BMW","id":1},…]}
>>>>
>>>> I know it's just a demo but I think making that JSON format consistent
>>>> so that the car data is always in an array under the "cars" key would be
>>>> better.
>>>>
>>>> Again, anything here can be changed, the name of the query parameters,
>>>> the implementation, and what is returned.
>>>>
>>>> Reference:
>>>>
>>>> - Paging Support in AeroGear Controller<https://gist.github.com/4147473>
>>>>
>>>> _______________________________________________
>>>> aerogear-dev mailing list
>>>> aerogear-dev at lists.jboss.org
>>>> https://lists.jboss.org/mailman/listinfo/aerogear-dev
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> aerogear-dev mailing list
>>>> aerogear-dev at lists.jboss.org
>>>> https://lists.jboss.org/mailman/listinfo/aerogear-dev
>>>>
>>>>
>>>
>>
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--
Viele Grüße/Best Regards
Daniel Manzke
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