Is there a way to reconfigure the Grails 3 Link Generator to create Restful links, i.e. localhost:8080/book/{id} rather than the old style that includes the action in the URL, localhost:8080/book/show/{id}?
I'd like to have restful URLs in the location headers of the responses to save actions.
I've been using this Grails Restful Link Generator as a workaround. I'm not perfectly happy with it, but it's the best I've been able to come up with thus far.
1. Create a trait in src/main/groovy that removes the superfluous action from the URL
import grails.web.mapping.LinkGenerator
trait RestfulLinkGeneratorTrait {
LinkGenerator grailsLinkGenerator
String generateLink(Map map) {
map.controller = map.controller ?: this.controllerName
map.absolute = map.absolute ?: true
map.action = map.action ?: "show"
grailsLinkGenerator.link(map).replace("/$map.action", "")
}
}
2. Implement the RestfulLinkGenerator on your controller(s) and call generateLink(id: obj.id) to generate links.
#Secured('ROLE_USER')
class BookController extends RestfulController implements RestfulLinkGeneratorTrait {
//... other methods ...//
#Transactional
def save() {
// ... save you resource ... //
response.addHeader(HttpHeaders.LOCATION, generateLink(id: book.id))
respond book, [status: CREATED, view: 'show']
}
//... other methods ...//
}
Related
I am using ASP.NET Web API. I want to REST uri to be
GET /api/v1/documents/1234/download or
GET /api/v1/documents/1234?act=download or
GET /api/v1/documents?id=1234&act=download
Is it possible to have multiple ways to call REST API Url? Is it recommended?
I am using Attribute Routes only
[RoutePrefix("api/v1")]
public class DocumentController : ApiController
{
private readonly DomainService _domainService;
public DocumentController(DomainService domainService)
: base(domainService)
{
_domainService = domainService ?? throw new ArgumentNullException(nameof(domainService));
}
[HttpGet]
[Route("documents/{id:int}")]
public async Task<IHttpActionResult> DownloadDocument([FromUri]int id, [FromUri]string act)
{
if (string.IsNullOrEmpty(act) || act.ToUpper() != "DOWNLOAD")
{
return BadRequest("Invalid action parameter.");
}
return await service.DownloadFile(id);
}
}
with above code only GET /api/v1/documents/1234?act=download works. Is it possible to configure route in a such way that all 3 routes will invoke same action method?
You can add as many Route attributes as required to each method.
So you could do this to your method:
[Route("documents")] // matches /documents?id=123&act=download
[Route("documents/{id:int}")] // matches /documents/123?act=download
[Route("documents/{id:int}/{act}")] // matches /documents/123/download
Personally I think this is quite long-winded, and would try to stick to a single style (the last one if I could choose), but I guess it could depend on your requirements.
I would like to design a client that would talk to a REST API. I have implemented the bit that actually does call the HTTP methods on the server. I call this Layer, the API layer. Each operation the server exposes is encapsulated as one method in this layer. This method takes as input a ClientContext which contains all the needed information to make the HTTP method call on the server.
I'm now trying to set up the interface to this layer, let's call it ClientLayer. This interface will be the one any users of my client library should use to consume the services. When calling the interface, the user should create the ClientContext, set up the request parameters depending on the operation that he is willing to invoke. With the traditional Java approach, I would have a state on my ClientLayer object which represents the ClientContext:
For example:
public class ClientLayer {
private static final ClientContext;
...
}
I would then have some constructors that would set up my ClientContext. A sample call would look like below:
ClientLayer client = ClientLayer.getDefaultClient();
client.executeMyMethod(client.getClientContext, new MyMethodParameters(...))
Coming to Scala, any suggestions on how to have the same level of simplicity with respect to the ClientContext instantiation while avoiding having it as a state on the ClientLayer?
I would use factory pattern here:
object RestClient {
class ClientContext
class MyMethodParameters
trait Client {
def operation1(params: MyMethodParameters)
}
class MyClient(val context: ClientContext) extends Client {
def operation1(params: MyMethodParameters) = {
// do something here based on the context
}
}
object ClientFactory {
val defaultContext: ClientContext = // set it up here;
def build(context: ClientContext): Client = {
// builder logic here
// object caching can be used to avoid instantiation of duplicate objects
context match {
case _ => new MyClient(context)
}
}
def getDefaultClient = build(defaultContext)
}
def main(args: Array[String]) {
val client = ClientFactory.getDefaultClient
client.operation1(new MyMethodParameters())
}
}
When following http://grails.org/doc/latest/guide/webServices.html#restfulControllers in order to create RESTful webservices, I am getting 404 error when I hit anything other than index.
in my Bootstrap.groovy I have
def init = { servletContext ->
new Restaurant(title:"mourne seafood").save()
new Restaurant(title:"RBG").save()
}
in my Restaurant.groovy domain class i have
class Restaurant {
String title
static constraints = {
}
}
and in my RestaurantController.groovy REST controller I have
import grails.rest.*;
class RestaurantController extends RestfulController {
static responseFormats = ['json', 'xml']
RestaurantController() {
super(Restaurant)
}
}
I thought when reading the above link that if I call
GET <domain>/restaurant
It would call the index method, which is fine, this works, however when I call
GET <domain>/restaurant/1
I thought it should call the show method with 1 as the id? However I am getting a 404. It works correctly when I hit GET <domain>/restaurant/show/2 am I wrong in thinking that when the docs say
GET /books/${id} show in the mapping table that I shouldnt have to explicitly put show in the URL?
I know It sucks but here it is:
You need to create a generic rest controller and annotate the domain class pointing to it.
First delete the RestaurantController.groovy
Then create a BaseRestController (inside the src/main/groovy folder)
src/main/groovy/BaseRestController.groovy
import grails.rest.*;
class BaseRestController<T> extends RestfulController<T> {
BaseRestController(Class<T> domainClass) {
this(domainClass, false)
}
BaseRestController(Class<T> domainClass, boolean readOnly) {
super(domainClass, readOnly)
}
#Override
def show() {
println 'showing...'
respond queryForResource(params.id)
}
}
Ps. I just override the index action to show it works
Now you can annotate the domain class
grails-app/domain/Restaurant.groovy
import grails.rest.*
#Resource(uri='/restaurants', formats=['json', 'xml'], superClass=BaseRestController)
class Restaurant {
String title
static constraints = {
}
}
You need to specify the formats in the domain class and not in the controller. Otherwise it will be ignored and XML will be default.
I named the api endpoint as restaurants instead of the grails default restaurant
Now you can HTTP your RestFull app e.g. http://localhost:8080/restaurants/1
What’s the preferred way to handle 404 errors with Play 2.0 and show a nice templated view?
You can override the onHandlerNotFound method on your Global object, e.g.:
object Global extends GlobalSettings {
override def onHandlerNotFound(request: RequestHeader): Result = {
NotFound(views.html.notFound(request))
}
}
Please note that there are really two different problems to solve:
Showing a custom 404 page when there is "no handler found", e.g. when the user goes to an invalid URL, and
Showing a custom 404 (NotFound) page as a valid outcome of an existing handler.
I think the OP was referring to #2 but answers referred to #1.
"No Handler Found" Scenario
In the first scenario, for "no handler found" (i.e. invalid URL), the other answers have it right but to be more detailed, per the Play 2.1 documentation as:
Step 1: add a custom Global object:
import play.api._
import play.api.mvc._
import play.api.mvc.Results._
object Global extends GlobalSettings {
override def onHandlerNotFound(request: RequestHeader): Result = {
NotFound(
views.html.notFoundPage(request.path)
)
}
}
Step 2: add the template. Here's mine:
#(path: String)
<html>
<body>
<h1>Uh-oh. That wasn't found.</h1>
<p>#path</p>
</body>
</html>
Step 3: tweak your conf/application.conf to refer to your new "Global". I put it in the controllers package but it doesn't have to be:
...
application.global=controllers.Global
Step 4: restart and go to an invalid URL.
"Real Handler can't find object" Scenario
In the second scenario an existing handler wants to show a custom 404. For example, the user asked for object "1234" but no such object exists. The good news is that doing this is deceptively easy:
Instead of Ok(), surround your response with NotFound()
For example:
object FruitController extends Controller {
def showFruit(uuidString: String) = Action {
Fruits.find(uuidString) match {
case Some(fruit) => Ok(views.html.showFruit(fruit))
// NOTE THE USE OF "NotFound" BELOW!
case None => NotFound(views.html.noSuchFruit(s"No such fruit: $uuidString"))
}
}
}
What I like about this is the clean separation of the status code (200 vs 404) from the HTML returned (showFruit vs noSuchFruit).
HTH
Andrew
If you want to do the same using Java instead of Scala you can do it in this way (this works for play framework 2.0.3):
Global.java:
import play.GlobalSettings;
import play.mvc.Result;
import play.mvc.Results;
import play.mvc.Http.RequestHeader;
public class Global extends GlobalSettings {
#Override
public Result onHandlerNotFound(RequestHeader request) {
return Results.notFound(views.html.error404.render());
}
}
Asumming that your 404 error template is views.html.error404 (i.e. views/error404.scala.html).
Please note that Play development team are making lots of efforts to move away from global state in Play, and hence GlobalSettings and the application Global object have been deprecated since version 2.4.
HttpErrorHandler.onClientError should be used instead of
GlobalSettings.onHandlerNotFound. Basically create a class that inherits from HttpErrorHandler, and provide an implementation for onClientError method.
In order to find out type of error (404 in your case) you need to read status code, which is passed as a one of the method arguments e.g.
if(statusCode == play.mvc.Http.Status.NOT_FOUND) {
// your code to handle 'page not found' situation
// e.g. return custom implementation of 404 page
}
In order to let Play know what handler to use, you can place your error handler in the root package or configure it in application.conf using play.http.errorHandler configuration key e.g.
play.http.errorHandler = "my.library.MyErrorHandler"
You can find more details on handling errors here: for Scala or Java.
This works in 2.2.1. In Global.java:
public Promise<SimpleResult> onHandlerNotFound(RequestHeader request) {
return Promise.<SimpleResult>pure(notFound(
views.html.throw404.render()
));
}
Ensure that you have a view called /views/throw404.scala.html
This works in 2.2.3 Play - Java
public Promise<SimpleResult> onHandlerNotFound(RequestHeader request) {
return Promise<SimpleResult>pure(Results.notFound(views.html.notFound404.render()));
}
html should be within /views/notFound404.scala.html
Dont forget to add Results.notFounf() and import play.mvc.Results;
For Java, if you want to just redirect to main page, I solved it by this.
#Override
public Promise<Result> onHandlerNotFound(RequestHeader request) {
return Promise.pure(redirect("/"));
}
This is more like a conceptual question. When to use Model Binding (in ASP.NET MVC Framework) and when to inject objects using IoC (lets say Autofac here) ?
One specific scenario is like lets say, I have the following action method
public ActionResult EditProfile(string UserId)
{
// get user object from repository using the the UserId
// edit profile
// save changes
// return feedback
}
In the above scenario, is it possible to inject a user object to action method such that it automatically gets the user object using the UserId ? The resulting signature being:
public ActionResult EditProfile(UserProfile userObj) //userObj injected *somehow* to automatically retreive the object from repo using UserId ?
Sorry if it all doesn't makes sense. It`s my first time using IoC.
EDIT:
This is the way to do it > http://buildstarted.com/2010/09/12/custom-model-binders-in-mvc-3-with-imodelbinder/
You can do what you need using a custom action filter. By overriding OnActionExecuting, we have access to the route data, and the action parameters of the action that will be executed. Given:
public class BindUserProfileAttribute : ActionFilterAttribute
{
public override OnActionExecuting(FilterContext filterContext)
{
string id = (string)filterContext.RouteData.Values["UserId"];
var model = new UserProfile { Id = id };
filtextContext.ActionParameters["userObj"] = model;
}
}
This attribute allows us to create the parameters that will be passed into the action, so we can load the user object at this point.
[BindUserProfile]
public ActionResult EditProfile(UserProfile userObj)
{
}
You'll probably need to get specific with your routes:
routes.MapRoute(
"EditProfile",
"Account/EditProfile/{UserId}",
new { controller = "Account", action = "EditProfile" });
In MVC3 we get access to the new IDepedencyResolver interface, which allows us to perform IoC/SL using whatever IoC container or service locator we want, so we can push a service like a IUserProfileFactory into your filter, to then be able to create your UserProfile instance.
Hope that helps?
Model binding is used for your data. Dependency injection is used for your business logic.