I'm trying to set up a system with multiple applications connecting by use of a discovery server. I can traverse the hal responses to a specific resource, but I'm looking for a solution to get from a collection resource to a single resource and find the data for a specific entity.
In 1 application I have a RepositoryRestResource exposing some object:
#RestRepositoryResource(collectionResourceRel="things", itemResourceRel="thing") public interface ThingRepo extends CrudRepository<Thing,Long> {}
In some other application, I would like to get to a single thing. I have the id (let's say it's 1) and have the relation name of the collection and the single resource.
I would like to use a DiscoveredResource to get a link to this single item resource, or to the collection resource which I can then somehow expand using the ID (which would require a templated resource).
If at all possible I would not like to just add "/1" at the end of the URL.
this is how I currently create a DiscoveredResource to point to the collection resource:
new DiscoveredResource(new DynamicServiceInstanceProvider(discoveryClient, traverson -> traverson.follow("things"));
Should I and is it possible to add a templated link on a collection resource created by a #RepositoryRestResource. Or is there some other trick I am missing?
The solution here is to add a custom method as a #RestResource which exposes a relation with a templates URL you can then follow to.
Repo:
#RestRepositoryResource(collectionResourceRel="things", itemResourceRel="thing") public interface ThingRepo extends CrudRepository<Thing,Long> {
#RestResource(rel = "thing")
Thing findOneById(#Param("id") Long id);
}
Discovery + traverson:
DiscoveredResource resource = new DiscoveredResource(new DynamicServiceInstanceProvider(discoveryClient, traverson -> traverson.follow("things","search","thing"));
Link link = resource.getLink().expand(id);
Related
In my project I have lot of endpoint views (APIViews, ViewSets). For all of them now I set permissions, some of them are default (e.g. AllowAny) and some are custom created:
permission_classes = (IsUserHaveSomePermission,)
Now I want to implement some flexible system, that will allow me to specify set of allowed endpoints for each user, for example:
On front-end I want to select some user and have a list of checkboxes that correspond to project's endpoints.
This is just an utopian solution, some details may be changed, but the main question is to how make something similar so that admins can basically dynamically change list of allowed endpoints/views for user?
thanks in advance
This solution can be implemented by storing if the user has permission to access the current request method and request path.
Create a new db model for storing the user, request method and request path. Lets say the name of the model is RequestPermission
Instead of the path you can store a constant representing the url so that you have the flexibility of editing the path later on. This constant can be the url name which is supported by django.
class RequestPermission(models.Model):
user = user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='request_permissions')
method = models.CharField(max_length=10)
path_name = models.CharField(max_length=200)
create a custom permission class:
class IsUserResuestAllowed(permissions.BasePermission):
def has_permission(self, request, view):
user = request.user
# you can choose how to get the path_name from the path
path_name = get_path_name(request.path)
return RequestPermission.objects.filter(user=user, method=request.method, path_name=path_name).exists()
Now you can use this class as the default permission class in rest framework settings or use it per view.
Is there anyway that I can generate some metadata to add to the service when it registers.
We are moving from Eureka to Consul and I need to add a UUID value to the registered metadata when a service starts. So that later I can get this metadata value when I retrieve the service instances by name.
Some background: We were using this excellent front end UI from https://github.com/VanRoy/spring-cloud-dashboard. It is set to use the Eureka model for services in which you have an Application with a name. Each application will have multiple instances each with an instance id.
So with the eureka model there is a 2 level service description whereas the spring cloud model is a flat one where n instances each of which have a service id.
The flat model won't work with the UI that I referenced above since there is no distinction between application name and instance id which is the spring model these are the same.
So if I generate my own instance id and handle it through metadata then I can preserve some of the behaviour without rewriting the ui.
See the documentation on metadata and tags in spring cloud consul. Consul doesn't support metadata on service discovery yet, but spring cloud has a metadata abstraction (just a map of strings). In consul tags created with key=value style are parsed into that metadata map.
For example in, application.yml:
spring:
cloud:
consul:
discovery:
tags: foo=bar, baz
The above configuration will result in a map with foo→bar and baz→baz.
Based on Spencer's answer I added an EnvironmentPostProcessor to my code.
It works and I am able to add the metadata tag I want programmatically but it is a complement to the "tags: foo=bar, baz" element so it overrides that one. I will probably figure a way around it in the next day or so but I thougth I would add what I did for other who look at this answer and say, so what did you do?
first add a class as follows:
#Slf4j
public class MetaDataEnvProcessor implements EnvironmentPostProcessor, Ordered {
// Before ConfigFileApplicationListener
private int order = ConfigFileApplicationListener.DEFAULT_ORDER - 1;
private UUID instanceId = UUID.randomUUID();
#Override
public int getOrder() {
return this.order;
}
#Override
public void postProcessEnvironment(ConfigurableEnvironment environment,
SpringApplication application) {
LinkedHashMap<String, Object> map = new LinkedHashMap<>();
map.put("spring.cloud.consul.discovery.tags", "instanceId="+instanceId.toString());
MapPropertySource propertySource = new MapPropertySource("springCloudConsulTags", map);
environment.getPropertySources().addLast(propertySource);
}
}
then add a spring.factories in resources/META-INF with eht following line to add this processor
org.springframework.boot.env.EnvironmentPostProcessor=com.example.consul.MetaDataEnvProcessor
This works fine except for the override of what is in your application.yml file for tags
I am struggling with a design aspect of my restful api for templating collections of resources.
The endpoint calls for a json with the name to a particular template and a collections of tokens. The API will then create entries into numerous tables and use the tokens where appropriate.
A very simple example is:
*{
'template': 'DeviceTemplate'
'tokens': [
'customer': 1234,
'serial_number': '12312RF3242a',
'ip_address': '1.1.1.1'
]
}*
This creates a new device for the customer with that ip address along with several other objects, for instance interfaces, device users etc etc. I use the tokens in various places where needed.
I'm not sure how to make this endpoint restful.
The endpoint for /device is already taken if you want to create this resource individually. The endpoint I need is for creating everything via the template.
I want to reserve the POST /template endpoint for creating the actual template itself and not for implementing it with the tokens to create the various objects.
I want to know how to call the endpoint without using a verbs.
I also want to know if its a good idea to structure a POST with a nested JSON.
I'd suggest that you create an action on the template object itself. So right now if you do /templates/<id> you are given an object. You should include in that object a url endpoint for instantiating an instance of that template. Github follows a scheme that I like a lot [1] where within an object there will be a key pointing to another url with a suffix _url. So for instance, your response could be something like:
{
"template": "DeviceTemplate",
"id": "127",
...
"create_url": "https://yourdomain.com/templates/127/create",
...
}
Then this way you treat a POST to that endpoint the same as if this template (DeviceTemplate) was its own resource.
The way to conceptualize this is you're calling a method on an object instead of calling a function.
[1] - For example https://developer.github.com/v3/#failed-login-limit
I am making a web crawler using Groovy on Grails and MongoDB at the backend. I am unsure of how to model the domain class for the same.
Ex:
Domain Class Website contains websites that user has presaved and wants to crawl.
Model website contains : www.google.com
After Crawling www.google.com I get following information:
www.a.com resource types other metrics
www.b.com resource types other metrics
www.c.com resource types other metrics
www.d.com resource types other metrics
I want to store them in database and continue crawling. Again, www.a.com when crawled will yield more urls like :
www.a1.com resource types other metrics
www.a2.com resource types other metrics
Similarly for all other urls, they would have child URLs. How can I model a domain class for it? One idea that I have is have a domain class(that will have an association with itself) as follows but I am not sure if its the right approach:
class Resource implements Comparable {
String url
String otherMetrics
SortedSet subResources
static hasMany = [subResources: Resource]
static belongsTo = [parent: Resource]
}
I think your code doesn't work because you forget the mappedBy part:
You'll probably need the next line to get it work:
static mappedBy = [subResources:'parent']
At the end, it is a tree, and I use the same approach for this kind of problem.
Hope this helps.
I'm upgrading a custom solution where I can dynamically register and unregister Web Api controllers to use the new attribute routing mechanism. However, it seems to recent update to RTM break my solution.
My solution exposes a couple of Web Api controllers for administration purposes. These are registered using the new HttpConfigurationExtensions.MapHttpAttributeRoutes method call.
The solution also allows Web Api controllers to be hosted in third-party assemblies and registered dynamically. At this stage, calling HttpConfigurationExtensions.MapHttAttributeRoutes a second time once the third-party controller is loaded would raise an exception. Therefore, my solution uses reflection to inspect the RoutePrefix and Route attributes and register corresponding routes on the HttpConfiguration object.
Unfortunately, calling the Web Api results in the following error:
"No HTTP resource was found that matches the request URI".
Here is a simple controller that I want to use:
[RoutePrefix("api/ze")]
public sealed class ZeController : ApiController
{
[HttpGet]
[Route("one")]
public string GetOne()
{
return "One";
}
[HttpGet]
[Route("two")]
public string GetTwo()
{
return "Two";
}
[HttpPost]
[Route("one")]
public string SetOne(string value)
{
return String.Empty;
}
}
Here is the first solution I tried:
configuration.Routes.MapHttpRoute("ZeApi", "api/ze/{action}");
Here is the second solution I tried:
var type = typeof(ZeController);
var routeMembers = type.GetMethods().Where(m => m.IsPublic);
foreach (MethodInfo method in routeMembers)
{
var routeAttribute = method.GetCustomAttributes(false).OfType<RouteAttribute>().FirstOrDefault();
if (routeAttribute != null)
{
string controllerName = type.Name.Substring(0, type.Name.LastIndexOf("Controller"));
string routeTemplate = string.Join("/", "api/Ze", routeAttribute.Template);
configuration.Routes.MapHttpRoute(method.Name, routeTemplate);
}
}
I also have tried a third solution, whereby I create custom classes that implement IHttpRoute and trying to register them with the configuration to no avail.
Is it possible to use legacy-style route mapping based upon the information contained in the new routing attributes ?
Update
I have installed my controller in a Web Application in order to troubleshoot the routing selection process with the Web Api Route Debugger. Here is the result of the screenshot:
As you can see, the correct action seems to be selected, but I still get a 404 error.
Update2
After further analysis, and per Kiran Challa's comment below, it seems that the design of Web Api prevents mixing attribute routing and conventional routing, and that what I want to do is not possible using this approach.
I have created a custom attribute [RouteEx] that serves the same purpose of the Web Api [Route] attribute, and now my code works perfectly.
I guess, since this is not possible using the conventional attribute routing, none of the answers on this question could legitimately be consisered valid. So I'm not nominating an answer just yet.
You shouldn't be required to use reflection and inspect the attribute-routing based attributes yourself. Attribute routing uses existing Web API features to get list of controllers to scan through.
Question: Before the switch to attribute routing, how were you loading these assemblies having the
controllers?
If you were doing this by IAssembliesResolver service, then this solution should work even with attribute routing and you should not be needing to do anything extra.
Regarding your Update: are you calling MapHttpAttributeRoutes?