I have a simple use case where I would like to consume a resource collection that is represented with json+hal.
I use the spring RestTemplate and have configuired it to use the Jackson2HalModule.
When I debug my code I find that the Response object does contain accurate metadata (e.g. number of pages and resources) and response headers but there is no content or links. I have looked at many articles and guides on the internet over the last day, and I feel that my custom rest template should be working for my use case based on my findings.
If anybody can shed any light on this I would be eternally grateful.
My code for my service is as follows:
#Service
public class EventServiceImpl extends BaseService implements EventService {
private static final String knownEntity = "59d786d642572853721728f6";
private static String SERVICE_URL = "http://EVENTS-SERVER";
private static String EVENTS_PATH = "/events";
#Autowired
#LoadBalanced
protected RestTemplate restTemplate;
#Override
public ResponseEntity<PagedResources<Event>> fetchEventsList() {
// acceptable media type
List<MediaType> acceptableMediaTypes = Arrays.asList(HAL_JSON);
// header
HttpHeaders headers = new HttpHeaders();
headers.setAccept(acceptableMediaTypes);
HttpEntity<String> entity = new HttpEntity<String>(null, headers);
ResponseEntity<PagedResources<Event>> response = getRestTemplateWithHalMessageConverter()
.exchange(SERVICE_URL + EVENTS_PATH, HttpMethod.GET, entity, new ParameterizedTypeReference<PagedResources<Event>>(){});
return response;
}
public RestTemplate getRestTemplateWithHalMessageConverter() {
List<HttpMessageConverter<?>> existingConverters = restTemplate.getMessageConverters();
List<HttpMessageConverter<?>> newConverters = new ArrayList<>();
newConverters.add(getHalMessageConverter());
newConverters.addAll(existingConverters);
restTemplate.setMessageConverters(newConverters);
return restTemplate;
}
private HttpMessageConverter getHalMessageConverter() {
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.registerModule(new Jackson2HalModule());
MappingJackson2HttpMessageConverter halConverter = new TypeConstrainedMappingJackson2HttpMessageConverter(ResourceSupport.class);
objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
halConverter.setSupportedMediaTypes(Arrays.asList(HAL_JSON));
halConverter.setObjectMapper(objectMapper);
return halConverter;
}
And my simple model is:
public class Event {
private String name;
private String location;
private int capacity;
public String getName() {
return name;
}
public String getLocation() {
return location;
}
public int getCapacity() {
return capacity;
}
}
For completeness, here is a samle of the shape of the hal+json I am attempting to consume:
{
"_embedded": {
"events": [
{
"name": null,
"location": null,
"capacity": 0,
"currentState": "CANCELLED",
"_links": {
"self": {
"href": "http://192.168.1.6:2221/events/59d786d642572853721728f6"
},
"event": {
"href": "http://192.168.1.6:2221/events/59d786d642572853721728f6"
},
"reinstate": {
"href": "http://192.168.1.6:2221/events/59d786d642572853721728f6/reinstate"
},
"reschedule": {
"href": "http://192.168.1.6:2221/events/59d786d642572853721728f6/reschedule"
}
}
},
{
"name": null,
"location": null,
"capacity": 0,
"currentState": "ADVERTISED",
"_links": {
"self": {
"href": "http://192.168.1.6:2221/events/59d7f14342572812ceca7fc6"
},
"event": {
"href": "http://192.168.1.6:2221/events/59d7f14342572812ceca7fc6"
},
"cancel": {
"href": "http://192.168.1.6:2221/events/59d7f14342572812ceca7fc6/cancel"
},
"reschedule": {
"href": "http://192.168.1.6:2221/events/59d7f14342572812ceca7fc6/reschedule"
}
}
},
{
"name": null,
"location": null,
"capacity": 0,
"currentState": "ADVERTISED",
"_links": {
"self": {
"href": "http://192.168.1.6:2221/events/59d7f14742572812ceca7fc7"
},
"event": {
"href": "http://192.168.1.6:2221/events/59d7f14742572812ceca7fc7"
},
"cancel": {
"href": "http://192.168.1.6:2221/events/59d7f14742572812ceca7fc7/cancel"
},
"reschedule": {
"href": "http://192.168.1.6:2221/events/59d7f14742572812ceca7fc7/reschedule"
}
}
},
{
"name": null,
"location": null,
"capacity": 0,
"currentState": "ADVERTISED",
"_links": {
"self": {
"href": "http://192.168.1.6:2221/events/59d7f14c42572812ceca7fc8"
},
"event": {
"href": "http://192.168.1.6:2221/events/59d7f14c42572812ceca7fc8"
},
"cancel": {
"href": "http://192.168.1.6:2221/events/59d7f14c42572812ceca7fc8/cancel"
},
"reschedule": {
"href": "http://192.168.1.6:2221/events/59d7f14c42572812ceca7fc8/reschedule"
}
}
}
]
},
"_links": {
"self": {
"href": "http://192.168.1.6:2221/events{?page,size,sort}",
"templated": true
},
"profile": {
"href": "http://192.168.1.6:2221/profile/events"
}
},
"page": {
"size": 20,
"totalElements": 4,
"totalPages": 1,
"number": 0
}
}
EDIT: I can consume an individual Event with no problems.
I had a similar problem and I ended up using org.springframework.hateoas.Resources
For my example below, this object is located in org.springframework.hateoas:spring-hateoas:jar:0.25.2.RELEASE
which is being pulled in from org.springframework.boot:spring-boot-starter-data-rest:jar:2.1.7.RELEASE, so there's a good chance its already in your classpath assuming you declare the spring-boot-starter-data-rest dependency.
Here's a simple example (using your info):
RestTemplate restTemplate = new RestTemplate();
Resources<Event> resourceEvents = restTemplate.getForObject("http://192.168.1.6:2221/events", Resources.class);
List<Event> events = new ArrayList<>(resourceEvents.getContent());
There are probably some gotchas the make this not so straight forward, but hopefully this provides a start to solving your problem.
Related
I am looking to generate an api that take different content type.
The problem I am facing is that if I run several time my application I have different output documentation
#RestController
public class MyRestController {
#Operation(summary = "GetMyData", operationId = "gettt",
responses = #ApiResponse(responseCode = "204", content = #Content(mediaType = "application/vnd.something")))
#GetMapping(produces = "application/vnd.something")
public ResponseEntity<Void> getSomethingElse() {
return noContent().build();
}
#GetMapping(produces = TEXT_PLAIN_VALUE)
public String get() {
return "some text";
}
#GetMapping(produces = HAL_JSON_VALUE)
public EntityModel<JsonResponse> getHal() {
return EntityModel.of(new JsonResponse(),
linkTo(MyRestController.class).slash("somelink").withSelfRel()
);
}
#GetMapping(produces = APPLICATION_JSON_VALUE)
public JsonResponse getJson() {
return new JsonResponse();
}
}
It currently generate a wrong api-docs
"operationId": "gettt_1_1_1",
"responses": {
"200": {
"content": {
"application/hal+json": {
"schema": {
"$ref": "#/components/schemas/EntityModelJsonResponse"
}
},
"application/json": {
"schema": {
"$ref": "#/components/schemas/JsonResponse"
}
},
"text/plain": {
"schema": {
"type": "string"
}
}
},
"description": "OK"
},
"204": {
"content": {
"application/hal+json": {
"schema": {
"$ref": "#/components/schemas/EntityModelJsonResponse"
}
},
"application/vnd.something": {},
"text/plain": {
"schema": {
"type": "string"
}
}
},
"description": "No Content"
}
},
If I restart my server without changing the code the following response is generated
"operationId": "gettt_1",
"responses": {
"200": {
"content": {
"application/hal+json": {
"schema": {
"$ref": "#/components/schemas/EntityModelJsonResponse"
}
},
"application/json": {
"schema": {
"$ref": "#/components/schemas/JsonResponse"
}
},
"text/plain": {
"schema": {
"type": "string"
}
}
},
"description": "OK"
},
"204": {
"content": {
"application/vnd.something": {}
},
"description": "No Content"
}
},
I would expect that restarting my server will always generate the same documentation
Have you looked at the documentation?
https://springdoc.github.io/springdoc-openapi-demos/springdoc-properties.html#swagger-ui-properties
You can use the swagger-ui properties, without having to override the standard way of sorting (operationsSorter and tagsSorter).
For example:
springdoc.swagger-ui.operationsSorter=method
springdoc.swagger-ui.tagsSorter=alpha
If you want a an order on the server side, you can use OpenApiCustomiser, to sort the elements
This is a sample code that you can customize using Comparators, depending on the sorting logic you want:
Example, for alphabetical order sorting of schemas:
#Bean
public OpenApiCustomiser sortSchemasAlphabetically() {
return openApi -> {
Map<String, Schema> schemas = openApi.getComponents().getSchemas();
openApi.getComponents().setSchemas(new TreeMap<>(schemas));
};
}
Example for sorting tags, in alphabetical order:
#Bean
public OpenApiCustomiser sortTagsAlphabetically() {
return openApi -> openApi.setTags(openApi.getTags()
.stream()
.sorted(Comparator.comparing(tag -> StringUtils.stripAccents(tag.getName())))
.collect(Collectors.toList()));
}
You can have full control on the elements order, and you can sort them depending on your use case...
one other flag mentioned here:
springdoc:
writer-with-order-by-keys
I am trying to write a Java program to consume the output from a REST-based web service I wrote utilizing the tutorials at spring.io. When I run SpringBoot bootRun the JSON output is built nicely with embedded data and links, and looks like this:
{
"_embedded": {
"invoiceList": [
{
"id": 4,
"seqNum": 1,
"fileId": null,
"fileName": null,
"invoiceNumber": "10080",
"invoiceDate": "2018-06-18T05:00:00.000+0000",
"invoiceTotal": 1000,
"sourceLastModified": "2018-11-30T16:22:23.000+0000",
"lastModified": "2018-11-30T16:22:23.000+0000",
"validFrom": "2018-11-30T16:22:23.000+0000",
"validTo": "9999-12-31T06:00:00.000+0000",
"_links": {
"self": {
"href": "http://localhost:8086/vadir/dental/invoices/4"
},
"invoices": {
"href": "http://localhost:8086/vadir/dental/invoices"
},
"claims": {
"href": "http://localhost:8086/vadir/dental/claims?invoice=10080"
}
}
},
{
"id": 5,
"seqNum": 1,
"fileId": null,
"fileName": null,
"invoiceNumber": "10080",
"invoiceDate": "2018-06-18T05:00:00.000+0000",
"invoiceTotal": 500,
"sourceLastModified": "2018-11-30T16:22:23.000+0000",
"lastModified": "2018-11-30T16:22:23.000+0000",
"validFrom": "2018-11-30T16:22:23.000+0000",
"validTo": "9999-12-31T06:00:00.000+0000",
"_links": {
"self": {
"href": "http://localhost:8086/vadir/dental/invoices/5"
},
"invoices": {
"href": "http://localhost:8086/vadir/dental/invoices"
},
"claims": {
"href": "http://localhost:8086/vadir/dental/claims?invoice=10080"
}
}
}
]
},
"_links": {
"self": {
"href": "http://localhost:8086/vadir/dental/invoices/last"
}
}
}
I have found the documentation for Traverson and the SO question at Consuming HAL-based REST. However, when I use
ParameterizedTypeReference<Resources<Resource<DentalInvoice>>> parameterizedTypeReference =
new ParameterizedTypeReference<Resources<Resource<DentalInvoice>>> () {
};
Traverson traverson =
new Traverson (new URI ("http://localhost:8086/vadir/dental/invoices/last"), MediaTypes.HAL_JSON);
Resources<Resource<DentalInvoice>> invoiceResources = traverson
//.follow ((String) null)
.follow ("$._embedded.invoiceList")
.toObject (parameterizedTypeReference);
I get an error: Illegal character in scheme name at index 0: [{"id":4,...
It looks like Traverson is expecting the content of the follow reference to be a link rather than an embedded object. How can I get Traverson to parse the embedded object into a list of Resources of DentalInvoices?
Do I have to create a controller method that only outputs the links to the possible actions just so Traverson has a link to follow?
to add my links in the Json frame of a projection I added the following class:
#Component
public class ResumeEntityProjectionResourceProcessor implements ResourceProcessor<Resource<ResumeEntity>> {
#Override
public Resource<ResumeEntity> process(Resource<ResumeEntity> resource) {
UriComponents uriComponents = ServletUriComponentsBuilder.fromCurrentContextPath()
.path("/api/entities/search/findEntities")
.buildAndExpand(Long.toString(resource.getContent().getId()));
resource.add(new Link(uriComponents.toUriString(), "findEntities"));
return resource;
}
The problem I had now as a return value was two keys "_links" one with the default links plus my links and the other with my links only.
{
"_embedded": {
"entities": [{
"id": 1696,
"reference": "aaaaaa",
"_links": {
"self": {
"href": "http://localhost:8080/myProject/api/entities/1696{?projection}",
"templated": true
},
"findByParametresValide": {
"href": "http://localhost:8080/myProject/api/entities/search/findEntities"
}
},
"_links": {
"findByParametresValide": {
"href": "http://localhost:8080/myProject/api/entities/search/findEntities"
}
}
}
]
}
}
How I did to keep only the first tag?
the expected result
{
"_embedded": {
"entities": [{
"id": 1696,
"reference": "aaaaaa",
"_links": {
"self": {
"href": "http://localhost:8080/myProject/api/entities/1696{?projection}",
"templated": true
},
"findByParametresValide": {
"href": "http://localhost:8080/myProject/api/entities/search/findEntities"
}
}
}
]
}
}
thanks
#Override
public Resource<ResumeEntity> process(Resource<ResumeEntity> resource) {
if (resource.getLinks().isEmpty()) {
return resource;
}
UriComponents uriComponents = ServletUriComponentsBuilder.fromCurrentContextPath()
.path("/api/entities/search/findEntities")
.buildAndExpand(Long.toString(resource.getContent().getId()));
resource.add(new Link(uriComponents.toUriString(), "findEntities"));
return resource;
}
"_embedded": {
"employees": [
{
"id": "1",
"name": "Some Employee",
"_links": {
"self": {
"href": "http://localhost:8080/employees/1"
}
}
},
{
"id": "2",
"name": "Some Employee",
"_links": {
"self": {
"href": "http://localhost:8080/employees/2"
}
}
},
{
"id": "3",
"name": "Some Employee",
"_links": {
"self": {
"href": "http://localhost:8080/employees/3"
}
}
}
]
},
{
"_links": {
"self": {
"href": "http://localhost:8080/employees{?page,size,sort}"
},
"search": {
"href": "http://localhost:8080/employees/search"
}
},
"page": {
"size": 20,
"totalElements": 3,
"totalPages": 1,
"number": 0
}
}
I'm reading a third-party Rest service that returns json content with the above structure or similar (content-type is application/json).
Currently, I created a custom json converter to a generic object that has custom objects for links,pages and a generic type for the embedded object. So that, I read it in some sort of generic way. However, I would like to do it via hateoas objects. I tried several approaches but any of them are working.
Following others questions I tried many things like configuring the RestTamplate
#Bean
public OAuth2RestTemplate getOAuth2Rest() {
[...]
OAuth2RestTemplate template = new OAuth2RestTemplate(resourceDetails, clientContext);
List<HttpMessageConverter<?>> existingConverters = template.getMessageConverters();
List<HttpMessageConverter<?>> newConverters = new ArrayList<>();
newConverters.add(getHalMessageConverter());
newConverters.addAll(existingConverters);
template.setMessageConverters(newConverters);
return template;
}
private HttpMessageConverter getHalMessageConverter() {
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
objectMapper.registerModule(new Jackson2HalModule());
MappingJackson2HttpMessageConverter halConverter =
new TypeConstrainedMappingJackson2HttpMessageConverter(ResourceSupport.class);
halConverter.setSupportedMediaTypes(Arrays.asList(HAL_JSON));
halConverter.setObjectMapper(objectMapper);
return halConverter;
}
Then
ResponseEntity<Resources<MyDto>> entity = restTemplate.exchange(
myUri,
HttpMethod.GET, null,
new ParameterizedTypeReference<Resources<MyDto>>() {}, Collections.emptyMap());
There are similar questions like Consuming Spring Hateoas Pageable but they are consuming json+hal content. I think here is my problem because the deserializer uses the json converter and not the hal converter.
I tried
#EnableHypermediaSupport(type = EnableHypermediaSupport.HypermediaType.HAL)
Didn't work and interferes with my REST configuration.
I tried this blog
We are trying to parse the below JSON to get a list of people.
JSON Response:
{
"_embedded": {
"people": [
{
"id": 35356,
"name": "Jon",
"description": "Test",
"type": "person",
"_links": {
"self": {
"href": "http://localhost/api/v1/50452/people/35356"
},
"items": {
"href": "http://localhost/api/v1/50452/items?person_id=35356"
},
"enabled_services": [
{
"title": "Water Company",
"href": "http://localhost/api/v1/50452/services/103890"
}
]
}
},
{
"id": 46363,
"name": "Kevin",
"description": "",
"type": "person",
"_links": {
"self": {
"href": "http://localhost/api/v1/50452/people/46363"
},
"items": {
"href": "http://localhost/api/v1/50452/items?person_id=46363"
},
"enabled_services": [
{
"title": "Water Company",
"href": "http://localhost/api/v1/50452/services/103890"
}
]
}
}
]
},
"_links": {
"self": {
"href": "http://localhost/api/v1/50452/people"
}
}
}
Our code:
ParameterizedTypeReference<Resources<Person>> resource = new ParameterizedTypeReference<Resources<Person>>() {};
Traverson traverson = new Traverson(new URI("http://localhost/api/v1/people"), MediaType.APPLICATION_JSON_UTF8);
// Create our own LinkDiscoverer as our service returns application/json instead of application/json+hal
List<LinkDiscoverer> linkDiscoverers = new ArrayList<>();
linkDiscoverers.add(new JsonPathLinkDiscoverer("$._links..['%s']..href", MediaType.APPLICATION_JSON_UTF8));
traverson.setLinkDiscoverers(linkDiscoverers);
HttpHeaders headers = new HttpHeaders();
headers.add("App-Key", Globals.Appkey);
headers.add("App-Id", Globals.AppId);
Resources<Person> personResources = traverson.follow("people").withHeaders(headers).toObject(resource);
However we are getting the following error:
java.lang.IllegalStateException: Expected to find link with rel 'people' in response {"_embedded":{"people":[{"id":31350,"name":"Jon Blue","description":"Developer","type":"person","deleted":false,"disabled":false,"company_id":50452,"order":31350,"phone_prefix":"44","_links":{"self":{"href":"http://localhost/api/v1/50452/people/31350"},"items":{"href":"http://localhost/api/v1/50452/items?person_id=31350"},"enabled_services":[{"title":"Water ...
Based on the (very limited) client docs this seems to be the correct way to do things. Does anyone know what we might be missing here?
Thanks
The Traverson is meant to be used to follow links:
Component to ease traversing hypermedia APIs by following links with
relation types. Highly inspired by the equally named JavaScript
library.
There is no link with rel people in your response, so it cannot be followed.
I could imagine you wanted to call the top-level resource that has a link to people:
Traverson traverson = new Traverson(new URI("http://localhost/api/v1/"), MediaType.APPLICATION_JSON_UTF8);
Otherwise I would suggest to use a RestTemplate to get the Resource:
restTemplate.exchange(
URI.create("http://localhost/api/v1/people"),
HttpMethod.GET,
new HttpEntity<Void>(headers),
resource).getBody();