使用Cassandra，Astra，Rest＆GraphQL构建仪表板 - 录制状态更新

CREATE TABLE events (
    avenger text,
    timestamp timestamp,
    latitude decimal,
    longitude decimal,
    status decimal,
    PRIMARY KEY (avenger, timestamp)
) WITH CLUSTERING ORDER BY (timestamp DESC);

@Repository
public class RestClient {
  @Value("https://${ASTRA_DB_ID}-${ASTRA_DB_REGION}.apps.astra.datastax.com/api/rest/v2/keyspaces/${ASTRA_DB_KEYSPACE}")
  private String baseUrl;
  @Value("${ASTRA_DB_APPLICATION_TOKEN}")
  private String token;
  private RestTemplate restTemplate;
  public RestClient() {
    this.restTemplate = new RestTemplate();
    this.restTemplate.setRequestFactory(new HttpComponentsClientHttpRequestFactory());
  }
  public <T> void createRecord(String table, T record) {
    var uri = UriComponentsBuilder.fromHttpUrl(baseUrl)
      .pathSegment(table)
      .build()
      .toUri();
    var request = RequestEntity.post(uri)
      .header("X-Cassandra-Token", token)
      .body(record);
    restTemplate.exchange(request, Map.class);
  }
}

@Repository
public class GraphqlClient {
  @Value("https://${ASTRA_DB_ID}-${ASTRA_DB_REGION}.apps.astra.datastax.com/api/graphql/${ASTRA_DB_KEYSPACE}")
  private String baseUrl;
  @Value("${ASTRA_DB_APPLICATION_TOKEN}")
  private String token;
  private RestTemplate restTemplate;
  public GraphqlClient() {
    this.restTemplate = new RestTemplate();
    this.restTemplate.setRequestFactory(new HttpComponentsClientHttpRequestFactory());
  }
  public <T> T query(String query, Class<T> cls) {
    var request = RequestEntity.post(baseUrl)
      .header("X-Cassandra-Token", token)
      .body(Map.of("query", query));
    var response = restTemplate.exchange(request, cls);
  
    return response.getBody();
  }
}

public record Event(String avenger, 
  String timestamp,
  Double latitude,
  Double longitude,
  Double status) {}

@Service
public class EventsService {
  @Autowired
  private RestClient restClient;
  public void createEvent(String avenger, Double latitude, Double longitude, Double status) {
    var event = new Event(avenger, Instant.now().toString(), latitude, longitude, status);
    restClient.createRecord("events", event);
  }
}

@RestController
public class UpdateController {
  ......
  @Autowired
  private EventsService eventsService;
  @PostMapping("/update/{avenger}")
  public void update(@PathVariable String avenger, @RequestBody UpdateBody body) throws Exception {
    eventsService.createEvent(avenger, body.lat(), body.lng(), body.status());
    statusesService.updateStatus(avenger, lookupLocation(body.lat(), body.lng()), getStatus(body.status()));
  }
  ......
}

public record EventSummary(String timestamp,
  Double latitude,
  Double longitude,
  Double status) {}

public record Events(List<EventSummary> values, String pageState) {}

public class EventsService {
  ......
  @Autowired
  private GraphqlClient graphqlClient;
  public Events getEvents(String avenger, String offset) {
    var query = "query {" + 
      "  events(filter:{avenger:{eq:\"%s\"}}, orderBy:[timestamp_DESC], options:{pageSize:5, pageState:%s}) {" +
      "    pageState " +
      "    values {" +
      "     timestamp " +
      "     latitude " +
      "     longitude " +
      "     status" +
      "   }" +
      "  }" +
      "}";
    var fullQuery = String.format(query, avenger, offset == null ? "null" : "\"" + offset + "\"");
    return graphqlClient.query(fullQuery, EventsGraphqlResponse.class).data().events();
  }
  private static record EventsResponse(Events events) {}
  private static record EventsGraphqlResponse(EventsResponse data) {}
}

public class StatusesController {
  ......
  @Autowired
  private EventsService eventsService;
  @GetMapping("/avenger/{avenger}")
  public Object getAvengerStatus(@PathVariable String avenger, @RequestParam(required = false) String page) {
    var result = new ModelAndView("dashboard");
    result.addObject("avenger", avenger);
    result.addObject("statuses", statusesService.getStatuses());
    result.addObject("events", eventsService.getEvents(avenger, page));
    return result;
  }
}

......
    <div th:if="${events}">
      <div class="row">
        <table class="table">
          <thead>
            <tr>
              <th scope="col">Timestamp</th>
              <th scope="col">Latitude</th>
              <th scope="col">Longitude</th>
              <th scope="col">Status</th>
            </tr>
          </thead>
          <tbody>
            <tr th:each="data, iterstat: ${events.values}">
              <th scope="row" th:text="${data.timestamp}">
                </td>
              <td th:text="${data.latitude}"></td>
              <td th:text="${data.longitude}"></td>
              <td th:text="${(data.status * 100) + '%'}"></td>
            </tr>
          </tbody>
        </table>
      </div>
      <div class="row" th:if="${events.pageState}">
        <div class="col position-relative">
          <a th:href="@{/avenger/{id}(id = ${avenger}, page = ${events.pageState})}"
            class="position-absolute top-50 start-50 translate-middle">Next
            Page</a>
        </div>
      </div>
    </div>
  </div>
......

......
  <a th:href="@{/avenger/{id}(id = ${data.avenger})}">
    <h5 class="card-title" th:text="${data.name}"></h5>
  </a>
......