[OLINGO-438] Added count support for entity set

lib/server-api/src/main/java/org/apache/olingo/server/api/processor/EntityCollectionProcessor.java

@@ -29,11 +29,19 @@ import org.apache.olingo.server.api.uri.UriInfo;
 public interface EntityCollectionProcessor extends Processor {
 
   /**
-   * Reads entities data from persistency and puts serialized content and status into the response.
+   * Reads entities data from persistence and puts serialized content and status into the response.
    *  @param request - OData request object containing raw HTTP information
    *  @param response - OData response object for collecting response data
    *  @param uriInfo - information of a parsed OData URI
    *  @param requestedContentType - requested content type after content negotiation
    */
   void readCollection(ODataRequest request, ODataResponse response, UriInfo uriInfo, ContentType requestedContentType);
+
+  /**
+   *  Count entities from persistence and puts serialized content and status into the response.
+   *  @param request - OData request object containing raw http information.
+   *  @param response - OData response object for collecting response data
+   *  @param uriInfo - information of a parsed OData uri
+   */
+  void countCollection(ODataRequest request, ODataResponse response, UriInfo uriInfo);
 }

lib/server-core/src/main/java/org/apache/olingo/server/core/ODataHandler.java

@@ -227,6 +227,15 @@ public class ODataHandler {
         }
       }
       break;
+    case count:
+      if (request.getMethod().equals(HttpMethod.GET)) {
+        EntityCollectionProcessor cp = selectProcessor(EntityCollectionProcessor.class);
+      	cp.countCollection(request, response, uriInfo);
+      } else {
+        throw new ODataHandlerException("not implemented",
+            ODataHandlerException.MessageKeys.FUNCTIONALITY_NOT_IMPLEMENTED);
+      }
+      break;
     default:
       throw new ODataHandlerException("not implemented",
           ODataHandlerException.MessageKeys.FUNCTIONALITY_NOT_IMPLEMENTED);

lib/server-core/src/main/java/org/apache/olingo/server/core/uri/validator/UriValidator.java

@@ -521,6 +521,7 @@ public class UriValidator {
     UriResource secondLastPathSegment = uriInfo.getUriResourceParts().get(secondLastPathSegmentIndex);
     switch (secondLastPathSegment.getKind()) {
     case entitySet:
+    case navigationProperty:
       idx = RowIndexForUriType.entitySetCount;
       break;
     case complexProperty:

lib/server-core/src/test/java/org/apache/olingo/server/core/ContentNegotiatorTest.java

@@ -230,5 +230,10 @@ public class ContentNegotiatorTest {
         final ContentType requestedContentType) {
       response.setHeader(HttpHeader.CONTENT_TYPE, requestedContentType.toContentTypeString());
     }
+
+    @Override
+    public void countCollection(ODataRequest request, ODataResponse response, UriInfo uriInfo) {
+      response.setHeader(HttpHeader.CONTENT_TYPE, ContentType.TEXT_PLAIN.toContentTypeString());
+    }
   }
 }

lib/server-tecsvc/src/main/java/org/apache/olingo/server/tecsvc/processor/TechnicalProcessor.java

@@ -43,8 +43,10 @@ import org.apache.olingo.server.api.uri.UriResource;
 import org.apache.olingo.server.api.uri.UriResourceEntitySet;
 import org.apache.olingo.server.api.uri.queryoption.ExpandOption;
 import org.apache.olingo.server.api.uri.queryoption.SelectOption;
+import org.apache.olingo.server.api.uri.queryoption.SystemQueryOptionKind;
 import org.apache.olingo.server.tecsvc.data.DataProvider;
 
+import java.io.ByteArrayInputStream;
 import java.util.List;
 import java.util.Locale;
 
@@ -134,9 +136,54 @@ public class TechnicalProcessor implements EntityCollectionProcessor, EntityProc
     }
   }
 
+  @Override
+  public void countCollection(ODataRequest request, ODataResponse response, UriInfo uriInfo) {
+    try {
+      EntitySet entitySet = null;
+      final UriInfoResource uriResource = uriInfo.asUriInfoResource();
+      final List<UriResource> resourceParts = uriResource.getUriResourceParts();
+      if(isCount(resourceParts)) {
+        int pos = resourceParts.size() - 2;
+        if(pos >= 0) {
+          final UriResourceEntitySet ur =
+              (UriResourceEntitySet) uriResource.getUriResourceParts().get(pos);
+          entitySet = readEntitySetInternal(ur.getEntitySet(), true);
+        }
+      }
+
+      if (entitySet == null) {
+        response.setStatusCode(HttpStatusCode.NOT_FOUND.getStatusCode());
+      } else {
+        Integer count = entitySet.getCount();
+        response.setContent(new ByteArrayInputStream(count.toString().getBytes()));
+        response.setStatusCode(HttpStatusCode.OK.getStatusCode());
+        response.setHeader(HttpHeader.CONTENT_TYPE, "text/plain");
+      }
+    } catch (final DataProvider.DataProviderException e) {
+      response.setStatusCode(HttpStatusCode.INTERNAL_SERVER_ERROR.getStatusCode());
+    }
+  }
+
+  private boolean isCount(List<UriResource> resourceParts) {
+    if(resourceParts.isEmpty()) {
+      return false;
+    }
+    UriResource part = resourceParts.get(resourceParts.size() - 1);
+    return SystemQueryOptionKind.COUNT.toString().equals(part.toString());
+  }
+
   private EntitySet readEntitySetInternal(final EdmEntitySet edmEntitySet) throws DataProvider.DataProviderException {
+    return readEntitySetInternal(edmEntitySet, false);
+  }
+
+  private EntitySet readEntitySetInternal(final EdmEntitySet edmEntitySet,
+      boolean withCount) throws DataProvider.DataProviderException {
     EntitySet entitySet = dataProvider.readAll(edmEntitySet);
-    // TODO: set count and next link
+    // TODO: set count (correctly) and next link
+    if(withCount && entitySet.getCount() == null) {
+      entitySet.setCount(entitySet.getEntities().size());
+    }
+    //
     return entitySet;
   }
 

lib/server-test/src/test/java/org/apache/olingo/server/core/ODataHandlerTest.java

@@ -35,11 +35,14 @@ import org.apache.olingo.commons.api.http.HttpStatusCode;
 import org.apache.olingo.server.api.OData;
 import org.apache.olingo.server.api.ODataRequest;
 import org.apache.olingo.server.api.ODataResponse;
+import org.apache.olingo.server.api.processor.EntityCollectionProcessor;
 import org.apache.olingo.server.api.processor.MetadataProcessor;
 import org.apache.olingo.server.api.processor.ServiceDocumentProcessor;
+import org.apache.olingo.server.api.uri.UriInfo;
 import org.apache.olingo.server.tecsvc.provider.EdmTechProvider;
 import org.junit.Before;
 import org.junit.Test;
+import org.mockito.Mockito;
 
 public class ODataHandlerTest {
 
@@ -238,4 +241,41 @@ public class ODataHandlerTest {
     assertEquals(HttpStatusCode.NOT_IMPLEMENTED.getStatusCode(), response.getStatusCode());
   }
 
+  @Test
+  public void testCount() throws Exception {
+    ODataRequest request = new ODataRequest();
+
+    request.setMethod(HttpMethod.GET);
+    request.setRawODataPath("ESAllPrim/$count");
+
+    EntityCollectionProcessor processor = mock(EntityCollectionProcessor.class);
+    handler.register(processor);
+
+    ODataResponse response = handler.process(request);
+
+    assertNotNull(response);
+    Mockito.verify(processor).countCollection(
+    		Mockito.eq(request),
+    		Mockito.any(ODataResponse.class),
+    		Mockito.any(UriInfo.class));
+  }  
+  
+  @Test
+  public void testCountWithNavigation() throws Exception {
+    ODataRequest request = new ODataRequest();
+
+    request.setMethod(HttpMethod.GET);
+    request.setRawODataPath("ESAllPrim/NavPropertyETTwoPrimMany/$count");
+
+    EntityCollectionProcessor processor = mock(EntityCollectionProcessor.class);
+    handler.register(processor);
+
+    ODataResponse response = handler.process(request);
+
+    assertNotNull(response);
+    Mockito.verify(processor).countCollection(
+        Mockito.eq(request),
+    		Mockito.any(ODataResponse.class), 
+    		Mockito.any(UriInfo.class));
+  }  
 }