ATLAS-3549 Add a new REST endpoint to get EntityHeader using unique attributes

repository/src/main/java/org/apache/atlas/repository/store/graph/AtlasEntityStore.java

@@ -72,6 +72,9 @@ public interface AtlasEntityStore {
      */
     AtlasEntityHeader getHeaderById(String guid) throws AtlasBaseException;
 
+
+    public AtlasEntityHeader getEntityHeaderByUniqueAttributes(AtlasEntityType entityType, Map<String, Object> uniqAttributes) throws AtlasBaseException;
+
     /**
      * Batch GET to retrieve entities by their ID
      * @param guid

repository/src/main/java/org/apache/atlas/repository/store/graph/v2/AtlasEntityStoreV2.java

@@ -264,6 +264,33 @@ public class AtlasEntityStoreV2 implements AtlasEntityStore {
         return ret;
     }
 
+    @Override
+    @GraphTransaction
+    public AtlasEntityHeader getEntityHeaderByUniqueAttributes(AtlasEntityType entityType, Map<String, Object> uniqAttributes) throws AtlasBaseException {
+        if (LOG.isDebugEnabled()) {
+            LOG.debug("==> getEntityHeaderByUniqueAttributes({}, {})", entityType.getTypeName(), uniqAttributes);
+        }
+
+        AtlasVertex entityVertex = AtlasGraphUtilsV2.getVertexByUniqueAttributes(entityType, uniqAttributes);
+
+        EntityGraphRetriever entityRetriever = new EntityGraphRetriever(typeRegistry);
+
+        AtlasEntityHeader ret = entityRetriever.toAtlasEntityHeader(entityVertex);
+
+        if (ret == null) {
+            throw new AtlasBaseException(AtlasErrorCode.INSTANCE_BY_UNIQUE_ATTRIBUTE_NOT_FOUND, entityType.getTypeName(),
+                    uniqAttributes.toString());
+        }
+
+        AtlasAuthorizationUtils.verifyAccess(new AtlasEntityAccessRequest(typeRegistry, AtlasPrivilege.ENTITY_READ, ret), "read entity: typeName=", entityType.getTypeName(), ", uniqueAttributes=", uniqAttributes);
+
+        if (LOG.isDebugEnabled()) {
+            LOG.debug("<== getEntityHeaderByUniqueAttributes({}, {}): {}", entityType.getTypeName(), uniqAttributes, ret);
+        }
+
+        return ret;
+    }
+
     /**
      * Check state of entities in the store
      * @param request AtlasCheckStateRequest

webapp/src/main/java/org/apache/atlas/web/rest/EntityREST.java

@@ -149,6 +149,47 @@ public class EntityREST {
     }
 
     /**
+     * Fetch AtlasEntityHeader given its type and unique attribute.
+     *
+     * In addition to the typeName path parameter, attribute key-value pair(s) can be provided in the following format
+     *
+     * attr:<attrName>=<attrValue>
+     *
+     * NOTE: The attrName and attrValue should be unique across entities, eg. qualifiedName
+     *
+     * The REST request would look something like this
+     *
+     * GET /v2/entity/uniqueAttribute/type/aType/header?attr:aTypeAttribute=someValue
+     *
+     * @param typeName
+     * @return AtlasEntityHeader
+     * @throws AtlasBaseException
+     */
+    @GET
+    @Path("/uniqueAttribute/type/{typeName}/header")
+    public AtlasEntityHeader getEntityHeaderByUniqueAttributes(@PathParam("typeName") String typeName,
+                                                               @Context HttpServletRequest servletRequest) throws AtlasBaseException {
+        Servlets.validateQueryParamLength("typeName", typeName);
+
+        AtlasPerfTracer perf = null;
+
+        try {
+            Map<String, Object> attributes = getAttributes(servletRequest);
+            if (AtlasPerfTracer.isPerfTraceEnabled(PERF_LOG)) {
+                perf = AtlasPerfTracer.getPerfTracer(PERF_LOG, "EntityREST.getEntityHeaderByUniqueAttributes(" + typeName + "," + attributes + ")");
+            }
+
+            AtlasEntityType entityType = ensureEntityType(typeName);
+
+            validateUniqueAttribute(entityType, attributes);
+
+            return entitiesStore.getEntityHeaderByUniqueAttributes(entityType, attributes);
+        } finally {
+            AtlasPerfTracer.log(perf);
+        }
+    }
+
+    /**
      * Fetch complete definition of an entity given its type and unique attribute.
      *
      * In addition to the typeName path parameter, attribute key-value pair(s) can be provided in the following format

webapp/src/test/java/org/apache/atlas/web/adapters/TestEntityREST.java

@@ -110,6 +110,55 @@ public class TestEntityREST {
         TestEntitiesREST.verifyAttributes(response.getEntity().getAttributes(), dbEntity.getAttributes());
     }
 
+    @Test
+    public void testGetEntityHeaderByUniqueAttributes() throws Exception {
+        createTestEntity();
+
+        String[] attrVal = {String.valueOf(dbEntity.getAttribute("name"))};
+
+        Map<String, String[]> paramMap = new HashMap<>();
+        paramMap.put("attr:name", attrVal);
+
+        HttpServletRequest mockRequest = Mockito.mock(HttpServletRequest.class);
+        Mockito.when(mockRequest.getParameterMap()).thenReturn(paramMap);
+
+        AtlasEntityHeader response = entityREST.getEntityHeaderByUniqueAttributes(dbEntity.getTypeName(), mockRequest);
+
+        Assert.assertNotNull(response);
+        Assert.assertEquals(dbEntity.getAttribute("name"), response.getAttribute("name"));
+        Assert.assertEquals(dbEntity.getAttribute("description"), response.getAttribute("description"));
+    }
+
+    @Test(expectedExceptions = AtlasBaseException.class)
+    public void testGetEntityHeaderByUniqueAttributes_2() throws Exception {
+        createTestEntity();
+
+        String[] attrVal = {String.valueOf(dbEntity.getAttribute("name") + "_2")};
+
+        Map<String, String[]> paramMap = new HashMap<>();
+        paramMap.put("attr:name", attrVal);
+
+        HttpServletRequest mockRequest = Mockito.mock(HttpServletRequest.class);
+        Mockito.when(mockRequest.getParameterMap()).thenReturn(paramMap);
+
+        entityREST.getEntityHeaderByUniqueAttributes(dbEntity.getTypeName(), mockRequest);
+    }
+
+    @Test(expectedExceptions = AtlasBaseException.class)
+    public void testGetEntityHeaderByUniqueAttributes_3() throws Exception {
+        createTestEntity();
+
+        String[] attrVal = {String.valueOf(dbEntity.getAttribute("description"))};
+
+        Map<String, String[]> paramMap = new HashMap<>();
+        paramMap.put("attr:description", attrVal);
+
+        HttpServletRequest mockRequest = Mockito.mock(HttpServletRequest.class);
+        Mockito.when(mockRequest.getParameterMap()).thenReturn(paramMap);
+
+        entityREST.getEntityHeaderByUniqueAttributes(dbEntity.getTypeName(), mockRequest);
+    }
+
     @Test(dependsOnMethods = "testGetEntityById")
     public void testAddAndGetClassification() throws Exception {