Fix using limit=0 and details=on to get only the count of elements (prelanding)

CHANGES_NEXT_RELEASE

@@ -1,3 +1,4 @@
+- Fix: allow limit=0 in all paginated operations in the NGSIv2 API (entities, entity types, subscriptions and registrations) (#1492)
 - Add: conditions.alterationTypes subscription fuctionality (#1494)
 - Add: alterationType built-in atrribute in notifications (#1494)
 - Fix: covered notifications in subscriptions (#3693)

src/lib/mongoBackend/MongoGlobal.cpp

@@ -1592,7 +1592,8 @@ bool entitiesQuery
   int             errType;
   std::string     nextErr;
 
-  while (cursor.next(&r, &errType, &nextErr))
+  /* Note limit != 0 will cause skipping the while loop in case request didn't actually ask for any result */
+  while ((limit != 0) && (cursor.next(&r, &errType, &nextErr)))
   {
     alarmMgr.dbErrorReset();
 

src/lib/mongoBackend/mongoGetSubscriptions.cpp

@@ -337,10 +337,11 @@ void mongoListSubscriptions
   TIME_STAT_MONGO_READ_WAIT_STOP();
 
   /* Process query result */
+  /* Note limit != 0 will cause skipping the while loop in case request didn't actually ask for any result */
   unsigned int docs = 0;
 
   orion::BSONObj  r;
-  while (cursor.next(&r))
+  while ((limit != 0) && (cursor.next(&r)))
   {
     docs++;
     LM_T(LmtMongo, ("retrieved document [%d]: '%s'", docs, r.toString().c_str()));

src/lib/mongoBackend/mongoQueryTypes.cpp

@@ -572,7 +572,8 @@ HttpStatusCode mongoEntityTypes
   unsigned int docs = 0;
   while (cursor.next(&resultItem))
   {
-    if ((docs < offset) || (docs > offset + limit - 1))
+    // Note limit == 0 has to be checked individually given doc > offset + limit - 1 doesn't work if offset == 0 with unsigned int */
+    if ((limit == 0) || (docs < offset) || (docs > offset + limit - 1))
     {
       docs++;
       continue;
@@ -630,6 +631,7 @@ HttpStatusCode mongoEntityTypes
 
     responseP->entityTypeVector.push_back(entityType);
   }
+
   orion::releaseMongoConnection(connection);
 
   // Get count if user requested (i.e. if totalTypesP is not NULL)

src/lib/mongoBackend/mongoRegistrationGet.cpp

@@ -374,9 +374,10 @@ void mongoRegistrationsGet
   TIME_STAT_MONGO_READ_WAIT_STOP();
 
   /* Process query result */
+  // Note limit != 0 will cause skipping the while loop in case request didn't actually ask for any result */
   int docs = 0;
   orion::BSONObj        r;
-  while (cursor.next(&r))
+  while ((limit != 0) && (cursor.next(&r)))
   {
     ngsiv2::Registration  reg;
 

src/lib/rest/rest.cpp

@@ -158,7 +158,7 @@ static int uriArgumentGet(void* cbDataP, MHD_ValueKind kind, const char* ckey, c
     {
       if ((*cP < '0') || (*cP > '9'))
       {
-        OrionError error(SccBadRequest, std::string("Bad pagination limit: /") + value + "/ [must be a decimal number]");
+        OrionError error(SccBadRequest, std::string("Bad pagination limit: /") + value + "/ [must be a positive integer number]");
         ciP->httpStatusCode = error.code;
         ciP->answer         = error.smartRender(ciP->apiVersion);
         return MHD_YES;
@@ -175,13 +175,6 @@ static int uriArgumentGet(void* cbDataP, MHD_ValueKind kind, const char* ckey, c
       ciP->answer         = error.smartRender(ciP->apiVersion);
       return MHD_YES;
     }
-    else if (limit == 0)
-    {
-      OrionError error(SccBadRequest, std::string("Bad pagination limit: /") + value + "/ [a value of ZERO is unacceptable]");
-      ciP->httpStatusCode = error.code;
-      ciP->answer         = error.smartRender(ciP->apiVersion);
-      return MHD_YES;
-    }
   }
   else if (key == URI_PARAM_PAGINATION_DETAILS)
   {

test/functionalTest/cases/0000_bad_requests/pagination_error_in_uri_params.test

@@ -43,10 +43,19 @@ orionCurl --url "$url" --payload "$payload"
 echo
 echo
 
-
+# After fixing issue #1492 this has become a not-bad request case, but we keep
+# in this file for simplicity (NGSIv1 is a deprecated API)
 echo "+++++ 3. URI param 'limit' == 0"
 url="/v1/queryContext?limit=000000"
-payload='NO PAYLOAD NECESSARY'
+payload='{
+    "entities": [
+        {
+            "type": "",
+            "isPattern": "false",
+            "id": "EVector"
+        }
+    ]
+}'
 orionCurl --url "$url" --payload "$payload"
 echo
 echo
@@ -62,15 +71,15 @@ echo
 --REGEXPECT--
 +++++ 1. bad characters in URI param 'limit'
 HTTP/1.1 400 Bad Request
-Content-Length: 125
+Content-Length: 134
 Content-Type: application/json
 Fiware-Correlator: REGEX([0-9a-f\-]{36})
 Date: REGEX(.*)
 
 {
     "orionError": {
         "code": "400",
-        "details": "Bad pagination limit: /abc/ [must be a decimal number]",
+        "details": "Bad pagination limit: /abc/ [must be a positive integer number]",
         "reasonPhrase": "Bad Request"
     }
 }
@@ -93,17 +102,16 @@ Date: REGEX(.*)
 
 
 +++++ 3. URI param 'limit' == 0
-HTTP/1.1 400 Bad Request
-Content-Length: 135
+HTTP/1.1 200 OK
+Content-Length: 70
 Content-Type: application/json
 Fiware-Correlator: REGEX([0-9a-f\-]{36})
 Date: REGEX(.*)
 
 {
-    "orionError": {
-        "code": "400",
-        "details": "Bad pagination limit: /000000/ [a value of ZERO is unacceptable]",
-        "reasonPhrase": "Bad Request"
+    "errorCode": {
+        "code": "404",
+        "reasonPhrase": "No context element found"
     }
 }
 

test/functionalTest/cases/1492_limit_zero/limit_zero_entities.test

@@ -0,0 +1,142 @@
+# Copyright 2021 Telefonica Investigacion y Desarrollo, S.A.U
+#
+# This file is part of Orion Context Broker.
+#
+# Orion Context Broker is free software: you can redistribute it and/or
+# modify it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# Orion Context Broker is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero
+# General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with Orion Context Broker. If not, see http://www.gnu.org/licenses/.
+#
+# For those usages not covered by this license please contact with
+# iot_support at tid dot es
+
+# VALGRIND_READY - to mark the test ready for valgrindTestSuite.sh
+
+--NAME--
+limit_zero_entities
+
+--SHELL-INIT--
+dbInit CB
+brokerStart CB
+
+--SHELL--
+
+#
+# 01. GET /v2/entities with 'limit' == 0 and options=count and see no entities and fiware-total-count: 0
+# 02. POST /v2/entities to create E1 entity
+# 03. POST /v2/entities to create E2 entity
+# 04. GET /v2/entities with 'limit' == 0 and options=count and see no entities and fiware-total-count: 2
+# 05. GET /v2/entities with 'limit' == 0 and see no entities
+#
+
+echo "01. GET /v2/entities with 'limit' == 0 and options=count and see no entities and fiware-total-count: 0"
+echo "======================================================================================================"
+orionCurl --url "/v2/entities?limit=0&options=count"
+echo
+echo
+
+
+echo "02. POST /v2/entities to create E1 entity"
+echo "========================================="
+payload='{
+  "id": "E1",
+  "type": "T"
+}'
+orionCurl --url /v2/entities -X POST --payload "$payload"
+echo
+echo
+
+
+echo "03. POST /v2/entities to create E2 entity"
+echo "========================================="
+payload='{
+  "id": "E2",
+  "type": "T"
+}'
+orionCurl --url /v2/entities -X POST --payload "$payload"
+echo
+echo
+
+
+echo "04. GET /v2/entities with 'limit' == 0 and options=count and see no entities and fiware-total-count: 2"
+echo "======================================================================================================"
+orionCurl --url "/v2/entities?limit=0&options=count"
+echo
+echo
+
+
+echo "05. GET /v2/entities with 'limit' == 0 and see no entities"
+echo "=========================================================="
+orionCurl --url "/v2/entities?limit=0"
+echo
+echo
+
+
+
+--REGEXPECT--
+01. GET /v2/entities with 'limit' == 0 and options=count and see no entities and fiware-total-count: 0
+======================================================================================================
+HTTP/1.1 200 OK
+Content-Length: 2
+Content-Type: application/json
+Fiware-Total-Count: 0
+Fiware-Correlator: REGEX([0-9a-f\-]{36})
+Date: REGEX(.*)
+
+[]
+
+
+02. POST /v2/entities to create E1 entity
+=========================================
+HTTP/1.1 201 Created
+Content-Length: 0
+Location: /v2/entities/E1?type=T
+Fiware-Correlator: REGEX([0-9a-f\-]{36})
+Date: REGEX(.*)
+
+
+
+03. POST /v2/entities to create E2 entity
+=========================================
+HTTP/1.1 201 Created
+Content-Length: 0
+Location: /v2/entities/E2?type=T
+Fiware-Correlator: REGEX([0-9a-f\-]{36})
+Date: REGEX(.*)
+
+
+
+04. GET /v2/entities with 'limit' == 0 and options=count and see no entities and fiware-total-count: 2
+======================================================================================================
+HTTP/1.1 200 OK
+Content-Length: 2
+Content-Type: application/json
+Fiware-Total-Count: 2
+Fiware-Correlator: REGEX([0-9a-f\-]{36})
+Date: REGEX(.*)
+
+[]
+
+
+05. GET /v2/entities with 'limit' == 0 and see no entities
+==========================================================
+HTTP/1.1 200 OK
+Content-Length: 2
+Content-Type: application/json
+Fiware-Correlator: REGEX([0-9a-f\-]{36})
+Date: REGEX(.*)
+
+[]
+
+
+--TEARDOWN--
+brokerStop CB
+dbDrop CB