[sling-org-apache-sling-graphql-core] 03/03: SLING-10541 - fix error with empty result set

[bd...@apache.org]

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bdelacretaz pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/sling-org-apache-sling-graphql-core.git

commit de82d3b80f921515b3e901ee8dba38986de28161
Author: Bertrand Delacretaz <bd...@apache.org>
AuthorDate: Thu Jun 24 15:15:14 2021 +0200

    SLING-10541 - fix error with empty result set
---
 .../java/org/apache/sling/graphql/helpers/GenericConnection.java  | 3 ++-
 .../sling/graphql/core/pagination/GenericConnectionTest.java      | 8 ++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/main/java/org/apache/sling/graphql/helpers/GenericConnection.java b/src/main/java/org/apache/sling/graphql/helpers/GenericConnection.java
index aaefe55..7b3d1be 100644
--- a/src/main/java/org/apache/sling/graphql/helpers/GenericConnection.java
+++ b/src/main/java/org/apache/sling/graphql/helpers/GenericConnection.java
@@ -74,6 +74,7 @@ public final class GenericConnection<T> implements Connection<T>, PageInfo {
             throw new IllegalStateException("Already initialized");
         }
         initialized = true;
+        final boolean anyData = dataIterator.hasNext();
 
         // Need to visit the stream first to setup the PageInfo, which graphql-java
         // apparently uses before visiting all the edges
@@ -111,7 +112,7 @@ public final class GenericConnection<T> implements Connection<T>, PageInfo {
             }
         }
 
-        if(!inRange && limit > 0) {
+        if(anyData && !inRange && limit > 0) {
             throw new SlingGraphQLException("Start cursor not found in supplied data:" + startAfter);
         }
         if(hasPreviousPage == null) {
diff --git a/src/test/java/org/apache/sling/graphql/core/pagination/GenericConnectionTest.java b/src/test/java/org/apache/sling/graphql/core/pagination/GenericConnectionTest.java
index d71d09a..a531ebf 100644
--- a/src/test/java/org/apache/sling/graphql/core/pagination/GenericConnectionTest.java
+++ b/src/test/java/org/apache/sling/graphql/core/pagination/GenericConnectionTest.java
@@ -19,10 +19,12 @@
 package org.apache.sling.graphql.core.pagination;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -185,4 +187,10 @@ public class GenericConnectionTest {
             assertTrue(iex.getMessage().contains("aximum"));
         }
     }
+
+    @Test
+    public void testEmptyResultSet() {
+        final Connection<String> empty = new GenericConnection.Builder<String>(Collections.emptyIterator(), s -> s).build();
+        assertFalse("Expecting no data", empty.getEdges().iterator().hasNext());
+    }
 }