[QSqlQuery] misbehavior of seek in special query positions

When QSqlQuery::at() == QSql::BeforeFirstRow and seek(1, true) (seek to
next record) is called the expected result is go to first row.
When QSqlQuery::at() == QSql::AfterLastRow and seek(-1, true) (seek to
previous record) is called the expected result is go to last row.

But in all cases the first and last are skipped.

Change-Id: I584138b3d397ce1c790bf89688ee92289a99611c
Reviewed-by: Mark Brand <mabrand@mabrand.nl>

2 files changed, 38 insertions, 7 deletions

diff --git a/src/sql/kernel/qsqlquery.cpp b/src/sql/kernel/qsqlquery.cpp
index b08f6bc8ef..6b13eb02ed 100644
--- a/src/sql/kernel/qsqlquery.cpp
+++ b/src/sql/kernel/qsqlquery.cpp
@@ -511,12 +511,23 @@ const QSqlResult* QSqlQuery::result() const
 
   \list
 
-  \li If the result is currently positioned before the first record or
-  on the first record, and \a index is negative, there is no change,
-  and false is returned.
+  \li If the result is currently positioned before the first record and:
+  \list
+  \li \a index is negative or zero, there is no change, and false is
+  returned.
+  \li \a index is positive, an attempt is made to position the result
+  at absolute position \a index - 1, following the sames rule for non
+  relative seek, above.
+  \endlist
 
-  \li If the result is currently located after the last record, and \a
-  index is positive, there is no change, and false is returned.
+  \li If the result is currently positioned after the last record and:
+  \list
+  \li \a index is positive or zero, there is no change, and false is
+  returned.
+  \li \a index is negative, an attempt is made to position the result
+  at \a index + 1 relative position from last record, following the
+  rule below.
+  \endlist
 
   \li If the result is currently located somewhere in the middle, and
   the relative offset \a index moves the result below zero, the result
@@ -549,7 +560,7 @@ bool QSqlQuery::seek(int index, bool relative)
         switch (at()) { // relative seek
         case QSql::BeforeFirstRow:
             if (index > 0)
-                actualIdx = index;
+                actualIdx = index - 1;
             else {
                 return false;
             }
@@ -557,7 +568,7 @@ bool QSqlQuery::seek(int index, bool relative)
         case QSql::AfterLastRow:
             if (index < 0) {
                 d->sqlResult->fetchLast();
-                actualIdx = at() + index;
+                actualIdx = at() + index + 1;
             } else {
                 return false;
             }
diff --git a/tests/auto/sql/kernel/qsqlquery/tst_qsqlquery.cpp b/tests/auto/sql/kernel/qsqlquery/tst_qsqlquery.cpp
index 55cb67eed9..301c7bca51 100644
--- a/tests/auto/sql/kernel/qsqlquery/tst_qsqlquery.cpp
+++ b/tests/auto/sql/kernel/qsqlquery/tst_qsqlquery.cpp
@@ -1247,6 +1247,26 @@ void tst_QSqlQuery::seek()
     QVERIFY( q.seek( 0 ) );
     QCOMPARE( q.at(), 0 );
     QCOMPARE( q.value( 0 ).toInt(), 1 );
+
+    QVERIFY(!q.seek(QSql::BeforeFirstRow));
+    QCOMPARE(q.at(), int(QSql::BeforeFirstRow));
+    QVERIFY(q.seek(1, true));
+    QCOMPARE(q.at(), 0);
+    QCOMPARE(q.value(0).toInt(), 1);
+
+    qint32 count = 1;
+    while (q.next()) ++count;
+
+    QCOMPARE(q.at(), int(QSql::AfterLastRow));
+
+    if (!q.isForwardOnly()) {
+        QVERIFY(q.seek(-1, true));
+        QCOMPARE(q.at(), count - 1);
+        QCOMPARE(q.value(0).toInt(), count);
+    } else {
+        QVERIFY(!q.seek(-1, true));
+        QCOMPARE(q.at(), int(QSql::AfterLastRow));
+    }
 }
 
 void tst_QSqlQuery::seekForwardOnlyQuery()