SERVER-6400: FieldRef support for sub dottedField

3 files changed, 20 insertions, 6 deletions

diff --git a/src/mongo/db/field_ref.cpp b/src/mongo/db/field_ref.cpp
index 68ab798b320..bc59e6583f6 100644
--- a/src/mongo/db/field_ref.cpp
+++ b/src/mongo/db/field_ref.cpp
@@ -101,15 +101,16 @@ namespace mongo {
         _replacements.clear();
     }
 
-    std::string FieldRef::dottedField() const {
+    std::string FieldRef::dottedField( size_t offset ) const {
         std::string res;
-        if (_size == 0) {
+
+        if (_size == 0 || offset >= numParts() ) {
             return res;
         }
 
-        res.append(_fixed[0].rawData(), _fixed[0].size());
-        for (size_t i=1; i<_size; i++) {
-            res.append(1, '.');
+        for (size_t i=offset; i<_size; i++) {
+            if ( i > offset )
+                res.append(1, '.');
             StringData part = getPart(i);
             res.append(part.rawData(), part.size());
         }
diff --git a/src/mongo/db/field_ref.h b/src/mongo/db/field_ref.h
index ecc94bce046..e61192d47fc 100644
--- a/src/mongo/db/field_ref.h
+++ b/src/mongo/db/field_ref.h
@@ -66,7 +66,7 @@ namespace mongo {
          * Returns a copy of the full dotted field in its current state (i.e., some parts may
          * have been replaced since the parse() call).
          */
-        std::string dottedField() const;
+        std::string dottedField( size_t offset = 0 ) const;
 
         /**
          * Resets the internal state. See note in parse() call.
diff --git a/src/mongo/db/field_ref_test.cpp b/src/mongo/db/field_ref_test.cpp
index 5c2b6dda00e..7dbd7a3359e 100644
--- a/src/mongo/db/field_ref_test.cpp
+++ b/src/mongo/db/field_ref_test.cpp
@@ -157,4 +157,17 @@ namespace {
         ASSERT( !a.equalsDottedField( "a.b.c" ) );
     }
 
+    TEST( DottedField, Simple1 ) {
+        FieldRef a;
+        a.parse( "a.b.c.d.e" );
+        ASSERT_EQUALS( "a.b.c.d.e", a.dottedField() );
+        ASSERT_EQUALS( "a.b.c.d.e", a.dottedField(0) );
+        ASSERT_EQUALS( "b.c.d.e", a.dottedField(1) );
+        ASSERT_EQUALS( "c.d.e", a.dottedField(2) );
+        ASSERT_EQUALS( "d.e", a.dottedField(3) );
+        ASSERT_EQUALS( "e", a.dottedField(4) );
+        ASSERT_EQUALS( "", a.dottedField(5) );
+        ASSERT_EQUALS( "", a.dottedField(6) );
+    }
+
 } // namespace mongo