Use a const sqlite::Row to load the cache key

src/Folder.cpp

@@ -37,7 +37,7 @@ namespace policy
         return self->path();
     }
 
-    FolderCache::KeyType FolderCache::key(sqlite::Row& row )
+    FolderCache::KeyType FolderCache::key(const sqlite::Row& row )
     {
         return row.load<FolderCache::KeyType>( 1 );
     }

src/Folder.h

@@ -47,7 +47,7 @@ struct FolderCache
 {
     using KeyType = std::string;
     static const KeyType& key( const IFolder* self );
-    static KeyType key( sqlite::Row& row );
+    static KeyType key( const sqlite::Row& row );
 };
 
 }

src/Label.cpp

@@ -95,7 +95,7 @@ const std::string&policy::LabelCachePolicy::key( const ILabel* self )
     return self->name();
 }
 
-std::string policy::LabelCachePolicy::key(sqlite::Row& row)
+std::string policy::LabelCachePolicy::key( const sqlite::Row& row )
 {
     return row.load<KeyType>( 1 );
 }

src/Label.h

@@ -45,7 +45,7 @@ struct LabelCachePolicy
 {
     typedef std::string KeyType;
     static const std::string& key(const ILabel* self );
-    static std::string key( sqlite::Row& row );
+    static std::string key( const sqlite::Row& row );
 };
 
 }

src/Media.cpp

@@ -353,7 +353,7 @@ const std::string& policy::MediaCache::key( const IMedia* self )
     return self->mrl();
 }
 
-std::string policy::MediaCache::key(sqlite::Row& row)
+std::string policy::MediaCache::key( const sqlite::Row& row )
 {
     return row.load<std::string>( 5 );
 }

src/Media.h

@@ -53,7 +53,7 @@ struct MediaCache
 {
     typedef std::string KeyType;
     static const std::string& key(const IMedia* self);
-    static std::string key( sqlite::Row& row );
+    static std::string key( const sqlite::Row& row );
 };
 }
 

src/database/Cache.h

@@ -40,7 +40,7 @@ class PrimaryKeyCacheKeyPolicy
         {
             return self->id();
         }
-        static unsigned int key( sqlite::Row& row )
+        static unsigned int key( const sqlite::Row& row )
         {
             return row.load<unsigned int>( 0 );
         }

src/database/SqliteTools.h

@@ -74,7 +74,7 @@ public:
      * @brief Returns the value in column idx, but doesn't advance to the next column
      */
     template <typename T>
-    T load(unsigned int idx)
+    T load(unsigned int idx) const
     {
         if ( m_idx + 1 > m_nbColumns )
             throw errors::ColumnOutOfRange( m_idx, m_nbColumns );