Fix for exception on export (#1968)

This fixes an exception that would happen if three conditions were met:
  1) No database was selected or it was empty
  2) A custom export filename was set
  3) You tried to export the result of a custom query

3 files changed, 20 insertions, 1 deletions

diff --git a/Source/SPArrayAdditions.h b/Source/SPArrayAdditions.h
index 565e0393..cf3673d5 100644
--- a/Source/SPArrayAdditions.h
+++ b/Source/SPArrayAdditions.h
@@ -86,4 +86,14 @@ static inline void NSMutableArrayReplaceObject(NSArray *self, CFIndex idx, id an
 
 - (NSArray *)subarrayWithIndexes:(NSIndexSet *)indexes;
 
+/**
+ * Variant of objectAtIndex: that avoids the "index out of bounds" exception by
+ * just returning nil instead.
+ *
+ * @warning This method is NOT thread-safe.
+ * @param index  An index
+ * @return The object located at index or nil.
+ */
+- (id)objectOrNilAtIndex:(NSUInteger)index;
+
 @end
diff --git a/Source/SPArrayAdditions.m b/Source/SPArrayAdditions.m
index 91af56e4..0fe75483 100644
--- a/Source/SPArrayAdditions.m
+++ b/Source/SPArrayAdditions.m
@@ -145,4 +145,11 @@
 	return subArray;
 }
 
+- (id)objectOrNilAtIndex:(NSUInteger)index
+{
+	if([self count] <= index)
+		return nil;
+	return [self objectAtIndex:index];
+}
+
 @end
diff --git a/Source/SPExportFilenameUtilities.m b/Source/SPExportFilenameUtilities.m
index d9637e4d..71422b28 100644
--- a/Source/SPExportFilenameUtilities.m
+++ b/Source/SPExportFilenameUtilities.m
@@ -47,7 +47,8 @@
 		// Get the current export file extension
 		NSString *extension = [self currentDefaultExportFileExtension];
 		
-		filename = [self expandCustomFilenameFormatUsingTableName:[[tablesListInstance tables] objectAtIndex:1]];
+		//note that there will be no tableName if the export is done from a query result without a database selected (or empty).
+		filename = [self expandCustomFilenameFormatUsingTableName:[[tablesListInstance tables] objectOrNilAtIndex:1]];
 		
 		if (![[filename pathExtension] length] && [extension length] > 0) filename = [filename stringByAppendingPathExtension:extension];
 	}
@@ -319,6 +320,7 @@
  * Uses the current custom filename field as a data source.
  *
  * @param table  A table name to be used within the expanded filename.
+ *               Can be nil.
  *
  * @return The expanded filename.
  */