I have created custom gallery extension but I need to implement an import and export or gallery data in the CSV Format.
I did too much research but couldn't find any useful link to find solution so please let me know if anybody had idea for this.
For a CSV exports you can generate a grid with your data and use the
getCsv() function. Sounds overhead, but that's exactly what the export of the Tablerates shipping cost table in the backend does.
For the import you could also have a look at this module (
Mage_Shipping_Model_Resource_Carrier_Tablerate::uploadAndImport) or on the import module for product data (
Mage_ImportExport), but this is much more complicated.