Bugfixes: Product category position lost during import

There is a strange bug in Magento version 1.6. It happened when you define products order within category and then re-import the products. After that defined positions are reverted to 1.

The problem is in the file: app/code/core/Mage/ImportExport/Model/Import/Entity/Product.php, function _saveProductCategories().

Lets study the code.
[cc lang='php' ]
if ($categoriesData) {
$categoriesIn = array();
$delProductId = array();

foreach ($categoriesData as $delSku => $categories) {
$productId = $this->_newSku[$delSku]['entity_id'];
$delProductId[] = $productId;

foreach (array_keys($categories) as $categoryId) {
$categoriesIn[] = array('product_id' => $productId, 'category_id' => $categoryId, 'position' => 1);
}
}
if (Mage_ImportExport_Model_Import::BEHAVIOR_APPEND != $this->getBehavior()) {
$this->_connection->delete(
$tableName,
$this->_connection->quoteInto('product_id IN (?)', $delProductId)
);
}
if ($categoriesIn) {
$this->_connection->insertOnDuplicate($tableName, $categoriesIn, array('position'));
}
}

As you see we set position=1, which is correct for new imported products. However then we perform insertOnDuplicate(), and if the position for this category/product already specified, it replace the position with 1 as well.

To fix this issue, you have to replace this line:

[cc lang='php' ]
if ($categoriesIn) {
$this->;_connection->;insertOnDuplicate($tableName, $categoriesIn, array('position'));
}

with the following:
[cc lang='php' ]
if ($categoriesIn) {
$this->_connection->insertOnDuplicate($tableName, $categoriesIn, array('category_id'));
}

Thus if the product position already exists in the database it will not be updated.

PLEASE BACKUP THE FILES AND DATABASE BEFORE MAKING ANY CHANGES, SERIOUSLY.