Saving product deletes tier price and group price

Question

I've got a problem when programatically saving a product.

While loading the product with help of the product collection or the model (by attribute), setting some value and then saving it, I'm losing the tier and group prices.

$productList = Mage::getModel ( 'catalog/product' )->getCollection ()
  ->addFieldToFilter('color', $color)
  ->load();
foreach($productList as  $product) {
    $product->setColor($newColor);
    $product->save();
}

One can do a workaround by doing one of these:

1.Reload each product:

$productList = Mage::getModel ( 'catalog/product' )->getCollection ()
  ->addFieldToFilter('color', $color)
  ->load();
foreach($productList as  $product) {
    $product = Mage::helper('catalog/product')->getProduct($product->getId());
    $product->setColor($newColor);
    $product->save();
}

2.Load tier and group price (source):

$productList = Mage::getModel ( 'catalog/product' )->getCollection ()
  ->addFieldToFilter('color', $color)
  ->load();
foreach($productList as  $product) {
    $product->getTierPrice(); 
    $product->getGroupPrice();
    $product->setColor($newColor);
    $product->save();
}

minimal variant of reloading (for example) the tier price attribute (extracted from Mage_Catalog_Model_Product_Type_Price::getTierPrice():

$attribute = $product->getResource()->getAttribute('tier_price');
if($attribute){
    $attribute->getBackend()->afterLoad($product);
}

3.Add dummy values (source):

$productList = Mage::getModel ( 'catalog/product' )->getCollection ()
  ->addFieldToFilter('color', $color)
  ->load();
foreach($productList as  $product) {
    $product->setTierPrice ( array (
        'website_id' => 0,
        'cust_group' => 2,
        'price_qty' => 3,
        'price' => 10 
    ) );
    $product->setGroupPrice ( array (
        'website_id' => 0,
        'cust_group' => 2,
        'price' => 10 
    ) );
    $product->setColor($newColor);
    $product->save();
}

All these workarounds have one problem: more database calls. When often running scripts that update a lot of products, it is bad to have even more database calls only for not to lose the tier and group prices.

One can add the tier prices while building up the collection:

$productList = Mage::getModel ( 'catalog/product' )->getCollection ()
  ->addFieldToFilter('color', $color)
  ->addTierPriceData()
  ->load();
foreach($productList as  $product) {
    $product->setColor($newColor);
    $product->save();
}

But by doing so, on save one will get a constraint violation error. It seems in this case Magento tries to save the exact same tier prices again.

Does anyone know a solution which loads the tier and group prices in the same query that is used by the product collection and does not trigger constraint violations on save?

I have also posted this question in the StackOverflow part of StackExchange: https://stackoverflow.com/questions/27900130/saving-product-deletes-tier-price-and-group-price

Answer 1

you should never call save without calling load first on a product instance.
A save without a load (on a product from a collection for example) will lead to loss of data.
If you only want to update a single attribute value for a product do this:

Mage::getSingleton('catalog/product_action')->updateAttributes(
    array($attributeId),
    array('attribute_code' => 'attribute_value'),
    $storeId
);

$storeId is the storeview for which you want to update the value. For default values use 0.

Answer 2

Try this

$product->setTierPrice ( array(array (
        'website_id' => 0,
        'cust_group' => 2,
        'price_qty' => 3,
        'price' => 10 
    )) );

Its should be array of arrays