Magento – magento2 how to update tier price programmatically, including value type

Maybe you try to get a group price. If you want to get the tier price (http://www.magentocommerce.com/knowledge-base/entry/tier-pricing)

you should call

$prod->getTierPrice($qty);

$qty is null will return the FinalPrice instead.

reference Model -> Product

public function getTierPrice($qty=null)

You can add several tier prices for one product, so you should provide an array of objects (or arrays) to the product.

I didn't try, but I would add an array inside your array, like that :

$tierPrices = array(
                ['cust_group'    => '2',
                'price_qty' => '2',
                'price'   => $post['tprice'],
                'website_id' => '1']
             );
$product->setTierPrice($tierPrices);

EDIT

Here is a working installer code, that created me a test product with the good tier prices. I removed the index "all_groups" from the tierPrices array, because I didn't see it in my Magento. Is it an error ? A custom module ?

<?php

$installer = $this;

Mage::app()->setUpdateMode(false);
Mage::app()->setCurrentStore(1);

$product = Mage::getModel('catalog/product');
$product->setAttributeSetId(4)
    ->setTypeId('simple')
    ->setWeight(0.50)
    ->setStatus(1)
    ->setTaxClassId(2)
    ->setVisibility(Mage_Catalog_Model_Product_Visibility::VISIBILITY_NOT_VISIBLE);


$sku = strtolower("SKU");
$product->setSku($sku)
    ->setName('test product')
    ->setPrice(12)
    ->setDescription('Test Description')
    ->setShortDescription('description');

$tierPrices = array(
['cust_group' => '2',
    'price_qty' => '2',
    'price' => 11,
    'website_id' => '0']
);
$product->setTierPrice($tierPrices);
$product->save();

$installer->endSetup();