Impact on price per unit (combinations option) does not compute unit_price correctly

[ballashop]

Dear staff, I have a problem with "Impact on price per unit (tax excl.)" into the combination item. first change some option: Customers Setting → Groups Price display method all Groups are Tax excluded

Create new Attributes & Features add new attributes Name: Quantity Public name: Quantity Attribute type: Radio buttons

Add new values 2 pieces 6 pieces 12 pieces 26 pieces

Create new product Name: Green apple Pricing tab Price (tax excl.): 1 € Price per unit (tax excl.) 1 €

Select → Product with combinations Add all pieces value and price

Add a combination price (combination price € X less Price (tax excl.): 1 € ) 2 pieces € 2 less Price (tax excl.): 1 € = 1 € (unit cost → 1€ ) 6 pieces € 6 less Price (tax excl.): 1 € = 5 (unit cost → 1€ ) 12 pieces € 12 less Price (tax excl.): 1 € = 11 (unit cost → 1€ ) 26 pieces € 26 less Price (tax excl.): 1 € = 25 (unit cost → 1€ )

1) The price is shown correctly 2) The unit price is not! How should I manage the unit price of the combinations so that the correct unit price is always shown? If I don't add nothing, the front end show unit price like price Example for firs combination: and the second combination: What am I doing wrong? Thanks for any reply.

[prestashop-issue-bot[bot]]

Thanks for opening this issue! We will help you to keep its state consistent

[matks]

Hi @ballashop ! The description of this bug is very good (that's nice ! not everybody does it) but I need the prestashop version of your shop 😅 because this behavior might be different, depending on the version

[ballashop]

Hi @matks thanks to reply me, we use: 1.7.6.3 I apologize for forgetting it. Thanks for any reply. Balla.

[matks]

Hi @ballashop,

So I understood what is the issue here 😄 .

The unit price is actually being stored as a divisor, and applied for each of your combination.

So, when you created your product you set

• price : 1€
• unit_price: 1€ And PrestaShop is going to remember this "unit price is equal to price => it's 100%"

So, for 2 pieces, PrestaShop is going to say "price for 2 pieces is 2€, then unit price is 100% of 2€ => 2€" So, for 4 pieces, PrestaShop is going to say "price for 2 pieces is 4€, then unit price is 100% of 4€ => 4€"

=> wrong 😱

So ... one solution might be to use the following settings:

• price (for 2 apples): 2€
• unit_price: 1€ But PrestaShop is going to remember this "unit price is equal to price => it's 50%"

So, for 2 pieces, PrestaShop is going to say "price for 2 pieces is 2€, then unit price is 50% of 1€ => 1€" 🎉 So, for 4 pieces, PrestaShop is going to say "price for 4 pieces is 4€, then unit price is 50% of 4€ => 2€" NO 😱 So, for 6 pieces, PrestaShop is going to say "price for 6 pieces is 6€, then unit price is 50% of 3€ => I display 3€" NO 😱

So the root cause is that "unit price" does not work well with "impact on price".

This is definitely a buggy behavior 👍 that we need to fix so I add it to the roadmap. However it's going to require quite a lot of thoughts to fix it 😄 this is a bit complex.

@MatShir FYI, some interesting usecase

@ballashop As you probably cannot wait for the bugfix (it will probably be quite long) I can provide the 2 workarounds:

• dont display the unit price (override the Smarty template and remove it)
• you could also hardcode the unit price into the template (but if later you modify the price of your apples you'll have to modify it again)
• indicate the unit price of your apple somewhere else (in the description ?)
• if you still need this information to be displayed AND used, then you can "adjust" this unit price for each combination using the "Impact on price per unit" field but you will need to compute its value for each combination

[ballashop]

Hi, @matks @khouloudbelguith any news about this bug? At the moment we are using 1.7.6.9 Thanks a lot for any reply. Balla

[matks]

Hi @ballashop nothing new, topic is still in "To Do".

[ballashop]

@matks, thanks for the reply, we hope it will be resolved soon. Balla

[Shoprunners]

Hi, as stated out by matks, unit_price_impact entry is not really userfriendly and if you want to use it as it is, you should create a Excel table with some formulars... BUT: there is a bug in the code as well:

Class "Product", method "getProductProperties" around row 4950

replace ` if (0 != $combination->unit_price_impact && 0 != $row['unit_price_ratio']) {

        $unitPrice = ($row['price_tax_exc'] / $row['unit_price_ratio']) + $combination->unit_price_impact;          
       $row['unit_price_ratio'] = $row['price_tax_exc'] / $unitPrice;
    }`

with

` if (0 != $combination->unit_price_impact && 0 != $row[\'unit_price_ratio\']) {

        $unitPrice = ($row['price_tax_exc'] / $row['unit_price_ratio']) + $combination->unit_price_impact;          
        $main_product_price_excl = Product::getPriceStatic((int) $row['id_product'],false,null,6,null,false,true,1,true,null,null,null,$specific_prices);           
        $row['unit_price_ratio'] = $row['unit_price_ratio']*($row['price_without_reduction'] / $my_main_product_price_excl);
    }`

WHY? Because original code takes the unit_price_ration of the main product (without attributes) into account and not the unit_price_ratio of the combination. This will fail...

Since you are planning a redesign of this, I won't submit a CR but give a hint, that you might have a closer look here.

By the way: please have a closer look in the same function how the cache_key is computed. It does not take into account every argument of the function. Possible problem....

[ballashop]

@Shoprunners thanks a lot for the message and really sorry for the late. I am not a developer so I'll avoid to manage to the code, if you can do it we can contact us privately. Thanks, bye. Balla

[KoreLewi]

Hi

Any news on this? I am using PrestaShop 1.7.8.10, and the bug still here . :(

[Brig74]

Hi

Same issue here, using Prestashop 1.7.8.2. Is it resolved in the latest versions?