On Tuesday, September 10, 2019 at 2:54:43 AM UTC-7, mostwanted wrote:
>
> I figured if I could update the amount field in db.product within the buy 
> functiontion just around the same time i'm saving inside the db.sale table 
> when purchasing then it should be easy but I am having a really hard time 
> identifying only the purchased items by their ids & subtracting their 
> quantities from similar items in db.product!
>

Don't you record the id of the item in your shopping cart?
 

>
> The code below is able to update the amount in db.product but it updates 
> for all products which is not what i want
> CODE SAMPLE 1:
> for item1 in item1:
>             diff=item1.amount-value
>

I don't think you want this line:   

>             db(db.product.amount).update(amount=diff)
>
I think it is selecting everything in db.product that has an amount.

Once you figure out how to get the id from your shopping cart, the line 
should probably be

                db(db.product.id == cart_item.id).update(amount=diff)




 

> Then i made another desperate attempt with the code below but it is not 
> updating anything at all!
> for item1 in item1:
>             for id, k in session.cart.items():
>                 if item1.id==k:
>                     diff=item1.amount-value
>                     db(db.product.amount).update(amount=diff)
>
> Anyone who can do this better please help.
>
> Regards;
>
> Mostwanted
>

/dps
 

>
> On Thursday, September 5, 2019 at 8:21:56 AM UTC+2, Dave S wrote:
>>
>>
>>
>> On Wednesday, September 4, 2019 at 10:59:21 PM UTC-7, mostwanted wrote:
>>>
>>> I have a website where I am selling items, what I desperately want to 
>>> achieve is to be able to show the buyers the remaining number of each item. 
>>> I have 2 tables, the table that has all the items being sold & has a field 
>>> amount which is the current number of items in stock and the other 
>>> table which records sales as customers buy and has a field quantity 
>>> which is the quantity of items purchased. After a customer has made a 
>>> purchase I want to be able to subtract quantity from amount and have 
>>> difference update and be the new value for amount.
>>>
>>> I wrote some controller code which is not achieving this, it is instead 
>>> updating the amount field for all items with the same figure.
>>>
>>>
>>> THE VIEW
>>>
>>> {{extend 'layout.html'}}
>>>
>>>     <div class="row">
>>> {{for p in products:}}
>>>         {{if p.product_type=="Earrings":}}
>>> <div class="clothes">
>>>     <h4 style="color: #ff69b4;">{{=p.name}}</h4>
>>>     <h7 style="color: #ff69b4;">{{=p.amount}} available in stock</h7>
>>>     <h5>
>>>         <span style="color: aqua; font-weight: 
>>> bold;">{{=MoneyFormat(p.price)}}</span>
>>>     </h5>
>>>     <img class="magnify" src="{{=URL('download',args=p.image)}}" 
>>> height="200px"/>
>>>     <br />
>>>     <span id="{{='item%s'%p.id}}" style="font-weight: bold; color: 
>>> red;">{{=session.cart.get(p.id,0)}}</span> in cart - {{=A('add to 
>>> cart',callback=URL('cart_callback',vars=dict(id=p.id,action='add')),target='item%s'%p.id,_class='button
>>>  pill')}}
>>>     <br />
>>>     <span style="font-size:12px;font-weight: bold; color: #ff69b4;">Click 
>>> the image to enlarge</span>
>>> <br />
>>> </div>
>>> {{pass}}
>>>
>>> {{pass}}
>>>         </div>
>>>
>>>
>>> THE CART_CALLBACK FUNCTION
>>>
>>>
>>> def cart_callback():
>>>     id = int(request.vars.id)
>>>     if request.vars.action == 'add':
>>>         session.cart[id]=session.cart.get(id,0)+1
>>>     if request.vars.action == 'sub':
>>>         session.cart[id]=max(0,session.cart.get(id,0)-1)
>>>     return str(session.cart[id])
>>>
>>>
>>> MY FUNCTION FOR UPDATING AFTER PURCHASES
>>>
>>> def index():
>>>     if not auth.user:
>>>         response.flash=T('PLEASE LOG IN FIRST TO BE ABLE TO GET THE MENU 
>>> AND BUY')
>>>     products = db(db.product).select(orderby=db.product.name)
>>>     num=db(db.sale).select()
>>>     for n in num:
>>>         quantity=n.quantity
>>>         if quantity is None:
>>>             quantity=0
>>>         for p in products:
>>>             amount1=p.amount-quantity
>>>             db(db.product.amount).update(amount=amount1)
>>>     return locals()
>>>
>>>
>>> What should happen is that every time a customer buys whatever number of 
>>> items a new figure showing reduction in number of items should be displayed.
>>>
>>>
>>> Regards;
>>>
>>>
>>> Mostwanted
>>>
>>>
>>>
>> index() looks like it spends a great deal of time subtracting everything 
>> in sales from everything in products.
>>
>> I think you are recording the product id in the cart.  Are you then (on 
>> check-out, I presume) recording the product id in db.sales?
>>
>> if so , then you don't need the select() on all products.
>> Instead, use the product id in each row of db.sales to select the product 
>> entry to update.
>>
>> You probably want a way to identify which rows in db.sales have already 
>> been processed (that is, which quantities have already been subtracted from 
>> the the available in the corresponding product entry).
>>
>> /dps
>>
>>  
>>
>

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