Inbound shipment % margin/markup

[josh-griffin]

Currently in mSupply there is a %margin field. I don't know too much about it and it's quite a pickle to figure out - need to invest more time into it.

It seems as though it might be a non-persisted field and it is just the % difference between cost and sell prices, where adjust the margin adjusts the sell price also

[mark-prins]

I didn't know - have done a little digging and come up with something helpful from the docs. Turns out that there is a preference!

Note: If you did wish to apply a different margin to the whole invoice, click the cancel button, and edit the margin for that supplier by choosing Supplier >Edit supplier and change the margin. If you wish to apply a different margin to just some lines, you can do this as you enter the lines, as long as Editing margins is enabled in the Preferences.

though the preference isn't working - there's a bug in the implementation.
there is however, a default margin on the supplier and we should probably bring that through

Calculations made in tl_calc_margin_and_sell_price - this is the key bit:

	If ([trans_line]cost_price#0)
		r_margin:=(([trans_line]sell_price-[trans_line]cost_price)/[trans_line]cost_price)*100
		r_margin:=Round(r_margin; $i_rounding_factor)
	Else 
		r_margin:=0
		[trans_line]cost_price:=[trans_line]sell_price  // If the cost price is 0 then sell the cost price same as sell price
	End if 

The margin isn't persisted though, as you say.
Initial value comes from either [name] or [item] depending on preferences. Sound like another 🐰 hole

[mark-prins]

Updated the API issue with a comment about margins. We'd need the default value somehow

[josh-griffin]

Ah thanks for looking into this. I wonder what the priority is of name or item. "if" there is a supplier margin, use that, otherwise use the item? Otherwise use nothing? Seems just a defaultMargin field on the InvoiceNode or something would work well - the backend can just decide what is meant to be used

[mark-prins]

There's a pref for that! 😁

If Item margin overrides supplier margin on Supplier Invoices (<>ipref_inv_entry ?? 27) is set to true, and the item margin is > 0 then the item margin is used. Otherwise the name margin is used. Unless that's 0 then the item margin is used.

Although, if the default price is set, then the margin is 0. That comes from [item_store_join].. specific to store and item. Could return that along with the item.

When loading a supplier invoice, the margin is calculated. If the cost & sell price are > 0 then this:
margin:=Round(((([trans_line]sell_price/[trans_line]cost_price)-1)*100); 2)
( if either cost or sell is 0 then margin = 0 )

The defaultMargin on InvoiceNode wouldn't be specific to an item - I thought that the only way would be to send a mutation to create the InvoiceLineNode and have the API fuss around with prefs and defaults. But I don't like the idea of creating InvoiceLineNodes at that point 😢 It would be a big change to the approach, makes batching requests harder, complicates the cancel action (have to delete the line again) and could be slower

To handle it client-side, we'd need the margin on item and supplier, the default price on item.. and the pref value. I'd much rather have the API handle it all - but I'm not seeing an easy way to do that. I wonder if we can ignore/remove that pref? Prefer supplier margin, but take item if no supplier margin?

[josh-griffin]

Ah..! Getting clearer 😁

Yup I think your suggestion is good:

• Ignore the prefs for now (though, I would like to start adding them sooner rather than later, they're a huge cross cutting concern so the more we put it off the more time it will consume)
• • ItemNode.defaultPrice, ItemNode.margin, NameNode.margin
• Then we just make some fn getMargin(item, name) => margin and then just add a pref parameter at some point (Which might just be some big json blob of prefs after logging in, or something?)

[josh-griffin]

As a recap since it's been so long:

• Get item.defaultPrice added to API
• Get item.margin added to API
• Get name.margin added to api
• When adding an inbound line, set the initial cost price to the default price and the initial sell price to cost * margin