invoicing : Generating invoices

The lino_xl.lib.invoicing plugin adds functionality for invoicing, i.e. automatically generating invoices from data in the database.

This document describes some general aspects of invoicing and how applications can handle this topic. More aspects in Invoicing in Lino Voga (lino_voga.lib.invoicing) and How Lino Tera generates invoices.

You should have read invoicing: Generate invoices, sales : Product invoices and Accounting stuff in Lino.

This is a tested document. The following instructions are used for initialization:

>>> from lino import startup
>>> startup('lino_book.projects.roger.settings.demo')
>>> from lino.api.doctest import *
>>> ses = rt.login("robin")
>>> translation.activate('en')

Overview

As an application developer you define invoice generators by having one or several models of your application inherit from InvoiceGenerator.

invoice generator

A database object that can generate invoices.

API

On the API level it defines the InvoiceGenerator mixin.

This plugin requires the lino_xl.lib.sales plugin.

>>> dd.plugins.invoicing.needs_plugins
['lino_xl.lib.sales']

The plugin adds a main menu command Sales ‣ Generate invoices:

>>> show_menu_path(invoicing.Plan.start_plan)
Sales --> Generate invoices

The InvoiceGenerator model mixin

class lino_xl.lib.invoicing.InvoiceGenerator

Mixin for Django models that represent an invoice generator.

The application developer must implement a method get_invoiceable_events().

Methods and class attributes:

default_invoiceable_qty

The default value to return by get_invoiceable_qty().

get_invoice_items(self, info, invoice, ar)

Yield one or several invoice items generated by this object.

These must be instances of lino_xl.lib.sales.InvoiceItem.

get_invoiceable_events(self, start_date, max_date)

Return a Django query that represents the invoicing events.

The query must be sorted in the order they are to be considered for invoicing.

get_invoiceable_event_formatter(self)

Return a callable that formats an invoicing event as an HTML etree element.

get_generators_for_plan(cls, plan, partner=None)

Return a queryset of the database objects (of this model) that potentially will generate an invoice item.

This is a pre-selection, not every object must actually produce an invoice item.

If a partner is given, use it as an additional filter condition. Be aware that the partner here is the invoice recipient, not the invoiceable partner. So when filtering on the partner, this must add a "reverse mirroring" of the way we get the invoice recipient from the invoiceable partner. For example:

if partner:
    q1 = models.Q(
        pupil__salesrule__invoice_recipient__isnull=True, pupil=pupil)
    q2 = models.Q(pupil__salesrule__invoice_recipient=partner)
    qs = qs.filter(models.Q(q1 | q2))
get_invoiceable_partner(self, plan)

Return the invoiceable partner.

To be implemented by subclasses.

get_invoiceable_product(self, plan)

Return the product to put into the generated invoice item.

To be implemented by subclasses.

>>> obj = rt.models.courses.Enrolment.objects.all()[0]
>>> print(obj.get_invoiceable_product())
Journeys
get_invoiceable_qty(self)

Return the quantity to use for the generated invoice item.

May be overridden by subclasses. The default implementation simply returns default_invoiceable_qty.

>>> obj = rt.models.courses.Enrolment.objects.all()[0]
>>> print(obj.get_invoiceable_qty())
1
get_invoiceable_title(self, invoice=None)

Return the title to put into the generated invoice item.

May be overridden by subclasses.

invoicings

A GenericRelation to all invoice items pointing to this invoiceable.

This is preferred over get_invoicings().

get_invoicings(**kwargs)

Get a queryset with the invoicings that point to this invoiceable.

This is deprecated. Preferred way is to use invoicings.

get_last_invoicing()

Return the last invoicing that was created by this generator. According to the invoice's voucher_date.

allow_group_invoices()

Whether this is a grouping generator, i.e. the invoicings of which can be grouped together with those of other invoice generators into a same invoice.

class lino_xl.lib.invoicing.InvoicingInfo

A volatile object in memory that holds information about a given invoicing event.

generator

The invoice generator this is about.

max_date

The latest date of events considered when computing this.

invoicings

Existing invoice items generated by this generator for earlier periods.

invoiced_qty

Sum of quantities invoiced earlier.

invoiced_events

Number of events invoiced earlier.

used_events

A list of the "events" used for computing this.

invoiceable_product

Which fee to apply. If this is None, no invoicing should get generated.

Sales rules

Every partner can have a sales rule.

class lino_xl.lib.invoicing.SalesRule

The Django model used to represent a sales rule.

partner

The partner to which this sales rule applies.

invoice_recipient

The partner who should get the invoices caused by this partner.

paper_type

The default paper type to be used for invoicing.

>>> fld = rt.models.invoicing.SalesRule._meta.get_field('invoice_recipient')
>>> print(fld.help_text)
The partner who should get the invoices caused by this partner.
class lino_xl.lib.invoicing.SalesRules

Shows the list of sales rules.

Invoicing rules

TODO: rename "flatrate" (the verbose name for Tariff) to "invoicing rule" or "invoicing asset".

Every product can have a flatrate.

class lino_xl.lib.invoicing.Tariff

The Django model used to represent a flatrate.

number_of_events

Number of invoicing events paid per invoicing.

For example in Lino Voga when a customer buys one ticket of ten, they can attend to 10 sessions.

Each time the customer buys a new flatrate, their asset increases by this number. The asset is what the customer did already pay for. When the asset is negative, Lino invoices the quantity needed to increase the asset to min_asset.

min_asset

The minimum number of invoicing events a customer should pay in advance.

Minimum quantity of invoicing events required to trigger an invoicing.

max_asset

Maximum quantity of invoicing events to allow per invoicing.

Never invoice more than this number of events (per invoicing period)

The invoicing plan

class lino_xl.lib.invoicing.Plan

The Django model used to represent an invoicing plan.

Inherits from lino.modlib.users.UserPlan.

user

The user who manages this plan.

journal

No longer exists. Replaced by area.

area

The invoicing area of this plan.

A pointer to Area.

today

The invoice date to be used for the invoices to generate.

max_date

Don't invoice events after this date. If this is empty, Lino will use the day before the invoice date.

partner
update_plan

Update this plan (fill the list of suggestions).

execute_plan

Execute this plan (create an invoice for each selected suggestion).

start_plan(user, **options)

Start an invoicing plan for the given user on the database object defined by k and v. Where k is the name of the field used to select the plan (e.g. 'partner' or 'journal') and v is the value for that field.

This will either create a new plan, or check whether the currently existing plan for this user was for the same database object. If it was for another object, then clear all items.

fill_plan(ar)

Add items to this plan, one for each invoice to generate.

This also groups the invoiceables by their invoiceable partner.

Note a case we had (20171007) : One enrolment for Alfons whose invoice_recipient points to Erna, a second enrolment for Erna directly. The first enrolment returned Erna as Partner, the second returned Erna as Pupil, so they were not grouped.

class lino_xl.lib.invoicing.Item

The Django model used to represent a item of an invoicing plan.

The items of an invoicing plan are called suggestions.

plan
partner
generator

The invoice generator that suggests this.

This is empty for items that were suggested by a grouping generator (InvoiceGenerator.allow_group_invoices() returns True) (even when only one generator made this suggestion).

preview

A textual preview of the invoiceable items to be included in the invoice.

amount
invoice

The invoice that has been generated. This field is empty for new items. When an item has been executed, this field points to the generated invoice.

workflow_buttons

The following fields are maybe not important:

first_date
last_date
number_of_invoiceables
create_invoice(ar):

Create the invoice corresponding to this item of the plan.

class lino_xl.lib.invoicing.Plans
class lino_xl.lib.invoicing.MyPlans
class lino_xl.lib.invoicing.AllPlans
class lino_xl.lib.invoicing.Items
class lino_xl.lib.invoicing.ItemsByPlan
class lino_xl.lib.invoicing.InvoicingsByInvoiceable
class lino_xl.lib.invoicing.StartInvoicing

Start an invoicing plan for the authenticated user.

Base for StartInvoicingForPartner.

Inherits from lino.modlib.users.StartPlan and just overrides the label.

class lino_xl.lib.invoicing.StartInvoicingByArea

Start an invoicing plan for this area.

This is installed onto the VouchersByJournal table of the VoucherType for the configured voucher_model as start_invoicing.

class lino_xl.lib.invoicing.StartInvoicingForPartner

Start an invoicing plan for this partner.

This is installed onto the contacts.Partner model as start_invoicing.

class lino_xl.lib.invoicing.StartInvoicingForOrder

Start an invoicing plan for this invoicing order.

class lino_xl.lib.invoicing.ExecutePlan

Execute this invoicing plan.

Create an invoice for each selected invoicing suggestion.

class lino_xl.lib.invoicing.ExecuteItem

Create an invoice for this invoicing suggestion.

class lino_xl.lib.invoicing.ToggleSelection

Invert selection status for all invoicing suggestions.

Invoicing areas

Invoicing areas are used in Lino Presto to differentiate between activities for which invoicing is often run manually based on occasional work and those that are invoiced monthly automatically based on regular work. In Lino Tera they might get used to separate the therapy centres in different towns. In Lino Noi this is used to differentiate between (monthly) service reports and (yearly) membership fees.

The application is responsible for selecting only invoiceables that belong to the area of the current plan. For example Lino Presto does this by defining a field lino_presto.lib.cal.Room.invoicing_area.

>>> rt.show(invoicing.Areas)
===== ============= ================== ================== ======================
 No.   Designation   Designation (de)   Designation (fr)   Journal
----- ------------- ------------------ ------------------ ----------------------
 1     First         Erster             Premier            Sales invoices (SLS)
===== ============= ================== ================== ======================
class lino_xl.lib.invoicing.Area

The Django model used to represent an invoicing area.

journal

The journal into which invoices are to be generated.

Resetting title and description of a generated invoice item

When the user sets title of an automatically generated invoice item to an empty string, then Lino restores the default value for both title and description

Invoice recipient

An invoice can point to up to three partners:

The invoice recipient is the only partner to enter into the accounting. On the other hand, the invoiceable partner is the first and most important partner for the users of the system.

That's why the partner attribute (field or property) of an invoice points to the customer (or provider, if it's a purchase document). And the invoice recipient will differ from the customer only when the partner has a salesrule__invoice_recipient field. And "delivery address" is just another custom field for those who want, it is not needed by the invoicing plugin.