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. You should have read sales : Product invoices and Accounting stuff in Lino. See also Invoicing in Lino Voga (lino_voga.lib.invoicing) and How Lino Tera generates invoices.

A tested document

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.

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 ‣ Create invoices:

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

The InvoiceGenerator model mixin

class lino_xl.lib.invoicing.InvoiceGenerator

Mixin for things that can generate invoices.

An invoice generator must produce a series of invoiceable events (the application programmer must implement a method get_invoiceable_events()). These events can be instances of any model, but the generator's get_invoiceable_event_formatter() must understand them.

Subclasses must implement the following:

default_invoiceable_qty

The default quantity to invoice

get_invoice_items(self, info, invoice, ar)
get_invoiceable_events(self, start_date, max_date)

Return a Django query that represents the invoiceable events.

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

get_invoiceable_event_formatter(self)

Return a callable which formats an invoiceable event as a HTML etree element.

get_invoiceables_for_plan(cls, plan, partner=None)

Yield a sequence of invoiceable candidates (objects of this class) for the given plan. If a partner is given, use it as an additional filter condition.

Not every yielded candidate will become an invoice. This is a pre-selection. For every candidate Lino will call get_invoiceable_product()

get_invoiceable_product(self, plan)

To be implemented by subclasses. Return the product to put into the invoice item.

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

To be implemented by subclasses. Return the quantity to put into the invoice item.

>>> 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 invoice item. May be overridden by subclasses.

The mixin adds the following methods to the model:

invoicings

A simple GenericRelation to all invoice items pointing to this enrolment.

This is preferred over get_invoicings().

get_invoicings(**kwargs)

Get a queryset with the invoicings which point to this enrolment.

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.

class lino_xl.lib.invoicing.InvoicingInfo

A volatile object which holds cached information about a given invoice generator.

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

Flatrates

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 calendar events paid per invoicing.

min_asset

Minimum quantity required to trigger an invoice.

The invoicing plan

class lino_xl.lib.invoicing.Plan

The Django model used to represent an invoicing plan.

An invoicing plan is a rather temporary database object which represents the plan of a given user to have Lino generate a series of invoices.

It 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

This 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
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.ExecutePlan

Execute this invoicing plan. Create an invoice for each selected suggestion.

class lino_xl.lib.invoicing.ExecuteItem

Create an invoice for this suggestion.

class lino_xl.lib.invoicing.ToggleSelection

Invert selection status for all suggestions.

Invoicing areas

An invoicing area is is used to classify business activities into different parts for which end users can start separate invoicing plans.

This is used in Lino Presto to differentiate between activities for which invoicing is often run manually based on occasional work from 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.

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 a flatrate.

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