Concepts
The rules for the Formal Sector can be complex and evolving. Therefore, the "Formal Sector" solution should bring flexibility, to avoid complete redesign and databases change when a parameter to define the contribution value is changed.
To bring that flexibility, the solution described here uses a Calculation Rule (the Calculation Rules are defined in additional openIMIS modules extending the Calculation Module). This module is defining a framework to design calculations and to manage their activation and versioning in openIMIS. This solution will deliver a Calculation Module that takes the income (on the level of the Contract’s insuree) and a rate (on the level of the Contribution Plan) as parameters, make the calculation and updates the payment value of the Contract’s insuree.
The value of the parameters will be saved as a JSON string in the json_ext
field.
Later, this module could be used as a framework to create event-based actions
Business process
This module will use a "generic contribution" to get the required parameters and the json_ext
database field will be used to save the parameters (generic backend feature). Finally, a signal will trigger the calculation action.
Solution
This module will rely heavily on the django signals
In order to have a generic approach that will make the code more readable, one argument will be expected in the signal, this argument will be called obj and should contain the instance of the class sending his signal:
my_signal= dispatch.Signal(providing_args=["obj"])
Use cases
UC14-1: add a new Calculation rule (needs to change the openimis.json).
UC14-2: use the frontend contribution to select a calculation rule.
UC14-3: use the fronend contribution to display the parameters required by multiple calculation for an object.
UC14-4: replace a calculation rule.
UC14-5: remove a calculation rule.
Authorities
This module won't have ad-hoc authorities.
Entities
CalculationRules
UUID (char(24) )
CalculationClassName(varchar)
Status (int)
Description (varchar)
Version (int)
Json_ext (json)
DateCreated(date)
DateUpdate(date)
UserUpdateUUID(fk users)
UserCreateUUID (fk users)
DateValidFrom (date)
DateValidTo (date)
Priority (int)
sub table CalculationRulesDetails
UUID (char(24) )
CalculationRulesUUID (varchar)
Status (int)
ClassName
Main (bool)
Params (Json)
ClassParams(json)
Type
rights
Relevance
conditions
Json_ext (json)
DateCreated(date)
DateUpdate(date)
UserUpdateUUID(fk users)
UserCreateUUID (fk users)
Detailed design
Calculations Backend Module
Backend management code
The backend management code will be used to register the calculation sub-module parameters, the sub-module status and the ReadUpdate right management on the database.
This code should have a function to clean the table from the remove calculation
This code should manage the uniqueness of the active version for a given UUID
A Custom signal class be created to add a priority of calculation
from django.dispatch import Signal as BaseSignal from django.dispatch.dispatcher import _make_id class Signal(BaseSignal): def connect(self, receiver, sender=None, weak=True, dispatch_uid=None, priority=50): if dispatch_uid is None: dispatch_uid = _make_id(receiver) inner_uid = '{0}{1}'.format(priority, dispatch_uid) super(Signal, self).connect(receiver, sender=sender, weak=weak, dispatch_uid=inner_uid) self.receivers.sort()
Source of the sub Signal class: https://stackoverflow.com/questions/10017567/possible-to-change-order-of-django-signals
absCalculationRule class
The calculation module will be composed of an abstract class "absCalculation" that will have those methods and members.
This class should be imported as a module in the subclass definition (inside the "hat" modules)
Members
static version
The version is used to keep track of the changes in the version of the calculation rule,
status
integer inactive, future, active, archived
static UUID
UUID to follow the version of the calculation
static CalculationClassName
short name of the calculation rule
static description
description text of the calculation
list of impacted class and parameters
<list>JSONObject objects {class:"className", main:True/False ,'parameters':['type':"int",'name':"example",'rights':{'read':"readAuthority", 'write':"writeAuthority"},relevance:"frontendjsdisplaylogic",condition:"frontendjsvalidationlogic"]} // list of the parameters required on other object,
Methods
ready()
This method makes sure the calculation is registered in the calculation table (if not the line should be added with "inactive status") and register the signals only if it is active
activeForObject(object, context)
this method will contains the checks if the calculation need to be executed for the object on that context. the default context will be:
create
update
delete
submit
amend
replace
check
validate
This function is required because the same class can have different calculation based on the object members values (like product ….)
calculateEvent(sender, **kwargs)
This method runs the calculation based on the object sending the signal, this means that the relationship with the other item required for the calculation could be found from the object sending the signal. (e.g., link to the product can be found in the policy as foreign key.)
This function should call first the activeForObject method, the context will depend on the calling event, if the fuction return true the calcuation needs to be run, in other case the even handling will stop
the calculate(*args) function
Signal need to be set up on the ready function to call it
calculateUUID(*UUID)
Function that fetches the args from the UUID [order specific ?] then run the calculate(*args) function.
calculate(*args)
Function that will do the calculation based on the parameters
getParamteres(ClassName)
Return the data contained on the JSON so the frontend can ask the parameters for a new object of the ClassName.
Calculations Frontend Module
Calculation management page
This page will show the calculation page and change the status/activate a given version
This page should group the calculation by UUID
Contributions
Standard contributions should be available for most of the entities (claims, contribution, contribution collection, policies, insuree ....)
Those contributions should get the parameters template from the backend and display the relevant ones. The values should be saved in the JsonExt fields