> This is a proposal - not necessarily the end result - to kick off the discussion about the implementation of the new totals utilities
### What
Introduces a BigNumber class implementation, enabling us to work with high-precision numeric values.
**Scope**
- Introduce the BigNumber class
- Remain somewhat backward-compatible (in behavior)
- Establish a foundation for handling high-precision values in more complex scenarios
**Not in scope**
- The implementation will not address complex use cases. However, the concept introduced now should be open for extensibility, so this can be added later without major changes to the calculation logic
### How
There are significant changes to three areas in this PR:
- Schemas
- (De)-Serialization
- Totals calculations
**Schemas**
Domains that need high-precision values will have two DB columns for each value in the database: a standard numeric column and a raw value column.
The standard column is for basic operations like sorting and filtering in the database and is what should be publicly exposed in our API.
The raw value is initially used solely for precise calculations and is stored as a JSONB column. Keeping it as JSONB is flexible and will allow us to extend the concept in future iterations. As of now, the raw value will only require a single property `value`.
**(De)-Serialization**
We cast the raw JSONB value to a `BigNumberRawValue` when reading from the database.
We serialize the standard value to a `BigNumber` when reading from the database.
We use the standard numeric value to construct the raw value upon writing to the database.
For example, the unit price and raw unit price on line items will be inserted as follows:
```ts
@BeforeCreate()
onCreate() {
this.id = generateEntityId(this.id, "cali")
const asBigNumber = new BigNumber(this.raw_unit_price ?? this.unit_price)
this.unit_price = asBigNumber.numeric
this.raw_unit_price = asBigNumber.raw
}
```
**Totals calculations**
For totals calculations, we will use the [`bignumber.js`](https://github.com/MikeMcl/bignumber.js/) library. The library ships with a `BigNumber` class with arithmetic methods for precise calculations.
When we need to perform a calculation, we construct the BigNumber class from the library using the raw value from the database.
Let's have a look at an oversimplified example:
```ts
// create cart with line items
const [createdCart] = await service.create([
{
currency_code: "eur",
items: [
// li_1234
{
title: "test",
quantity: 2,
unit_price: 100,
},
// li_4321
{
title: "test",
quantity: 3,
// raw price creation
unit_price: 200,
},
],
},
])
```
```ts
// calculating line item totals
import BN from "bignumber.js"
const lineItem1 = await service.retrieveLineItem("li_1234")
const lineItem2 = await service.retrieveLineItem("li_4321")
const bnUnitPrice1 = new BN(lineItem1.unit_price.raw)
const bnUnitPrice2 = new BN(lineItem2.unit_price.raw)
const line1Total = bnUnitPrice1.multipliedBy(lineItem1.quantity)
const line2Total = bnUnitPrice2.multipliedBy(lineItem2.quantity)
const total = line1Total.plus(line2Total)
```
**A note on backward compatibility**
Our BigNumber implementation is built to support the existing behavior of numeric values in the database. So even though we serialize the value to a BigNumber, you will still be able to treat it as a standard number, as we've always done.
For example, the following works perfectly fine:
```ts
const lineItem = await service.createLineItem({
title: "test",
quantity: 2,
unit_price: 100,
})
console.log(lineItem.unit_price) // will print `100`
```
However, the type of `unit_price` will be `number | BigNumber`.
**What**
- Remove services that do not have any custom business and replace them with a simple interfaces
- Abstract module service provide the following base implementation
- retrieve
- list
- listAndCount
- delete
- softDelete
- restore
The above methods are created for the main model and also for each other models for which a config is provided
all method such as list, listAndCount, delete, softDelete and restore are pluralized with the model it refers to
**Migration**
- [x] product
- [x] pricing
- [x] promotion
- [x] cart
- [x] auth
- [x] customer
- [x] payment
- [x] Sales channel
- [x] Workflow-*
**Usage**
**Module**
The module service can now extend the ` ModulesSdkUtils.abstractModuleServiceFactory` which returns a class with the default implementation for each method and each model following the standard naming convention mentioned above.
This factory have 3 template arguments being the container, the main model DTO and an object representing the other model with a config object that contains at list the DTO and optionally a singular and plural property in case it needs to be set manually. It looks like the following:
```ts
export default class PricingModuleService</* ... */>
extends ModulesSdkUtils.abstractModuleServiceFactory<
InjectedDependencies,
PricingTypes.PriceSetDTO,
{
Currency: { dto: PricingTypes.CurrencyDTO }
MoneyAmount: { dto: PricingTypes.MoneyAmountDTO }
PriceSetMoneyAmount: { dto: PricingTypes.PriceSetMoneyAmountDTO }
PriceSetMoneyAmountRules: {
dto: PricingTypes.PriceSetMoneyAmountRulesDTO
}
PriceRule: { dto: PricingTypes.PriceRuleDTO }
RuleType: { dto: PricingTypes.RuleTypeDTO }
PriceList: { dto: PricingTypes.PriceListDTO }
PriceListRule: { dto: PricingTypes.PriceListRuleDTO }
}
>(PriceSet, generateMethodForModels, entityNameToLinkableKeysMap)
implements PricingTypes.IPricingModuleService
{
// ...
}
```
In the above, the singular and plural can be inferred as there is no tricky naming. Also, the default implementation does not remove the fact that you need to provides all the overloads etc in your module service interface. The above will provide a default implementation following the interface `AbstractModuleService` which is also auto generated, hence you will have the following methods available:
**for the main model**
- list
- retrieve
- listAndCount
- delete
- softDelete
- restore
**for the other models**
- list**MyModels**
- retrieve**MyModel**
- listAndCount**MyModels**
- delete**MyModels**
- softDelete**MyModels**
- restore**MyModels**
**Internal module service**
The internal module service can now extend `ModulesSdkUtils.internalModuleServiceFactory` which takes only one template argument which is the container type.
All internal services provides a default implementation for all retrieve, list, listAndCount, create, update, delete, softDelete, restore methods which follow the following interface `ModulesSdkTypes.InternalModuleService`:
```ts
export interface InternalModuleService<
TEntity extends {},
TContainer extends object = object
> {
get __container__(): TContainer
retrieve(
idOrObject: string,
config?: FindConfig<any>,
sharedContext?: Context
): Promise<TEntity>
retrieve(
idOrObject: object,
config?: FindConfig<any>,
sharedContext?: Context
): Promise<TEntity>
list(
filters?: FilterQuery<any> | BaseFilterable<FilterQuery<any>>,
config?: FindConfig<any>,
sharedContext?: Context
): Promise<TEntity[]>
listAndCount(
filters?: FilterQuery<any> | BaseFilterable<FilterQuery<any>>,
config?: FindConfig<any>,
sharedContext?: Context
): Promise<[TEntity[], number]>
create(data: any[], sharedContext?: Context): Promise<TEntity[]>
create(data: any, sharedContext?: Context): Promise<TEntity>
update(data: any[], sharedContext?: Context): Promise<TEntity[]>
update(data: any, sharedContext?: Context): Promise<TEntity>
update(
selectorAndData: {
selector: FilterQuery<any> | BaseFilterable<FilterQuery<any>>
data: any
},
sharedContext?: Context
): Promise<TEntity[]>
update(
selectorAndData: {
selector: FilterQuery<any> | BaseFilterable<FilterQuery<any>>
data: any
}[],
sharedContext?: Context
): Promise<TEntity[]>
delete(idOrSelector: string, sharedContext?: Context): Promise<void>
delete(idOrSelector: string[], sharedContext?: Context): Promise<void>
delete(idOrSelector: object, sharedContext?: Context): Promise<void>
delete(idOrSelector: object[], sharedContext?: Context): Promise<void>
delete(
idOrSelector: {
selector: FilterQuery<any> | BaseFilterable<FilterQuery<any>>
},
sharedContext?: Context
): Promise<void>
softDelete(
idsOrFilter: string[] | InternalFilterQuery,
sharedContext?: Context
): Promise<[TEntity[], Record<string, unknown[]>]>
restore(
idsOrFilter: string[] | InternalFilterQuery,
sharedContext?: Context
): Promise<[TEntity[], Record<string, unknown[]>]>
upsert(data: any[], sharedContext?: Context): Promise<TEntity[]>
upsert(data: any, sharedContext?: Context): Promise<TEntity>
}
```
When a service is auto generated you can use that interface to type your class property representing the expected internal service.
**Repositories**
The repositories can now extend `DALUtils.mikroOrmBaseRepositoryFactory` which takes one template argument being the entity or the template entity and provides all the default implementation. If the repository is auto generated you can type it using the `RepositoryService` interface. Here is the new interface typings.
```ts
export interface RepositoryService<T = any> extends BaseRepositoryService<T> {
find(options?: FindOptions<T>, context?: Context): Promise<T[]>
findAndCount(
options?: FindOptions<T>,
context?: Context
): Promise<[T[], number]>
create(data: any[], context?: Context): Promise<T[]>
// Becareful here, if you have a custom internal service, the update data should never be the entity otherwise
// both entity and update will point to the same ref and create issues with mikro orm
update(data: { entity; update }[], context?: Context): Promise<T[]>
delete(
idsOrPKs: FilterQuery<T> & BaseFilterable<FilterQuery<T>>,
context?: Context
): Promise<void>
/**
* Soft delete entities and cascade to related entities if configured.
*
* @param idsOrFilter
* @param context
*
* @returns [T[], Record<string, string[]>] the second value being the map of the entity names and ids that were soft deleted
*/
softDelete(
idsOrFilter: string[] | InternalFilterQuery,
context?: Context
): Promise<[T[], Record<string, unknown[]>]>
restore(
idsOrFilter: string[] | InternalFilterQuery,
context?: Context
): Promise<[T[], Record<string, unknown[]>]>
upsert(data: any[], context?: Context): Promise<T[]>
}
```
