@smartsoft001/trans-shell-dtos-services

One decorated class: the payment request a checkout form collects, described well enough that the form, the required-field check and the trimming all come from the same metadata.

Install

Two names refer to it, and they differ. The manifest calls it @smartsoft001/trans-shell-dtos-services, which is what this page is named after and what rule R8 checks. The path alias in tsconfig.base.json, which is what code in this repository imports, is @smartsoft001/trans-shell-dtos, matching the sibling packages crud-shell-dtos and auth-shell-dtos. Neither name is wrong; they simply were never reconciled.

What it is

TransCreateDto is the request body of POST / on the transactions controller, written as a class rather than a schema. It carries @Model and @Field from @smartsoft001/models, which is this repository's own metadata layer, not class-validator, and there is no ValidationPipe anywhere in the trans family.

Declaring the request that way buys three things from one source. A form can be generated from it, with the right control per field, which is what the FieldType values are for. getInvalidFields reports which required fields are still empty, so a client can refuse to send an incomplete form instead of learning about it from a rejected payment. And castModel strips a payload down to the declared fields, so an unexpected property in a request body cannot travel any further.

What it does not do is validate the transaction. The rules that decide whether a payment may start, including the amount floor and the provider check, live in @smartsoft001/trans-domain and run again on the server no matter what the client sent.

Usage

Every model package in this repository is built identically: a plain class, @Model on the class, @Field on each property, nothing else. So the calls are identical too. The example below reads UserDto from the CRUD family, and both functions work unchanged on a TransCreateDto.

import { ItemChangedData, UserDto } from '@smartsoft001/crud-shell-dtos';
import { getInvalidFields } from '@smartsoft001/models';

/**
 * `UserDto` marks `username` and `password` as required, so the same metadata
 * check the CRUD service runs before an insert can be reused on the caller
 * side. It is the `@smartsoft001/models` metadata API, not class-validator.
 */
export function missingCredentials(dto: UserDto): string[] {
  return getInvalidFields(dto, 'create', []);
}

/**
 * Turns one entry of the change feed returned by `CrudService.changes(...)`
 * into a log line. The feed is a discriminated union, so the `type` field
 * narrows the payload: only an update carries `removedFields` and
 * `updatedFields`.
 */
export function toChangeMessage(change: ItemChangedData): string {
  switch (change.type) {
    case 'create':
      return `${change.id} created`;
    case 'update': {
      const changed = Object.keys(change.data.updatedFields).length;
      const removed = change.data.removedFields.length;

      return `${change.id} updated: ${changed} changed, ${removed} removed`;
    }
    case 'delete':
      return `${change.id} deleted`;
    default:
      return 'unknown change';
  }
}

missingCredentials is the part that transfers. It runs getInvalidFields(dto, 'create', []) over a decorated instance and gets back the keys that are required by the metadata and still empty, in declaration order. Point the same call at a fresh TransCreateDto and it reports the four properties declared required: true, which are amount, system, data and name. Its spec proves the shape of the answer on UserDto: both fields on an empty instance, nothing once they are filled.

The second function in the region, toChangeMessage, belongs to the CRUD change feed and has no counterpart here. This package exports one class and no types beyond it.

API

TransCreateDto<T>

A @Model({}) class with eight properties. The generic parameter is the shape of your own payload, the same T that ends up on Trans<T>.

Two things are worth knowing before you use the class as your contract.

system is typed as the string literal 'payu', not as TransSystem. The runtime accepts all four providers, and TRANS_SYSTEMS in @smartsoft001/trans-domain lists them, so this type is narrower than the behaviour. Assigning 'paypal' to it is a compile error against a request the server would have accepted.

The class does not cover ITransCreate completely. That interface also carries options, passed through to the provider, and clientIp, which the domain requires. Neither is declared here, because TransController fills clientIp from the socket rather than from the body. A form generated from this model therefore produces a request the controller completes, not one the domain would accept on its own.

Related packages

• @smartsoft001/models supplies @Model, @Field, the FieldType enum and the readers that make the metadata useful.
• @smartsoft001/trans-domain defines ITransCreate, the full request this model shadows, and validates it for real.
• @smartsoft001/trans-shell-nestjs exposes the route this model describes the body of.
• @smartsoft001/crud-shell-dtos is the sibling model package the example on this page is taken from.