bknd/app/src/data/relations/RelationField.ts

import { type Static, StringEnum, Type } from "core/utils";
import type { EntityManager } from "../entities";
import { Field, type SchemaResponse, baseFieldConfigSchema } from "../fields";
import type { EntityRelation } from "./EntityRelation";
import type { EntityRelationAnchor } from "./EntityRelationAnchor";

const CASCADES = ["cascade", "set null", "set default", "restrict", "no action"] as const;

export const relationFieldConfigSchema = Type.Composite([
   baseFieldConfigSchema,
   Type.Object({
      reference: Type.String(),
      target: Type.String(), // @todo: potentially has to be an instance!
      target_field: Type.Optional(Type.String({ default: "id" })),
      on_delete: Type.Optional(StringEnum(CASCADES, { default: "set null" }))
   })
]);
/*export const relationFieldConfigSchema = baseFieldConfigSchema.extend({
   reference: z.string(),
   target: z.string(),
   target_field: z.string().catch("id"),
});*/

export type RelationFieldConfig = Static<typeof relationFieldConfigSchema>;
export type RelationFieldBaseConfig = { label?: string };

export class RelationField extends Field<RelationFieldConfig> {
   override readonly type = "relation";

   protected getSchema() {
      return relationFieldConfigSchema;
   }

   /*constructor(name: string, config?: Partial<RelationFieldConfig>) {
      //relation_name = relation_name || target.name;
      //const name = [relation_name, target.getPrimaryField().name].join("_");
      super(name, config);

      //console.log(this.config);
      //this.relation.target = target;
      //this.relation.name = relation_name;
   }*/

   static create(
      relation: EntityRelation,
      target: EntityRelationAnchor,
      config?: RelationFieldBaseConfig
   ) {
      const name = [
         target.reference ?? target.entity.name,
         target.entity.getPrimaryField().name
      ].join("_");
      //console.log('name', name);
      return new RelationField(name, {
         ...config,
         required: relation.required,
         reference: target.reference,
         target: target.entity.name,
         target_field: target.entity.getPrimaryField().name
      });
   }

   reference() {
      return this.config.reference;
   }

   target() {
      return this.config.target;
   }

   targetField(): string {
      return this.config.target_field!;
   }

   override schema(): SchemaResponse {
      return this.useSchemaHelper("integer", (col) => {
         //col.references('person.id').onDelete('cascade').notNull()
         // @todo: implement cascading?

         return col
            .references(`${this.config.target}.${this.config.target_field}`)
            .onDelete(this.config.on_delete ?? "set null");
      });
   }

   override transformRetrieve(value: any): any {
      return value;
   }

   override async transformPersist(value: any, em: EntityManager<any>): Promise<any> {
      throw new Error("This function should not be called");
   }

   override toJsonSchema() {
      return this.toSchemaWrapIfRequired(
         Type.Number({
            $ref: `${this.config?.target}#/properties/${this.config?.target_field}`
         })
      );
   }
}