refactor(core): Use mixins to delete redundant code between Entity classes (no-changelog) (#6616)

* db entities don't need an ID before they are inserted

* don't define constructors on entity classes, use repository.create instead

* use mixins to reduce duplicate code in db entity classes

packages/cli/src/databases/entities/AbstractEntity.ts

@@ -1,6 +1,13 @@
-import { BeforeUpdate, CreateDateColumn, UpdateDateColumn } from 'typeorm';
+import {
+	BeforeInsert,
+	BeforeUpdate,
+	CreateDateColumn,
+	PrimaryColumn,
+	UpdateDateColumn,
+} from 'typeorm';
 import { IsDate, IsOptional } from 'class-validator';
 import config from '@/config';
+import { generateNanoId } from '../utils/generators';
 
 const dbType = config.getEnv('database.type');
 
@@ -14,26 +21,53 @@ const timestampSyntax = {
 export const jsonColumnType = dbType === 'sqlite' ? 'simple-json' : 'json';
 export const datetimeColumnType = dbType === 'postgresdb' ? 'timestamptz' : 'datetime';
 
-export abstract class AbstractEntity {
-	@CreateDateColumn({
-		precision: 3,
-		default: () => timestampSyntax,
-	})
-	@IsOptional() // ignored by validation because set at DB level
-	@IsDate()
-	createdAt: Date;
+const tsColumnOptions = {
+	precision: 3,
+	default: () => timestampSyntax,
+};
 
-	@UpdateDateColumn({
-		precision: 3,
-		default: () => timestampSyntax,
-		onUpdate: timestampSyntax,
-	})
-	@IsOptional() // ignored by validation because set at DB level
-	@IsDate()
-	updatedAt: Date;
+type Constructor<T> = new (...args: any[]) => T;
 
-	@BeforeUpdate()
-	setUpdateDate(): void {
-		this.updatedAt = new Date();
+function mixinStringId<T extends Constructor<{}>>(base: T) {
+	class Derived extends base {
+		@PrimaryColumn('varchar')
+		id: string;
+
+		@BeforeInsert()
+		generateId() {
+			if (!this.id) {
+				this.id = generateNanoId();
+			}
+		}
 	}
+	return Derived;
 }
+
+function mixinTimestamps<T extends Constructor<{}>>(base: T) {
+	class Derived extends base {
+		@CreateDateColumn(tsColumnOptions)
+		@IsOptional() // ignored by validation because set at DB level
+		@IsDate()
+		createdAt: Date;
+
+		@UpdateDateColumn({
+			...tsColumnOptions,
+			onUpdate: timestampSyntax,
+		})
+		@IsOptional() // ignored by validation because set at DB level
+		@IsDate()
+		updatedAt: Date;
+
+		@BeforeUpdate()
+		setUpdateDate(): void {
+			this.updatedAt = new Date();
+		}
+	}
+	return Derived;
+}
+
+class BaseEntity {}
+/* eslint-disable @typescript-eslint/naming-convention */
+export const WithStringId = mixinStringId(BaseEntity);
+export const WithTimestamps = mixinTimestamps(BaseEntity);
+export const WithTimestampsAndStringId = mixinStringId(WithTimestamps);