Moved to a "cleaner" directory structure

ref #11

src/models/entities/Donation.ts

@@ -0,0 +1,36 @@
+import { PrimaryGeneratedColumn, Column, ManyToOne, Entity, TableInheritance } from "typeorm";
+import {
+  IsInt,
+  IsNotEmpty,
+  IsOptional,
+  IsPositive,
+} from "class-validator";
+import { Participant } from "./Participant";
+
+/**
+ * Defines the donation interface.
+*/
+@Entity()
+@TableInheritance({ column: { name: "type", type: "varchar" } })
+export abstract class Donation {
+  /**
+   * Autogenerated unique id (primary key).
+   */
+  @PrimaryGeneratedColumn()
+  @IsOptional()
+  @IsInt()
+  id: number;
+
+  /**
+   * The donations's donor.
+   */
+  @IsNotEmpty()
+  @ManyToOne(() => Participant, donor => donor.donations, { nullable: true })
+  donor: Participant;
+
+  /**
+   * The donation's amount in cents (or whatever your currency's smallest unit is.).
+   * The exact implementation may differ for each type of donation.
+   */
+  abstract amount: number;
+}