Implemented fixed donation updateing

ref #66

src/models/actions/update/UpdateDonation.ts

@@ -0,0 +1,41 @@
+import { IsInt, IsPositive } from 'class-validator';
+import { getConnection } from 'typeorm';
+import { DonorNotFoundError } from '../../../errors/DonorErrors';
+import { Donation } from '../../entities/Donation';
+import { Donor } from '../../entities/Donor';
+
+/**
+ * This class is used to update a Donation entity (via put request).
+ */
+export abstract class UpdateDonation {
+    /**
+     * The updated donation's id.
+     * This shouldn't have changed but it is here in case anyone ever wants to enable id changes (whyever they would want to).
+     */
+    @IsInt()
+    id: number;
+
+    /**
+     * The updated donation's associated donor.
+     * This is important to link donations to donors.
+     */
+    @IsInt()
+    @IsPositive()
+    donor: number;
+
+    /**
+     * Creates a new Donation entity from this.
+     */
+    public abstract update(donation: Donation): Promise<Donation>;
+
+    /**
+     * Gets a donor based on the donor id provided via this.donor.
+     */
+    public async getDonor(): Promise<Donor> {
+        const donor = await getConnection().getRepository(Donor).findOne({ id: this.donor });
+        if (!donor) {
+            throw new DonorNotFoundError();
+        }
+        return donor;
+    }
+}