Implemented fixed donation updateing

ref #66

src/models/actions/update/UpdateFixedDonation.ts

@@ -0,0 +1,27 @@
+import { IsInt, IsPositive } from 'class-validator';
+import { FixedDonation } from '../../entities/FixedDonation';
+import { UpdateDonation } from './UpdateDonation';
+
+/**
+ * This class is used to update a FixedDonation entity (via put request).
+ */
+export class UpdateFixedDonation extends UpdateDonation {
+    /**
+     * The updated donation's amount.
+     * The unit is your currency's smallest unit (default: euro cent).
+     */
+    @IsInt()
+    @IsPositive()
+    amount: number;
+
+    /**
+     * Update a FixedDonation entity based on this.
+     * @param donation The donation that shall be updated.
+     */
+    public async update(donation: FixedDonation): Promise<FixedDonation> {
+        donation.amount = this.amount;
+        donation.donor = await this.getDonor();
+
+        return donation;
+    }
+}