Add external order id query for paypal and klarna ids (#80)

src/datasources/order-api.ts

@@ -102,6 +102,24 @@ export class OrderAPI extends BaseSQLDataSource {
       .then((row) => this.createOrderFromRow(row));
   }
 
+  async getOrderByExternalId(
+    klarnaOrderId: string,
+    paypalTransactionId: string,
+  ): Promise<Order> {
+    const column = paypalTransactionId
+      ? 'paypal_transaction_id'
+      : 'klarna_order_id';
+    const value = paypalTransactionId ?? klarnaOrderId;
+
+    return this.knex
+      .select('*')
+      .from('orders')
+      .where(column, value)
+      .first()
+      .cache(MINUTE)
+      .then((row) => this.createOrderFromRow(row));
+  }
+
   async getOrderRowFieldMapping(): Promise<any> {
     // const fields = await this.knex.select('*').from('order-row_fields'); doesn't work becuase of string case...
     const fieldsRes = await this.cachedRaw('SELECT * from "order-row_fields"')