be even more safe in db

lib/wallet/query.ts

@@ -34,7 +34,7 @@ export class Store<T> {
   }
 }
 
-export class Index<S,T> {
+export class Index<S extends IDBValidKey,T> {
   indexName: string;
   storeName: string;
 
@@ -49,7 +49,7 @@ export class Index<S,T> {
  * with indices.
  */
 export interface QueryStream<T> {
-  indexJoin<S,I>(index: Index<I,S>,
+  indexJoin<S,I extends IDBValidKey>(index: Index<I,S>,
                  keyFn: (obj: T) => I): QueryStream<[T, S]>;
   filter(f: (x: any) => boolean): QueryStream<T>;
   reduce<S>(f: (v: T, acc: S) => S, start?: S): Promise<S>;
@@ -92,7 +92,7 @@ abstract class QueryStreamBase<T> implements QueryStream<T> {
     return new QueryStreamFlatMap(this, f);
   }
 
-  indexJoin<S,I>(index: Index<I,S>,
+  indexJoin<S,I extends IDBValidKey>(index: Index<I,S>,
                  keyFn: (obj: T) => I): QueryStream<[T, S]> {
     this.root.addStoreAccess(index.storeName, false);
     return new QueryStreamIndexJoin(this, index.storeName, index.indexName, keyFn);
@@ -301,7 +301,7 @@ export class QueryRoot {
     return new IterQueryStream(this, store.name, {});
   }
 
-  iterIndex<S,T>(index: Index<S,T>, only?: S): QueryStream<T> {
+  iterIndex<S extends IDBValidKey,T>(index: Index<S,T>, only?: S): QueryStream<T> {
     this.stores.add(index.storeName);
     return new IterQueryStream(this, index.storeName, {
       only,
@@ -377,7 +377,7 @@ export class QueryRoot {
   /**
    * Get one object from a store by its key.
    */
-  getIndexed(storeName: string, indexName: string, key: any): Promise<any> {
+  getIndexed<I extends IDBValidKey,T>(index: Index<I,T>, key: I): Promise<T|undefined> {
     if (key === void 0) {
       throw Error("key must not be undefined");
     }
@@ -385,13 +385,13 @@ export class QueryRoot {
     const {resolve, promise} = openPromise();
 
     const doGetIndexed = (tx: IDBTransaction) => {
-      const req = tx.objectStore(storeName).index(indexName).get(key);
+      const req = tx.objectStore(index.storeName).index(index.indexName).get(key);
       req.onsuccess = () => {
         resolve(req.result);
       };
     };
 
-    this.addWork(doGetIndexed, storeName, false);
+    this.addWork(doGetIndexed, index.storeName, false);
     return Promise.resolve()
                   .then(() => this.finish())
                   .then(() => promise);

lib/wallet/wallet.ts

@@ -329,9 +329,17 @@ namespace Stores {
     timestampIndex = new Index<number,HistoryRecord>(this, "timestamp");
   }
 
+  class TransactionsStore extends Store<Transaction> {
+    constructor() {
+      super("transactions");
+    }
+
+    repurchaseIndex = new Index<[string,string],Transaction>(this, "repurchase");
+  }
+
 
   export let exchanges: ExchangeStore = new ExchangeStore();
-  export let transactions: Store<Transaction> = new Store<Transaction>("transactions");
+  export let transactions: TransactionsStore = new TransactionsStore();
   export let reserves: Store<ReserveRecord> = new Store<ReserveRecord>("reserves");
   export let coins: CoinsStore = new CoinsStore();
   export let refresh: Store<RefreshSession> = new Store<RefreshSession>("refresh");
@@ -1444,10 +1452,9 @@ export class Wallet {
       console.log("no repurchase: no correlation id");
       return {isRepurchase: false};
     }
-    let result: Transaction = await (
+    let result: Transaction|undefined = await (
       this.q()
-          .getIndexed("transactions",
-                      "repurchase",
+          .getIndexed(Stores.transactions.repurchaseIndex,
                       [
                         contract.merchant_pub,
                         contract.repurchase_correlation_id