works

tools/app/promise-learn/build/index.js

@@ -15,17 +15,21 @@ class DbHandle {
             database: 'heroes'
         });
     }
-    get(stmt) {
+    async getHeroes() {
         var _a, _b;
-        return (_b = (_a = this._conn) === null || _a === void 0 ? void 0 : _a.query(stmt)) !== null && _b !== void 0 ? _b : Promise.reject(new Error('Connection not ready 1'));
+        const result = (_b = await ((_a = this._conn) === null || _a === void 0 ? void 0 : _a.query("SELECT id, name FROM hero"))) !== null && _b !== void 0 ? _b : Promise.reject(new Error('Connection not ready 1'));
+        return result.map((row) => {
+            var _a;
+            return { id: row.id, name: (_a = row.name) !== null && _a !== void 0 ? _a : 'unknown' };
+        });
     }
     close() {
         var _a, _b;
         return (_b = (_a = this._conn) === null || _a === void 0 ? void 0 : _a.end()) !== null && _b !== void 0 ? _b : Promise.reject(new Error('Connection not ready 2'));
     }
 }
-const dbHandle = new DbHandle();
 /*
+const dbHandle = new DbHandle()
 dbHandle.connect()
     .then(() => dbHandle.get("SELECT * FROM hero"))
     .then((result) => {
@@ -34,14 +38,27 @@ dbHandle.connect()
     })
     .catch((err) => {
         console.log(err)
-    }
-    
+    })
 */
+async function exec() {
+    const dbHandle = new DbHandle();
+    try {
+        await dbHandle.connect();
+        const heroes = await dbHandle.getHeroes();
+        console.log(heroes);
+    }
+    finally {
+        await dbHandle.close();
+    }
+}
+exec().catch((err) => console.log(err.message));
+/*
 dbHandle.get("SELECT * FROM hero")
     .then((result) => {
-    console.log(result);
-    return dbHandle.close();
-})
+        console.log(result)
+        return dbHandle.close()
+    })
     .catch((err) => {
-    console.log(err.message);
-});
+        console.log(err.message)
+    })
+*/ 

tools/app/promise-learn/src/index.ts

@@ -1,8 +1,14 @@
 import mariadb from 'mariadb'
+import { stringify } from 'querystring'
 
 let conn : mariadb.Connection
 
 
+interface Hero {
+    id: number
+    name: string
+}
+
 class DbHandle {
     private _conn? : mariadb.Connection
 
@@ -17,8 +23,11 @@ class DbHandle {
         })
     }
 
-    public get(stmt : string) : Promise<any> {
-        return this._conn?.query(stmt) ?? Promise.reject(new Error('Connection not ready 1'))
+    public async getHeroes() : Promise<Hero[]> {
+        const result = await this._conn?.query("SELECT id, name FROM hero") ?? Promise.reject(new Error('Connection not ready 1'))
+        return result.map((row: Record<string, unknown>) => { 
+            return { id: row.id, name: row.name ?? 'unknown' } 
+        })
     }
 
     public close() : Promise<void> {
@@ -43,10 +52,13 @@ dbHandle.connect()
 
 async function exec() : Promise<void> {
     const dbHandle = new DbHandle()
-    await dbHandle.connect()
-    const result = await dbHandle.get("SELECT * FROM hero")
-    console.log(result)
-    await dbHandle.close()
+    try {
+        await dbHandle.connect()
+        const heroes : Hero[] = await dbHandle.getHeroes()
+        console.log(heroes)
+    } finally {
+        await dbHandle.close()
+    }
 }
 
 exec().catch((err) => console.log(err.message))