节点JS Promise TypeError：无法读取未定义的属性'then'

Question

我在控制器文件上出现错误。 TypeError：无法读取未定义的属性“ then”

我的模型文件包含

        function dbQuerynew(sql){
            return new Promise( ( resolve, reject ) => {
                db.query(sql,
                 (err, result) => {
                   if (err) {
                     return reject(err)
                   }
                   return resolve(result)
                });
              })
        }
    var Product = {
        checkIds: function(product_id){
                var id_exist = 0;
                var sql = "SELECT mid FROM table WHERE product_id = '" + product_id + "'";
                const results = dbQuerynew(sql)
                .then(results => {
                    Promise.all(results.map(myId =>{
                        if(myId.mid === 46){
                             id_exist = 1;
                        }
                    }))
                })
                .then(()=>{
                     return id_exist;
                });
            }
    }

我的控制器文件包含

    exports.checkIdsFromProducts = (request,response) => {
        let getData = request.body;
        var product_id = getData.product_id
            product.checkIds(product_id)
            .then(result => {
                console.log(result);
            })
    }