Question

我正在尝试从节点功能查询sqlite3。根据结果，它应该返回TRUE或FALSE回到调用代码。这就是我所做的，但总是得到'未定义'：

var sqlite3 = require("sqlite3").verbose();


var dbOpen = function dbOpen() {
    sqlite3 = require('sqlite3').verbose();
    db = new sqlite3.Database('./internaldb/OPMSE.db');
}
module.exports.dbOpen = dbOpen;
dbOpen();
mKey = 'AIzaSyCrIYuHJ_jiZqmGYoAs7mxiloB3-OBx5WI';
async function db1() {
    function db2() {
        db.each("SELECT STATUS status FROM API_Keys WHERE KEY = ? AND STATUS = ?", [mKey, '1'], (err, row, x) => {
            var keyValid = false;
            if (err) {
                console.log('There is an error in API Validation')
            } else {
                console.log(keyValid + '<--This is from upper fun')
                keyValid = true;
                return keyValid;
            }
            db.close();
            return keyValid;
        });
    } // db2 
    d = await db2();
    console.log(d + '<--Supposed to return TRUE or FALSE')
} //db1

x = db1();
console.log(x)
/*Returns:
Promise { <pending> }
undefined<--Supposed to return TRUE or FALSE
false<--This is from upper fun
*/

Answer 1

如果你让db2返回一个promise它会起作用，如果你想知道密钥是否在数据库中，最好select count它会返回一条记录并且你不会忘记密码。需要db.each（不确定获取一条记录的方法）。

以下是包含一些注释的代码，这应该可行：

var sqlite3 = require("sqlite3").verbose();


var dbOpen = function dbOpen() {
  sqlite3 = require('sqlite3').verbose();
  db = new sqlite3.Database('./internaldb/OPMSE.db');
}
module.exports.dbOpen = dbOpen;
dbOpen();
mKey = 'AIzaSyCrIYuHJ_jiZqmGYoAs7mxiloB3-OBx5WI';
async function db1() {
  function db2() {
    //return a promise
    return new Promise(
      (resolve,reject)=>
        db.serialize(
          function() {
            var keyValid = false;
            db.each(//maybe not use each but just get one record and select count(*)
              "SELECT STATUS status FROM API_Keys WHERE KEY = ? AND STATUS = ?",
              [mKey, '1'], (err, row, x) => {
                if (err) {
                  reject(err);//reject on error
                } else {
                  console.log(keyValid + '<--This is from upper fun');
                  keyValid = true;
                }
              }
            );
            db.colose();
          }
        )
      )
  } // db2 
  d = await db2();
  console.log(d + '<--Supposed to return TRUE or FALSE')
} //db1

x = db1();
console.log(x)

查询sqlite3后，Node.js返回true或false

1 个答案: