Node.js上的SQLite：重载数据库

Question

I got a Problem with connecting to a database from two different functions in node.js.

At first, i connect to the SQLite DB to read some data out of it:

function getRbls(linie, stop) {
return new Promise(function (resolve, reject) {

    var db = openDB();

    var sql = someSQLString;

    db.all(sql, function (err, rows) {
        if (err) reject(err);
        var rbls = [];

        if (rows != null) {
            for (var i = 0; i < rows.length; i++) {
                rbls.push(rows[i].rbl)

            }
            console.log("RBLs: " + rbls);

        } else {
            rbls = false;
        }
        resolve(rbls);
    });
    db.close();

});

This code works just fine and I had it running for a while now.

Now I wanted to implement a second function which always runs AFTER the first one is finished. To save some data in a different table:

function saveLastMonitorCall(rbls,userID) {
    var db = openDB();

//Has User a last call saved?
db.get(CountUserSQL,
    function (err, userCount) {
        if (err) throw err;

        var rblsString = rbls.toString();

        if (userCount > 0) {
            //User has a call in DB
            db.run(UpdateUserSQL,
                function (err) {
                    if (err) throw err;
                    console.log("User " + userID + " updated");
                }
            );

        } else {
            //User is new to DB
            db.run(InserNewUserSQL,
                function (err) {
                    if (err) throw err;
                    console.log("New User saved");
                }
            );
        }
    }
);

The odd thing is that in the second function I get the error message on the first db.get :

SQLITE_CANTOPEN: unable to open database file at Error (native)

The function openDB(); has the following code which works fine for the first function:

function openDB() {
if (db) {
    return db;
} else {
    var sqlite = require('sqlite3');
    db = new sqlite.Database('./SQLite/StammdatenDB.db', function (err) {
        if (err) {
            //console.log(err);
            throw(err);
        }
        console.log("Connected to DB");

    });
    return db;
}
}

Anyone has a clue what the error could be?

Thanks in advance!

Answer 1

You store the reference to the db in the db global variable (that's what I'm getting from the first lines of openDB ), but then you call db.close() in the first function, not clearing the db reference.

Since this is SQLite and you are closing the connection immediately I'd drop the first part of the conditional in openDB and only leave what you have in the else block.