How do you make multiple database calls from a single connection/transaction with Node.js and Tedious

Question

I am attempting to use NodeJS with the Tedious (http://pekim.github.io/tedious/) sql server plugin to make multiple database calls. My intent is to: 1. Open a connection 2. Start a transaction 3. Make multiple database (stored procedure) calls, which will not return any data. 4. Commit transaction (or roll back on error). 5. Close connection

Here is an example .js file, (without using a transaction) for NodeJS where I am attempting to make multiple database calls and it is failing with the error "Requests can only be made in the LoggedIn state, not the SentClientRequest state." Nothing I try resolves this issue.

Does anyone know how to resolve this?

var Connection = require('tedious').Connection;
var Request = require('tedious').Request;

var config = {
    userName: 'login',
    password: 'password',
    server: '127.0.0.1',
    options: { rowCollectionOnDone: true }
};

var max = 1;
for (var i = 0; i < max; i++) {
    var connection = new Connection(config);

    function executeStatement() {
        request = new Request("select 42, 'hello world'", function (err, rowCount) {
            if (err) {
                console.log(err);
            } else {
                console.log(rowCount + ' rows');
            }
        });

        request.on('row', function (columns) {
            columns.forEach(function (column) {
                console.log(column.value);
            });
        });

        request.on('doneInProc', function (rowCount, more, rows) {
        });

        request.on('doneProc', function (rowCount, more, rows) {
            console.log('statement completed!')
            connection.execSql(request);
        });

        request.on('returnStatus', function (status) {
            console.log('statement completed!')
        });

        connection.execSql(request);
    }

    connection.on('connect', function (err) {
        // If no error, then good to go...
        executeStatement();
    });
}
console.log('Done!');

Answer 1

You're trying to execute a statement on a connection that is not established. You're missing an error handler before you call executeStatement.

connection.on('connect', function (err) {
    if (err) {
        console.log(err); // replace with your code
        return;
    };

    // If no error, then good to go...
    executeStatement();
});

Edit:

How to execute multiple statements in a transaction in serial:

var statements = ["select 1", "select 2", "select 3"];

var transaction = new sql.Transaction(connection);
transaction.begin(function(err) {
    // ... error checks

    async.mapSeries(statements, function(statement, next) {
        var request = new sql.Request(transaction);
        request.query(statement, next);
    }, function(err, results) {
        // ... error checks

        transaction.commit(function(err, recordset) {
            // ... error checks

            console.log("Transaction commited.");
        });
    });
});