Create nested Transaction in mssql using NodeJS - node.js

Question

I am trying to create nested transactions in NodeJs using MSSQL NPM. I am using following code block
var sqlModule = require("mssql");
var sqlManagerClass = require("./sqlManager.js");
var sql = new sqlManagerClass(sqlModule);
sql.setConfig({
user: "dbo",
password: "***********",
server: "127.0.0.1",
database: "dbname",
requestTimeout: 120000,
});
sql.beginTransaction(function (transaction) {
if (transaction == null) {
callback("Unable to Start Transaction", null);
return;
}
sql.beginTransaction(function (newTransaction) {
if (newTransaction == null) {
callback("Unable to Start newTransaction", null);
return;
}
sql.execute(
"dbname.dbo.insert_dest",
[],
[],
function (err, results) {
console.log(results);
newTransaction.commit(function (err) {
if (err) {
console.log(err);
}
sql.execute("dbname.dbo.select_dest", [], [], function (
err,
results2
) {
if (err) {
console.log(err);
return;
}
console.log(results2);
transaction.rollback(function (rollBackErr) {
if (rollBackErr) {
console.log(rollBackErr);
}
sql.execute("dbname.dbo.select_dest", [], [], function (
err,
results2
) {
if (err) {
console.log(err);
return;
}
console.log(results2);
console.log('end')
});
});
});
});
},
newTransaction
);
});
});
creating transaction
this.beginTransaction = function(callback, transaction) {
// if the optional transaction argument is passed in, we are already working with a transation, just return it
if (typeof transaction !== "undefined") {
callback(transaction);
return;
}
self.connectSql(function(err) {
var transaction = new self.sql.Transaction(self.connection);
transaction.begin(function(err) {
// ... error checks
if (err) {
self.log("SQLManager - Error Beginning Transaction " + err);
callback(null);
}
// callback with the transaction handler
callback(transaction);
});
});
}
I have to create 2 transactions so that I can start a transaction and perform a set of operations on different stored procedures id any thing goes wrong I can revert back to my original state using the first transaction.
In short I am trying to achieve something like following SQL code
BEGIN TRAN T1;
BEGIN TRAN M2
INSERT INTO dbo.dest
(
Code,
Text,
Type
)
VALUES
( 'l', -- Code - varchar(50)
'Love', -- Text - varchar(50)
2 -- Type - int
)
COMMIT TRAN M2
// I am calling another Sp which is similar to this
SELECT * FROM dbo.dest
//validation the code
//if error
ROLLBACK TRAN T1
My question is how can I create nested transaction so that I can revert back entire transaction if any error occur after the first transaction complete. Thank you.

Answer 1

First read this
A SQL Server DBA myth a day: (26/30) nested transactions are real
To see if SQL Server "nested transactions" or savepoints are really going to help you.
Then you'll probably have to handle this all yourself by issuing the transaction control statements using sql.execute() eg:
sql.execute("begin transaction");
//something that works
sql.execute("save transaction MyTran");
//something that fails
sql.execute("rollback transaction MyTran");
sql.execute("commit transaction");
how can I create nested transaction so that I can revert back entire transaction if any error occur after the first transaction complete
What you have will do that. Nested transactions are not real, so calling
begin tran
...
begin tran --<-- ##trancount += 1, but nothing else really happens
...
commit tran --<--nothing is really commited yet. ##trancount -= 1
...
rollback tran --<-- all work is rolled back