Verify successful write-transaction

[jariwals]

After running the Cypher query to create a new node if it doesn't exist using MERGE clause, I want to check if the write-transaction is successful.
How do I do that? Perhaps a status or code?
I'm getting following as result from the tx.run statement -

Preformatted textResult {
  _stack:
   '\n    at captureStacktrace (   at new Promise (<anonymous>)',
  _streamObserver:
   _TransactionStreamObserver {
     _fieldKeys: null,
     _fieldLookup: null,
     _queuedRecords: [],
     _tail: null,
     _error: null,
     _hasFailed: false,
     _observer: null,
     _conn: null,
     _meta: {},
     _tx:
      Transaction {
        _connectionHolder: [ConnectionHolder],
        _state: [Object],
        _onClose: [Function: bound _transactionClosed],
        _onBookmark: [Function: bound _updateBookmark] } },
  _p: null,
  _statement: 'match (u:user{firstName: \'abc\'}) return u',
  _parameters: {},
  _metaSupplier: [Function],
  _connectionHolder:
   EmptyConnectionHolder {
     _mode: undefined,
     _connectionProvider: undefined,
     _referenceCount: 0,
     _connectionPromise: Promise { null } } }

Thank you!

[jsmccrumb]

It looks like your statement there is 'match (u:user{firstName: \'abc\'}) return u' -- so not a merge?

But to check the result (without returning anything), you'll know it is successful if it does not error.

var session = driver.session();
session.writeTransaction(function(tx) {
  tx.run('MERGE (u:User {name: "Bob"})').then(function(result) {
    console.log('No Error! It Worked!', result.summary.counters.nodesCreated());
  }).catch(function(error) {
    console.error('Query failed!', error);
  }).finally(function() {
    session.close();
  })
});

I may have misunderstood your question? Feel free to clarify!

[jariwals]

Thank you for your prompt response, Jacob.
You're right. Unfortunately, the dump was from a the MATCH clause instead of MERGE clause.
My code with MERGE clause is -

session.writeTransaction(function (transaction) {
        transaction.run("merge (u:user{firstName:'" + firstName + "', lastName:'" + lastName + "', email:'" + email + "', githubUrl: '" + githubUrl + "', linkedinUrl:'" + linkedinUrl + "'}) return u");
        // var result = transaction.run("match (u:user{firstName: '" + firstName + "'}) return u");
    }).then(result => {
        console.log("nodes created: ", result.summary.counters.nodesCreated());
    }).catch(error => {
        console.log('error: ', error)
    }).finally(()=>{
        session.close();
        return res.json({ result });
    });

However I'm getting error for summary being undefined. Stack-trace from the error is as given below.
Note that the required node is being added though.

result:  Result {
  _stack:
   '\n    at captureStacktrace (  at new Promise (<anonymous>)',
  _streamObserver:
   _TransactionStreamObserver {
     _fieldKeys: null,
     _fieldLookup: null,
     _queuedRecords: [],
     _tail: null,
     _error: null,
     _hasFailed: false,
     _observer: null,
     _conn: null,
     _meta: {},
     _tx:
      Transaction {
        _connectionHolder: [ConnectionHolder],
        _state: [Object],
        _onClose: [Function: bound _transactionClosed],
        _onBookmark: [Function: bound _updateBookmark] } },
  _p: null,
  _statement:
   'merge (u:user{firstName:\'abc\', lastName:\'dlisnc\', email:\'dvkdsnf\', githubUrl: \'fhsdiukn\', linkedinUrl:\'fsidnfk\'}) return u',
  _parameters: {},
  _metaSupplier: [Function],
  _connectionHolder:
   EmptyConnectionHolder {
     _mode: undefined,
     _connectionProvider: undefined,
     _referenceCount: 0,
     _connectionPromise: Promise { null } } }
error:  TypeError: Cannot read property 'summary' of undefined
    at session.writeTransaction.then.result (web-app\server\server.js:69:47)   
    at process._tickCallback (internal/process/next_tick.js:68:7)
(node:20316) UnhandledPromiseRejectionWarning: ReferenceError: result is not defined
    at session.writeTransaction.then.catch.finally (web-app\server\server.js:74:27)
    at <anonymous>
    at process._tickCallback (internal/process/next_tick.js:68:7)
(node:20316) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a 
promise which was not handled with .catch(). (rejection id: 1)
(node:20316) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
result:  Result {
  _stack:
   '\n    at captureStacktrace  at new Promise (<anonymous>)',
  _streamObserver:
    at <anonymous>
    at process._tickCallback (internal/process/next_tick.js:68:7)
(node:19988) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a 
promise which was not handled with .catch(). (rejection id: 1)
(node:19988) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
------------------------------
error:  TypeError: Cannot read property 'summary' of undefined
    at session.writeTransaction.then.result (web-app\server\server.js:69:47)   
    at process._tickCallback (internal/process/next_tick.js:68:7)
(node:19988) UnhandledPromiseRejectionWarning: ReferenceError: result is not defined
    at session.writeTransaction.then.catch.finally (web-app\server\server.js:74:27)
    at <anonymous>
    at process._tickCallback (internal/process/next_tick.js:68:7)
(node:19988) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a 
promise which was not handled with .catch(). (rejection id: 2)

Am I missing something here?

[jsmccrumb]

Ah I see, looks like you just need to add

return

To line with tx . Run. That should do it, as it stands it is not returning anything so promise resolved to undefined or null.

[jariwals]

That worked!
Thanks a lot, Jacob!