frustrated by Async events (in javascript BL)

Server Code
1

I’m trying to reproduce second code sample from documentation
https://backendless.com/documentation/business-logic/js/bl_sync_vs_async_code.htm
here is my code:

Backendless.enablePromises();
Backendless.ServerCode.Persistence.afterCreate('tableTwo', function (req, res) {
 var PostsStore = Backendless.Data.of('tableOne');
 return PostsStore.findById('972B0117-12B6-EB2D-FF1E-28171D4C5900')
 .then(post => {
 post.colInt += 1;
 post.colStr = (new Date()).toISOString();
 return PostsStore.save(post);
 })
 .catch(err => {
 return Promise.reject('Unable to save post. Got an error : ' + err.message)
 });
}, true);

and here is my code in client:

Backendless.enablePromises();
Backendless.Persistence.of( 'tableTwo' ).save({colInt:999})
.then(
function(objRet){
 console.log('saved tableTwo ok: ' + JSON.stringify(objRet));
})
.catch(
function(err){
 console.log('saved tableTwo err: ' + JSON.stringify(err));
});

So, when I use async version of afterCreate (with “,true” after function) - I don’t get catch, I always get only “success” function run, even when I have errors (for example if I removed necessary permissions).
Only when I comment out /",true"/ I have working catch()

2

This is a correct behaviour. If you want your handler to have some influence on a new item creation you should make it synchronous. Then it will be able to modify an item before creation, reject creation or perform some other logic. Server will wait for event handler work finish before proceeding with the creation.
If you want just to do some background job like logging, being run in parallel to item creation you should use an async event handler. This way server will not wait for event handler resolution, it will just invoke it and forget about it.

The documentation you mentioned is about something different