Problems with Transaction API in CloudCode

Server Code
1

Dear Backendless team,
I’m trying to build a custom event handler that would use the Backendless V6 transaction feature. I ran into a couple of problems.

Backendless Version (3.x / 5.x, Online / Managed / Pro )

6.0.4

Application ID

3B8C2D2E-B7D6-27F9-FF3F-ABEE20934E00

Description

  1. The addRelation API seems not working. When I called unitOfWork.addRelation in event handler code, it keeps throwing missing ) after argument list error.

  2. For some API that didn’t throw error, when the code is running in cloud, it will gives Backendless.UnitOfWork() is not a constructor error. I copied the exact same code from document. const unitOfWork = new Backendless.UnitOfWork();.

2

Hello,

Do you use JS or Java?

Could you please show how you invoke the addRelation call?

Regards,
Mark

3

Hi Mark,

I’m using JS. My code is quite basic. Just like this:

Backendless.ServerCode.customEvent('sendFollow', function(req) {
	var senderId = req.args["senderId"]
	var receiverId = req.args["receiverId"]
	Backendless.Data.of( "Users" ).findById( {objectId:receiverId } )
	 .then( function( user ) {
	 	const unitOfWork = new Backendless.UnitOfWork();
    	unitOfWork.addRelation(	tableName: "Users",
    							parentObjectId: senderId,
    							columnName: "followingPending",
    							childrenObjectId: [receiverId] )
	    unitOfWork.execute()
		.then( function( unitOfWorkResult ) {
			console.log("transaction completed")
		 })
		.catch( function( error ) {
			console.log("something wrong with the transaction")
		 });
	  })
	 .catch( function( error ) {
 		console.log("findby Failed")
 		console.log(error)
	  });
});

When I run npm run debug, the code throws missing ) after argument list error.
Thanks!

4

Hi Evan,

Make sure to change the name of the method to addToRelation. I think it is the culprit of the errors. I will make sure the docs are updated as well to reflect this.

Regards,
Mark

5

Hi Mark,

Thanks for your reply. Unfortunately, on my end, using addToRelation isn’t changing anything. The error remains. Still missing ) after argument list.

Evan

6

Hi Evan,

I do not see anything wrong with your code. It must be something within the SDK.

@stanislaw.grin, could you please take a look?

Regards
Mark

7

Hi @Evan_Cui,

missing ) after argument list error is a JS syntax error because you’re passing neither object nor the simple arguments list in the ‘addRelation’ method.

Here is how it should be:

unitOfWork.addRelation('Users', senderId, 'followingPending',[receiverId])

Also, there’re no addRelation method - but there is addToRelation.
So, your code should look next way:

Backendless.ServerCode.customEvent('sendFollow', function(req) {
  const senderId = req.args['senderId']
  const receiverId = req.args['receiverId']

  Backendless.Data.of('Users').findById({ objectId: receiverId })
    .then(function(user) {
      const unitOfWork = new Backendless.UnitOfWork()
      
      unitOfWork.addToRelation('Users', senderId, 'followingPending', [receiverId])
      
      unitOfWork.execute()
        .then(function(unitOfWorkResult) {
          console.log('transaction completed')
        })
        .catch(function(error) {
          console.log('something wrong with the transaction')
        })
    })
    .catch(function(error) {
      console.log('findby Failed')
      console.log(error)
    })
})

Regards,
Stanislaw

8

Hi @stanislaw.grin ,

Thank you for your reply. You are right, the new function call doesn’t throw any error now when I run npm run debug.

However, it still causes the second problem as I described in the description at the beginning. When this event handler receives any requests, it throws TypeError: Backendless.UnitOfWork is not a constructor. I copied the exact same code as you posted here. Is there any problem with the way I initialize the unitOfWork instance?

Thanks!
Evan

9

Hi Evan,

Could you try updating your local installation of Coderunner? I suspect running npm i should do the trick.

Regards,
Mark

10

Hi @mark-piller,

Yes, I did that yesterday. I just did it again. I ran npm i and also npm i backendless-coderunner and now it’s version 5.5.0. Seems all packages are up-to-date. Yet the problem remains.

Best
Evan

11

Hi Evan,

The latest version of backendless-coderunner is 6.0.0. You can see it here:

Please make sure your installation is using that version.

Regards,
Mark

12

Hi @mark-piller

Thanks. Simply npm i didn’t install the latest coderunner for me somehow. I specify the version explicitly. And it worked.

Thanks a lot!
Evan