Correct way to use pre('remove')?

[Vinaya Sathyanarayana]

Hello,

I have a need to prevent deletion if a record is locked. Sample code is given below.

I need to 

a. flash a message that Record is Locked and cannot be deleted --> Not working : says req object is undefined

b. prevent deletion --> (i) The record is not getting deleted (good). (ii) Error message is not getting displayed (iii) mongoose error stack is thrown : how to catch and handle the error

Order.schema.pre('remove', function(next) {

    if (this.orderstate == CONST_LOCKED) {

        // record already locked - do not save - provide a message

        debug ('Already Locked');

        //req.flash('error', 'Already Locked Order!');

        var delerr = new Error('Cannot Delete - Locked Order');

        //return (delerr); // Do not delete

        next (delerr);

    }

    else {

        next ();

    }

});